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Old page wikitext, before the edit (old_wikitext) | '{{short description|Method of staining used to differentiate bacterial species into two large groups (Gram-positive and Gram-negative)}}
[[File:Gram stain 01.jpg|thumb|A Gram stain of mixed ''[[Staphylococcus aureus]]'' (''S. aureus'' ATCC 25923, Gram-positive cocci, in purple) and ''[[Escherichia coli]]'' (''E. coli'' ATCC 11775, Gram-negative bacilli, in red), the most common Gram stain reference bacteria]]
'''Gram stain''' or '''Gram staining''', also called '''Gram's method''', is a method of [[staining]] used to distinguish and classify [[bacteria]]l species into two large groups ([[Gram-positive bacteria|Gram-positive]] and [[Gram-negative bacteria|Gram-negative]]). The name comes from the Danish [[bacteriologist]] [[Hans Christian Gram]], who developed the technique.<ref>{{cite journal |last1=Colco |first1=R |title=Gram Staining |journal=Current Protocols in Microbiology |date=2005 |volume=00 |issue=1 |pages=Appendix 3C |doi=10.1002/9780471729259.mca03cs00 |pmid=18770544 |isbn=978-0471729259 }}</ref>
Gram staining differentiates bacteria by the chemical and physical properties of their [[cell wall]]s. Gram-positive cells have a thick layer of [[peptidoglycan]] in the cell wall that retains the primary stain, [[crystal violet]]. Gram-negative cells have a thinner peptidoglycan layer that allows the crystal violet to wash out. They are stained pink by the [[counterstain]],<ref name="Beveridge_and_Davies_1983"/> commonly [[safranin]] or [[fuchsine]].
The Gram stain is almost always the first step in the preliminary identification of a bacterial organism. While Gram staining is a valuable diagnostic tool in both clinical and research settings, not all bacteria can be definitively classified by this technique. This gives rise to ''Gram-variable'' and ''Gram-indeterminate'' groups.
==History==
The method is named after its inventor, the [[Denmark|Danish]] scientist [[Hans Christian Gram]] (1853–1938), who developed the technique while working with [[Carl Friedländer]] in the morgue of the city hospital in [[Berlin]] in 1884. Gram devised his technique not for the purpose of distinguishing one type of bacterium from another but to make bacteria more visible in stained sections of lung tissue.<ref>{{Cite journal|last=Austrian|first=R.|year=1960|title=The Gram stain and the etiology of lobar pneumonia, an historical note|journal=Bacteriological Reviews|volume=24|issue=3|pages=261–265|pmid=13685217|pmc=441053}}</ref> He published his method in 1884, and included in his short report the observation that the [[typhus]] [[bacillus (shape)|bacillus]] did not retain the stain.<ref name=Gram_1884>{{Cite journal |authorlink = Hans Christian Gram |last = Gram |first = H.C. |title = Über die isolierte Färbung der Schizomyceten in Schnitt- und Trockenpräparaten |journal = Fortschritte der Medizin |language=German |year = 1884 |volume = 2 |pages = 185–189}}.<br>English translation in: {{Cite book|last=Brock|first=T.D.|year=1999|title=Milestones in Microbiology 1546–1940|edition=2|publisher=ASM Press|place= |pages=215–218|isbn=978-1-55581-142-6|url=https://books.google.com/?id=q5JHcs8w21gC&lpg=PP1&dq=Milestones%20in%20Microbiology&pg=PA215#v=onepage&q}}<br/>Translation is also at: {{Cite journal|url=http://www.hoslink.com/pathology/lab_general/history2.htm#gram|last=Brock|first=T.D.|title=Pioneers in Medical Laboratory Science: Christian Gram 1884|publisher=Hoslink|accessdate=2010-07-27}}</ref>
==Uses==
Gram staining is a [[bacteriology|bacteriological]] [[laboratory]] technique<ref name=Sherris>{{cite book |author = Ryan K.J., Ray C.G. (editors) |title = Sherris Medical Microbiology |pages = 232f |edition = 4th |publisher = McGraw Hill |year = 2004 |isbn= 978-0838585290 }}{{full citation needed|date=March 2016}}</ref> used to differentiate [[bacterium|bacterial]] species into two large groups ([[Gram-positive]] and [[Gram-negative]]) based on the physical properties of their [[cell wall]]s.<ref name=Madigan_2004>{{cite book |last = Madigan |first = M.T. |author2 = Martinko J. |author3 = Parker J. |title = Brock Biology of Microorganisms |edition = 10th |publisher = Lippincott Williams & Wilkins |year = 2004 |isbn = 978-0-13-066271-2 |url-access = registration |url = https://archive.org/details/brockbiologyofmi00madi }}{{full citation needed|date=March 2016}}</ref>{{page needed|date=March 2016}} Gram staining is not used to classify [[archaea]], formerly archaeabacteria, since these microorganisms yield widely varying responses that do not follow their [[phylogenetics|phylogenetic groups]].<ref>{{cite journal |author=Beveridge T.J. |title=Use of the Gram stain in microbiology |journal=Biotechnic & Histochemistry |volume=76 |issue=3 |pages=111–118 |year=2001 |pmid=11475313 |doi=10.1080/714028139}}</ref>
The Gram stain is not an infallible tool for diagnosis, identification, or phylogeny, and it is of extremely limited use in [[environmental microbiology]]. It is used mainly to make a preliminary morphologic identification or to establish that there are significant numbers of bacteria in a clinical specimen. It cannot identify bacteria to the species level, and for most medical conditions, it should not be used as the sole method of bacterial identification. In clinical microbiology laboratories, it is used in combination with other traditional and molecular techniques to identify bacteria. Some organisms are Gram-variable (meaning they may stain either negative or positive); some are not stained with either dye used in the Gram technique and are not seen. In a modern environmental or molecular microbiology lab, most identification is done using genetic sequences and other molecular techniques, which are far more specific and informative than differential staining.
Gram staining has been suggested to be as effective a diagnostic tool as [[polymerase chain reaction|PCR]] in one primary research report regarding gonococcal urethritis.<ref>El-Garnal, A.H., Al-Otaibi, S.R., Alshamali, A., Abdulrazzaq, A., Najem, N., and Fouzan, A.A. Polymerase chain reaction is no better than Gram stain for diagnosis of gonococcal urethritis. Indian Journal of Dermatology, Venereology and Leprology, (2009); 75, 101.{{primary source inline|date=March 2016}}</ref>{{primary source inline|date=March 2016}}
===Medical===
{{see also|Gram-negative bacterial infection|Gram-positive bacterial infection}}
Gram stains are performed on [[body fluid]] or [[biopsy]] when [[infection]] is suspected. Gram stains yield results much more quickly than [[microbiological culture|culturing]], and is especially important when infection would make an important difference in the patient's treatment and prognosis; examples are [[cerebrospinal fluid]] for [[meningitis]] and [[synovial fluid]] for [[septic arthritis]].<ref name=Sherris /><ref name="Søgaard_2007">{{cite journal |author1=Søgaard M. |author2=Nørgaard M. |author3=Schønheyder H. |title=First notification of positive blood cultures: high accuracy of the Gram stain report |journal=Journal of Clinical Microbiology |volume= 45|issue= 4|pages= 1113–1117|year= 2007 |pmid=17301283 |doi=10.1128/JCM.02523-06 |pmc=1865800}}</ref>
===Staining mechanism===
[[File:Gram Staining Bacteria.jpg|thumb|Purple-stained Gram-positive (left) and pink-stained Gram-negative (right)]]
Gram-positive bacteria have a thick mesh-like cell wall made of [[peptidoglycan]] (50–90% of cell envelope), and as a result are stained purple by crystal violet, whereas Gram-negative bacteria have a thinner layer (10% of cell envelope), so do not retain the purple stain and are counter-stained pink by safranin. There are four basic steps of the Gram stain:
*Applying a primary stain ([[gentian violet|crystal violet]]) to a heat-fixed smear of a bacterial culture. [[Heat fixation]] kills some bacteria but is mostly used to affix the bacteria to the slide so that they don't rinse out during the staining procedure.
*The addition of [[iodide]], which binds to crystal violet and traps it in the cell
*Rapid decolorization with [[ethanol]] or [[acetone]]
*''[[Counterstain]]ing'' with [[safranin]].<ref>Microbiology: Principles and Explorations, p 65; Jacquelyn G. Black, Prentice Hall, 1993.</ref> [[Carbol fuchsin]] is sometimes substituted for safranin since it more intensely stains anaerobic bacteria, but it is less commonly used as a counterstain.<ref>{{cite web|url=http://www.med-chem.com/index.php?url=lab_procedures&subsection=gram_staining|title=Medical Chemical Corporation|date=|work=med-chem.com|accessdate=9 March 2016}}</ref>
{| class="wikitable"
|+Summary of Gram stain
|-
! rowspan=2|Application of || rowspan=2|Reagent || colspan=4|Cell color
|-
! Gram-positive || Gram-negative
|-
| Primary dye || [[crystal violet]] || purple || purple
|-
| Trapping agent || [[iodine]] || purple || purple
|-
| Decolorizer || [[ethanol|alcohol]]/[[acetone]] || purple || colorless
|-
| Counter stain || [[safranin]]/[[carbol fuchsin]] || purple || pink
|}
[[Crystal violet]] (CV) dissociates in aqueous solutions into {{chem|CV|+}} and chloride ({{chem|Cl|-}}) ions. These ions penetrate the cell wall of both Gram-positive and Gram-negative cells. The {{chem|CV|+}} ion interacts with negatively charged components of bacterial cells and stains the cells purple.<ref>{{cite book|last1=Leboffe|first1=Michael|title=Microbiology Laboratory Theory and Application|date=2014|publisher=Morton Publishing Company|location=Englewood, CO|isbn=978-1617312809|pages=105|edition=3rd}}</ref>
Iodide ({{chem|I|-}} or {{chem|I|3|-}}) interacts with {{chem|CV|+}} and forms large complexes of crystal violet and iodine (CV–I) within the inner and outer layers of the cell. Iodine is often referred to as a [[mordant]], but is a trapping agent that prevents the removal of the CV–I complex and, therefore, colors the cell.<ref name="Stainsfile - Trapping Agents">{{cite web|url=http://stainsfile.info/StainsFile/theory/notmrdnt.htm|title=StainsFile - Stain theory - What a mordant is not|date=|work=stainsfile.info|accessdate=9 March 2016}}</ref>
When a decolorizer such as alcohol or acetone is added, it interacts with the lipids of the cell membrane.<ref>{{Cite web|url=http://www.austincc.edu/microbugz/gram_stain.php|title=Welcome to Microbugz - Gram Stain|website=www.austincc.edu|access-date=2017-05-26}}</ref> A Gram-negative cell loses its outer lipopolysaccharide membrane, and the inner peptidoglycan layer is left exposed. The CV–I complexes are washed from the gram-negative cell along with the outer membrane.<ref name=":0">{{Cite book|title=Pharmaceutical microbiology : essentials for quality assurance and quality control|last=Tim |first=Sandle |isbn=9780081000229|oclc=923807961|date = 2015-10-21}}</ref>{{citation needed|date=March 2016}} In contrast, a Gram-positive cell becomes dehydrated from an ethanol treatment. The large CV–I complexes become trapped within the Gram-positive cell due to the multilayered nature of its peptidoglycan.<ref name=":0" />{{citation needed|date=March 2016}} The decolorization step is critical and must be timed correctly; the crystal violet stain is removed from both Gram-positive and negative cells if the decolorizing agent is left on too long (a matter of seconds).<ref name=":1">{{cite web |title=Gram's Serendipitous Stain |publisher=Hardy's Diagnostics |url=http://hardydiagnostics.com/wp-content/uploads/2016/05/Hans-Christian-Gram.pdf |last1=Hardy |first1=Jay |last2=Maria |first2=Santa }}</ref>
After decolorization, the Gram-positive cell remains purple and the Gram-negative cell loses its purple color.<ref name=":1" />{{citation needed|date=March 2016}} Counterstain, which is usually positively charged safranin or basic fuchsine, is applied last to give decolorized Gram-negative bacteria a pink or red color.<ref name="Beveridge_and_Davies_1983">{{cite journal |author1=Beveridge T. J. |author2=Davies J. A. |title=Cellular responses of Bacillus subtilis and Escherichia coli to the Gram stain |journal=Journal of Bacteriology |volume=156 |issue=2 |pages=846–58 |date=November 1983 |pmid=6195148 |pmc=217903 |doi= |url=http://jb.asm.org/cgi/pmidlookup?view=long&pmid=6195148}}</ref><ref name="Davies_et_al_1983">{{cite journal |author1=Davies J. A. |author2=Anderson G. K. |author3=Beveridge T. J. |author4=Clark H. C. |title=Chemical mechanism of the Gram stain and synthesis of a new electron-opaque marker for electron microscopy, which replaces the iodine mordant of the stain |journal=Journal of Bacteriology |volume=156 |issue=2 |pages=837–845 |date=November 1983 |pmid=6195147 |pmc=217902 |doi= |url=http://jb.asm.org/cgi/pmidlookup?view=long&pmid=6195147}}</ref> Both Gram-positive bacteria and Gram-negative bacteria pick up the counterstain. The counterstain, however, is unseen on Gram-positive bacteria because of the darker crystal violet stain.
==Examples==
===Gram-positive bacteria===
{{Main|Gram-positive bacteria}}
Gram-positive bacteria generally have a single membrane (''monoderm'') surrounded by a thick peptidoglycan.
This rule is followed by two phyla: ''[[Firmicutes]]'' (except for the classes [[Mollicutes]] and [[Negativicutes]]) and the ''[[Actinobacteria]]''.<ref name="Madigan_2004" /><ref name="Begey_essay">{{cite book |series=Bergey's Manual of Systematic Bacteriology|volume=2A|title=Introductory Essays|editor=George M. Garrity |authors=Don J. Brenner, Noel R. Krieg, James T. Staley |publisher=Springer|location= New York |edition=2nd|isbn=978-0-387-24143-2 |pages=304 |url=https://www.springer.com/life+sciences/book/978-0-387-24143-2 |date=July 26, 2005 |origyear=1984|id=British Library no. GBA561951}}{{Page needed|date=October 2013}}</ref> In contrast, members of the [[Chloroflexi (phylum)|Chloroflexi]] (green non-sulfur bacteria) are monoderms but possess a thin or absent (class [[Dehalococcoidetes]]) peptidoglycan and can stain negative, positive or indeterminate; members of the [[Deinococcus–Thermus|''Deinococcus–Thermus'' group]] stain positive but are diderms with a thick peptidoglycan.<ref name="Madigan_2004" />{{page needed|date=March 2016}}<ref name="Begey_essay"/>
[[Bacterial taxonomy|Historically]], the Gram-positive forms made up the [[phylum (biology)|phylum]] ''[[Firmicutes]]'', a name now used for the largest group. It includes many well-known genera such as ''[[Bacillus]]'', ''[[Listeria]]'', ''[[Staphylococcus]]'', ''[[Streptococcus]]'', ''[[Enterococcus]]'', and ''[[Clostridium]]''.<ref>{{Cite journal|last=Galperin|first=Michael Y.|date=2013-12-27|title=Genome Diversity of Spore-Forming Firmicutes|journal=Microbiology Spectrum|volume=1|issue=2|doi=10.1128/microbiolspectrum.tbs-0015-2012|issn=2165-0497|pmc=4306282|pmid=26184964}}</ref>{{citation needed|date=March 2016}} It has also been expanded to include the ''Mollicutes'', bacteria like ''[[Mycoplasma]]'' that lack cell walls and so cannot be Gram-stained, but are derived from such forms.<ref>Practical Medical Microbiology by Hams H. Hashem, from http://qu.edu.iq/el/mod/resource/view.php?id=1391</ref>{{citation needed|date=March 2016}}
Some bacteria have cell walls which are particularly adept at retaining stains. These will appear positive by Gram stain even though they are not closely related to other Gram-positive bacteria. These are called [[acid-fastness|acid-fast bacteria]], and can only be differentiated from other Gram-positive bacteria by [[Ziehl–Neelsen stain|special staining procedures]].<ref>{{Cite web|url=http://www2.highlands.edu/academics/divisions/scipe/biology/labs/rome/acid_fast_stain.htm|title=The Acid Fast Stain|website=www2.highlands.edu|access-date=2017-06-09}}</ref>{{citation needed|date=March 2016}}
===Gram-negative bacteria===
{{Main|Gram-negative bacteria}}
<!--Definition of Gr- purposefully repeated-->Gram-negative bacteria generally possess a thin layer of peptidoglycan between two membranes (''diderms''). Most [[bacterial phyla]] are Gram-negative, including the [[cyanobacteria]], [[green sulfur bacteria]], and most ''[[Proteobacteria]]'' (exceptions being some members of the ''[[Rickettsiales]]'' and the insect-endosymbionts of the ''[[Enterobacteriales]]'').<ref name="Madigan_2004" />{{page needed|date=March 2016}}<ref name="Begey_essay" />
===Gram-variable and Gram-indeterminate bacteria===
Some bacteria, after staining with the Gram stain, yield a Gram-variable pattern: a mix of pink and purple cells are seen.<ref name=":0" />{{citation needed|date=October 2015}} In cultures of Bacillus, Butyrivibrio, and Clostridium, a decrease in peptidoglycan thickness during growth coincides with an increase in the number of cells that stain Gram-negative.<ref name="Beveridge_1990">{{cite journal |last=Beveridge|first=Terry J.|title=Mechanism of gram variability in select bacteria |journal=Journal of Bacteriology |volume=172 |issue=3 |pages=1609–20 |date=March 1990 |pmid=1689718 |pmc=208639 |doi= 10.1128/jb.172.3.1609-1620.1990}}</ref> In addition, in all bacteria stained using the Gram stain, the age of the culture may influence the results of the stain.<ref name="Beveridge_1990"/>
Gram-indeterminate bacteria do not respond predictably to Gram staining and, therefore, cannot be determined as either Gram-positive or Gram-negative. Examples include many species of ''[[Mycobacterium]]'', including ''[[Mycobacterium tuberculosis|M. tuberculosis]]'' and ''[[Mycobacterium leprae|M. leprae]]''.<ref>{{cite book|last=Black|first=Jacquelyn|title=Microbiology: Principles and Exploration|edition=8th|date=2012|publisher=John Wiley & Sons|isbn=978-0-470-54109-8|page=68}}</ref><ref name="pmid19885935">{{cite journal |author1=Reynolds J. |author2=Moyes R.B. |author3=Breakwell D.P. |title=Differential staining of bacteria: acid fast stain|journal=[[Current Protocols#Titles|Current Protocols in Microbiology]]|year=2009|pages=Appendix 3H | doi=10.1002/9780471729259.mca03hs15|pmid=19885935|volume=Appendix 3|isbn=978-0471729259 }}</ref>
== Orthographic note ==
The term "Gram staining" is derived from the surname of [[Hans Christian Gram]]; the [[eponym]] (Gram) is therefore capitalized but not the common noun (stain) as is usual for scientific terms.<ref>{{cite book |url=https://books.google.com/books?id=btb1AwAAQBAJ&pg=PA105 |title=New Hart's Rules: The Oxford Style Guide|first= Anne |last=Waddingham |page=105 |publisher=OUP Oxford |date=28 August 2014 |isbn= 978-0199570027 }}</ref> The initial letters of "Gram-positive" and "Gram-negative", which are [[eponym#Orthographic conventions|eponymous adjectives]], can be either lowercase "g" or capital "G", depending on what [[style guide]] (if any) governs the document being written. Lowercase style is used by the US [[Centers for Disease Control and Prevention]] and other style regimens such as the [[AMA style]].<ref>Centers for Disease Control and Prevention. Emerging Infectious Diseases Journal Style Guide. [http://wwwnc.cdc.gov/eid/pages/preferred-usage.htm Preferred Usage]</ref> Dictionaries may use lowercase,<ref name="Dorlands">{{Citation |author=Elsevier |authorlink=Elsevier |title=Dorland's Illustrated Medical Dictionary |publisher=Elsevier |url=http://www.dorlands.com/ |postscript=.}}</ref><ref name="MWMD">{{Citation |author=Merriam-Webster |authorlink=Merriam-Webster |title=gram–positive |publisher=Merriam-Webster |url=http://www.merriam-webster.com/dictionary/gram%E2%80%93positive |postscript=.}}</ref> uppercase,<ref>{{cite web |url=http://www.collinsdictionary.com/dictionary/english/gram-positive |title=Definition of Gram-positive |work=Collins}}</ref><ref>{{cite web |url= https://en.oxforddictionaries.com/definition/gram_stain |title=Gram stain |work=Oxford Dictionary}}</ref><ref>{{cite web |url=http://www.medicinenet.com/script/main/art.asp?articlekey=9585 |title=Definition of Gram-positive |work=Medicinenet}}</ref><ref>{{cite web |url=http://www.businessdictionary.com/definition/Gram-negative-positive.html |title=Gram negative/positive |work= Business dictionary}}</ref> or both.<ref>{{cite web |url=https://ahdictionary.com/word/search.html?q=gram+positive&submit.x=0&submit.y=0 |title=gram-pos·i·tive or Gram-pos·i·tive |work=The American Heritage Dictionary }}</ref><ref name="dictionary">{{cite web|url=http://www.dictionary.com/browse/gram-positive |title=Gram-positive |work=Dictionary.com}}</ref> Uppercase 'Gram-positive' or 'Gram-negative' usage is also common in many [[scientific journal]] articles and publications.<ref name="dictionary"/><ref>{{cite journal |title=Through the wall: extracellular vesicles in Gram-positive bacteria, mycobacteria and fungi |authors=Lisa Brown, Julie M. Wolf, Rafael Prados-Rosales & Arturo Casadevall|journal=Nature Reviews Microbiology |volume=13 |issue=10 |pages= 620–630 |date=2015 |doi= 10.1038/nrmicro3480 |pmid=26324094 |pmc=4860279}}</ref><ref>{{cite journal |journal=Science |title=Detecting Gram-negative bacteria |date=12 June 2015 |volume=348|issue= 6240|page= 1218|doi= 10.1126/science.348.6240.1218-o |author= Kristen L. Mueller}}</ref> When articles are submitted to journals, each journal may or may not apply house style to the [[postprint]] version. [[Preprint]] versions contain whichever style the author happened to use. Even style regimens that use lowercase for the adjectives "gram-positive" and "gram-negative" still use capital for "Gram stain".
==See also==
*[[Bacterial cell structure]]
*[[Ziehl–Neelsen stain ]]
==References==
{{Reflist}}
==External links==
{{Commons category|Gram stains}}
{{Wikibooks|School Science|Gram staining}}
*[http://www.tgw1916.net/movies.html Gram staining technique video]
{{Stains}}
[[Category:Articles with inconsistent citation formats]]
[[Category:Bacteriology]]
[[Category:Staining]]
[[Category:Microscopy]]
[[Category:Danish inventions]]
[[Category:1884 in biology]]' |
New page wikitext, after the edit (new_wikitext) | '{{short description|Method of staining used to differentiate bacterial species into two large groups (Gram-positive and Gram-negative)}}
[[File:Gram stain 01.jpg|thumb|A Gram stain of mixed ''[[Staphylococcus aureus]]'' (''S. aureus'' ATCC 25923, Gram-positive cocci, in purple) and ''[[Escherichia coli]]'' (''E. coli'' ATCC 11775, Gram-negative bacilli, in red), the most common Gram stain reference bacteria]]
'''Gram stain''' or '''Gram staining''', also called '''Gram's method''', is a method of [[staining]] used to distinguish and classify [[bacteria]]l species into two large groups ([[Gram-positive bacteria|Gram-positive]] and [[Gram-negative bacteria|Gram-negative]]). The name comes from the Danish [[bacteriologist]] [[Hans Christian Gram]], who developed the technique.<ref>{{cite journal |last1=Colco |first1=R |title=Gram Staining |journal=Current Protocols in Microbiology |date=2005 |volume=00 |issue=1 |pages=Appendix 3C |doi=10.1002/9780471729259.mca03cs00 |pmid=18770544 |isbn=978-0471729259 }}</ref>
Gram staining differentiates bacteria by the chemical and physical properties of their [[cell wall]]s. Gram-positive cells have a thick layer of [[peptidoglycan]] in the cell wall that retains the primary stain, [[crystal violet]]. Gram-negative cells have a thinner peptidoglycan layer that allows the crystal violet to wash out. They are stained pink by the [[counterstain]],<ref name="Beveridge_and_Davies_1983"/> commonly [[safranin]] or [[fuchsine]].
The Gram stain is almost always the first step in the preliminary identification of a bacterial organism. While Gram staining is a valuable diagnostic tool in both clinical and research settings, not all bacteria can be definitively classified by this technique. This gives rise to ''Gram-variable'' and ''Gram-indeterminate'' groups.
==History==
The method is named after its inventor, the [[Denmark|Danish]] scientist [[Hans Christian Gram]] (1853–1938), who developed the technique while working with [[Carl Friedländer]] in the morgue of the city hospital in [[Berlin]] in 1884. Gram devised his technique not for the purpose of distinguishing one type of bacterium from another but to make bacteria more visible in stained sections of lung tissue.<ref>{{Cite journal|last=Austrian|first=R.|year=1960|title=The Gram stain and the etiology of lobar pneumonia, an historical note|journal=Bacteriological Reviews|volume=24|issue=3|pages=261–265|pmid=13685217|pmc=441053}}</ref> He published his method in 1884, and included in his short report the observation that the [[typhus]] [[bacillus (shape)|bacillus]] did not retain the stain.<ref name=Gram_1884>{{Cite journal |authorlink = Hans Christian Gram |last = Gram |first = H.C. |title = Über die isolierte Färbung der Schizomyceten in Schnitt- und Trockenpräparaten |journal = Fortschritte der Medizin |language=German |year = 1884 |volume = 2 |pages = 185–189}}.<br>English translation in: {{Cite book|last=Brock|first=T.D.|year=1999|title=Milestones in Microbiology 1546–1940|edition=2|publisher=ASM Press|place= |pages=215–218|isbn=978-1-55581-142-6|url=https://books.google.com/?id=q5JHcs8w21gC&lpg=PP1&dq=Milestones%20in%20Microbiology&pg=PA215#v=onepage&q}}<br/>Translation is also at: {{Cite journal|url=http://www.hoslink.com/pathology/lab_general/history2.htm#gram|last=Brock|first=T.D.|title=Pioneers in Medical Laboratory Science: Christian Gram 1884|publisher=Hoslink|accessdate=2010-07-27}}</ref>
==Uses==
Gram staining is a [[bacteriology|bacteriological]] [[laboratory]] technique<ref name=Sherris>{{cite book |author = Ryan K.J., Ray C.G. (editors) |title = Sherris Medical Microbiology |pages = 232f |edition = 4th |publisher = McGraw Hill |year = 2004 |isbn= 978-0838585290 }}{{full citation needed|date=March 2016}}</ref> used to differentiate [[bacterium|bacterial]] species into two large groups ([[Gram-positive]] and [[Gram-negative]]) based on the physical properties of their [[cell wall]]s.<ref name=Madigan_2004>{{cite book |last = Madigan |first = M.T. |author2 = Martinko J. |author3 = Parker J. |title = Brock Biology of Microorganisms |edition = 10th |publisher = Lippincott Williams & Wilkins |year = 2004 |isbn = 978-0-13-066271-2 |url-access = registration |url = https://archive.org/details/brockbiologyofmi00madi }}{{full citation needed|date=March 2016}}</ref>{{page needed|date=March 2016}} Gram staining is not used to classify [[archaea]], formerly archaeabacteria, since these microorganisms yield widely varying responses that do not follow their [[phylogenetics|phylogenetic groups]].<ref>{{cite journal |author=Beveridge T.J. |title=Use of the Gram stain in microbiology |journal=Biotechnic & Histochemistry |volume=76 |issue=3 |pages=111–118 |year=2001 |pmid=11475313 |doi=10.1080/714028139}}</ref>
The Gram stain is not an infallible tool for diagnosis, identification, or phylogeny, and it is of extremely limited use in [[environmental microbiology]]. It is used mainly to make a preliminary morphologic identification or to establish that there are significant numbers of bacteria in a clinical specimen. It cannot identify bacteria to the species level, and for most medical conditions, it should not be used as the sole method of bacterial identification. In clinical microbiology laboratories, it is used in combination with other traditional and molecular techniques to identify bacteria. Some organisms are Gram-variable (meaning they may stain either negative or positive); some are not stained with either dye used in the Gram technique and are not seen. In a modern environmental or molecular microbiology lab, most identification is done using genetic sequences and other molecular techniques, which are far more specific and informative than differential staining.
Gram staining has been suggested to be as effective a diagnostic tool as [[polymerase chain reaction|PCR]] in one primary research report regarding gonococcal urethritis.<ref>El-Garnal, A.H., Al-Otaibi, S.R., Alshamali, A., Abdulrazzaq, A., Najem, N., and Fouzan, A.A. Polymerase chain reaction is no better than Gram stain for diagnosis of gonococcal urethritis. Indian Journal of Dermatology, Venereology and Leprology, (2009); 75, 101.{{primary source inline|date=March 2016}}</ref>{{primary source inline|date=March 2016}}
===Medical===
{{see also|Gram-negative bacterial infection|Gram-positive bacterial infection}}
Gram stains are performed on [[body fluid]] or [[biopsy]] when [[infection]] is suspected. Gram stains yield results much more quickly than [[microbiological culture|culturing]], and is especially important when infection would make an important difference in the patient's treatment and prognosis; examples are [[cerebrospinal fluid]] for [[meningitis]] and [[synovial fluid]] for [[septic arthritis]].<ref name=Sherris /><ref name="Søgaard_2007">{{cite journal |author1=Søgaard M. |author2=Nørgaard M. |author3=Schønheyder H. |title=First notification of positive blood cultures: high accuracy of the Gram stain report |journal=Journal of Clinical Microbiology |volume= 45|issue= 4|pages= 1113–1117|year= 2007 |pmid=17301283 |doi=10.1128/JCM.02523-06 |pmc=1865800}}</ref>
B. cereus is a common soil saprophyte and is easily spread to many types of foods, especially of plant origin, but is also frequently isolated from meat, eggs and dairy products. The development of psychrotrophic strains in the dairy industry has led to increasing surveillance of B. cereus in recent years. B. cereus food poisoning is underreported as both types of illness are relatively mild and usually last for less than 24 h. However, occasional reports have described a more severe form of the diarrhoeal type of B. cereus food poisoning.
<ref></ref>
==Examples==
===Gram-positive bacteria===
{{Main|Gram-positive bacteria}}
Gram-positive bacteria generally have a single membrane (''monoderm'') surrounded by a thick peptidoglycan.
This rule is followed by two phyla: ''[[Firmicutes]]'' (except for the classes [[Mollicutes]] and [[Negativicutes]]) and the ''[[Actinobacteria]]''.<ref name="Madigan_2004" /><ref name="Begey_essay">{{cite book |series=Bergey's Manual of Systematic Bacteriology|volume=2A|title=Introductory Essays|editor=George M. Garrity |authors=Don J. Brenner, Noel R. Krieg, James T. Staley |publisher=Springer|location= New York |edition=2nd|isbn=978-0-387-24143-2 |pages=304 |url=https://www.springer.com/life+sciences/book/978-0-387-24143-2 |date=July 26, 2005 |origyear=1984|id=British Library no. GBA561951}}{{Page needed|date=October 2013}}</ref> In contrast, members of the [[Chloroflexi (phylum)|Chloroflexi]] (green non-sulfur bacteria) are monoderms but possess a thin or absent (class [[Dehalococcoidetes]]) peptidoglycan and can stain negative, positive or indeterminate; members of the [[Deinococcus–Thermus|''Deinococcus–Thermus'' group]] stain positive but are diderms with a thick peptidoglycan.<ref name="Madigan_2004" />{{page needed|date=March 2016}}<ref name="Begey_essay"/>
[[Bacterial taxonomy|Historically]], the Gram-positive forms made up the [[phylum (biology)|phylum]] ''[[Firmicutes]]'', a name now used for the largest group. It includes many well-known genera such as ''[[Bacillus]]'', ''[[Listeria]]'', ''[[Staphylococcus]]'', ''[[Streptococcus]]'', ''[[Enterococcus]]'', and ''[[Clostridium]]''.<ref>{{Cite journal|last=Galperin|first=Michael Y.|date=2013-12-27|title=Genome Diversity of Spore-Forming Firmicutes|journal=Microbiology Spectrum|volume=1|issue=2|doi=10.1128/microbiolspectrum.tbs-0015-2012|issn=2165-0497|pmc=4306282|pmid=26184964}}</ref>{{citation needed|date=March 2016}} It has also been expanded to include the ''Mollicutes'', bacteria like ''[[Mycoplasma]]'' that lack cell walls and so cannot be Gram-stained, but are derived from such forms.<ref>Practical Medical Microbiology by Hams H. Hashem, from http://qu.edu.iq/el/mod/resource/view.php?id=1391</ref>{{citation needed|date=March 2016}}
Some bacteria have cell walls which are particularly adept at retaining stains. These will appear positive by Gram stain even though they are not closely related to other Gram-positive bacteria. These are called [[acid-fastness|acid-fast bacteria]], and can only be differentiated from other Gram-positive bacteria by [[Ziehl–Neelsen stain|special staining procedures]].<ref>{{Cite web|url=http://www2.highlands.edu/academics/divisions/scipe/biology/labs/rome/acid_fast_stain.htm|title=The Acid Fast Stain|website=www2.highlands.edu|access-date=2017-06-09}}</ref>{{citation needed|date=March 2016}}
===Gram-negative bacteria===
{{Main|Gram-negative bacteria}}
<!--Definition of Gr- purposefully repeated-->Gram-negative bacteria generally possess a thin layer of peptidoglycan between two membranes (''diderms''). Most [[bacterial phyla]] are Gram-negative, including the [[cyanobacteria]], [[green sulfur bacteria]], and most ''[[Proteobacteria]]'' (exceptions being some members of the ''[[Rickettsiales]]'' and the insect-endosymbionts of the ''[[Enterobacteriales]]'').<ref name="Madigan_2004" />{{page needed|date=March 2016}}<ref name="Begey_essay" />
===Gram-variable and Gram-indeterminate bacteria===
Some bacteria, after staining with the Gram stain, yield a Gram-variable pattern: a mix of pink and purple cells are seen.<ref name=":0" />{{citation needed|date=October 2015}} In cultures of Bacillus, Butyrivibrio, and Clostridium, a decrease in peptidoglycan thickness during growth coincides with an increase in the number of cells that stain Gram-negative.<ref name="Beveridge_1990">{{cite journal |last=Beveridge|first=Terry J.|title=Mechanism of gram variability in select bacteria |journal=Journal of Bacteriology |volume=172 |issue=3 |pages=1609–20 |date=March 1990 |pmid=1689718 |pmc=208639 |doi= 10.1128/jb.172.3.1609-1620.1990}}</ref> In addition, in all bacteria stained using the Gram stain, the age of the culture may influence the results of the stain.<ref name="Beveridge_1990"/>
Gram-indeterminate bacteria do not respond predictably to Gram staining and, therefore, cannot be determined as either Gram-positive or Gram-negative. Examples include many species of ''[[Mycobacterium]]'', including ''[[Mycobacterium tuberculosis|M. tuberculosis]]'' and ''[[Mycobacterium leprae|M. leprae]]''.<ref>{{cite book|last=Black|first=Jacquelyn|title=Microbiology: Principles and Exploration|edition=8th|date=2012|publisher=John Wiley & Sons|isbn=978-0-470-54109-8|page=68}}</ref><ref name="pmid19885935">{{cite journal |author1=Reynolds J. |author2=Moyes R.B. |author3=Breakwell D.P. |title=Differential staining of bacteria: acid fast stain|journal=[[Current Protocols#Titles|Current Protocols in Microbiology]]|year=2009|pages=Appendix 3H | doi=10.1002/9780471729259.mca03hs15|pmid=19885935|volume=Appendix 3|isbn=978-0471729259 }}</ref>
== Orthographic note ==
The term "Gram staining" is derived from the surname of [[Hans Christian Gram]]; the [[eponym]] (Gram) is therefore capitalized but not the common noun (stain) as is usual for scientific terms.<ref>{{cite book |url=https://books.google.com/books?id=btb1AwAAQBAJ&pg=PA105 |title=New Hart's Rules: The Oxford Style Guide|first= Anne |last=Waddingham |page=105 |publisher=OUP Oxford |date=28 August 2014 |isbn= 978-0199570027 }}</ref> The initial letters of "Gram-positive" and "Gram-negative", which are [[eponym#Orthographic conventions|eponymous adjectives]], can be either lowercase "g" or capital "G", depending on what [[style guide]] (if any) governs the document being written. Lowercase style is used by the US [[Centers for Disease Control and Prevention]] and other style regimens such as the [[AMA style]].<ref>Centers for Disease Control and Prevention. Emerging Infectious Diseases Journal Style Guide. [http://wwwnc.cdc.gov/eid/pages/preferred-usage.htm Preferred Usage]</ref> Dictionaries may use lowercase,<ref name="Dorlands">{{Citation |author=Elsevier |authorlink=Elsevier |title=Dorland's Illustrated Medical Dictionary |publisher=Elsevier |url=http://www.dorlands.com/ |postscript=.}}</ref><ref name="MWMD">{{Citation |author=Merriam-Webster |authorlink=Merriam-Webster |title=gram–positive |publisher=Merriam-Webster |url=http://www.merriam-webster.com/dictionary/gram%E2%80%93positive |postscript=.}}</ref> uppercase,<ref>{{cite web |url=http://www.collinsdictionary.com/dictionary/english/gram-positive |title=Definition of Gram-positive |work=Collins}}</ref><ref>{{cite web |url= https://en.oxforddictionaries.com/definition/gram_stain |title=Gram stain |work=Oxford Dictionary}}</ref><ref>{{cite web |url=http://www.medicinenet.com/script/main/art.asp?articlekey=9585 |title=Definition of Gram-positive |work=Medicinenet}}</ref><ref>{{cite web |url=http://www.businessdictionary.com/definition/Gram-negative-positive.html |title=Gram negative/positive |work= Business dictionary}}</ref> or both.<ref>{{cite web |url=https://ahdictionary.com/word/search.html?q=gram+positive&submit.x=0&submit.y=0 |title=gram-pos·i·tive or Gram-pos·i·tive |work=The American Heritage Dictionary }}</ref><ref name="dictionary">{{cite web|url=http://www.dictionary.com/browse/gram-positive |title=Gram-positive |work=Dictionary.com}}</ref> Uppercase 'Gram-positive' or 'Gram-negative' usage is also common in many [[scientific journal]] articles and publications.<ref name="dictionary"/><ref>{{cite journal |title=Through the wall: extracellular vesicles in Gram-positive bacteria, mycobacteria and fungi |authors=Lisa Brown, Julie M. Wolf, Rafael Prados-Rosales & Arturo Casadevall|journal=Nature Reviews Microbiology |volume=13 |issue=10 |pages= 620–630 |date=2015 |doi= 10.1038/nrmicro3480 |pmid=26324094 |pmc=4860279}}</ref><ref>{{cite journal |journal=Science |title=Detecting Gram-negative bacteria |date=12 June 2015 |volume=348|issue= 6240|page= 1218|doi= 10.1126/science.348.6240.1218-o |author= Kristen L. Mueller}}</ref> When articles are submitted to journals, each journal may or may not apply house style to the [[postprint]] version. [[Preprint]] versions contain whichever style the author happened to use. Even style regimens that use lowercase for the adjectives "gram-positive" and "gram-negative" still use capital for "Gram stain".
==See also==
*[[Bacterial cell structure]]
*[[Ziehl–Neelsen stain ]]
==References==
{{Reflist}}
==External links==
{{Commons category|Gram stains}}
{{Wikibooks|School Science|Gram staining}}
*[http://www.tgw1916.net/movies.html Gram staining technique video]
{{Stains}}
[[Category:Articles with inconsistent citation formats]]
[[Category:Bacteriology]]
[[Category:Staining]]
[[Category:Microscopy]]
[[Category:Danish inventions]]
[[Category:1884 in biology]]' |
Unified diff of changes made by edit (edit_diff) | '@@ -21,35 +21,7 @@
Gram stains are performed on [[body fluid]] or [[biopsy]] when [[infection]] is suspected. Gram stains yield results much more quickly than [[microbiological culture|culturing]], and is especially important when infection would make an important difference in the patient's treatment and prognosis; examples are [[cerebrospinal fluid]] for [[meningitis]] and [[synovial fluid]] for [[septic arthritis]].<ref name=Sherris /><ref name="Søgaard_2007">{{cite journal |author1=Søgaard M. |author2=Nørgaard M. |author3=Schønheyder H. |title=First notification of positive blood cultures: high accuracy of the Gram stain report |journal=Journal of Clinical Microbiology |volume= 45|issue= 4|pages= 1113–1117|year= 2007 |pmid=17301283 |doi=10.1128/JCM.02523-06 |pmc=1865800}}</ref>
-===Staining mechanism===
-[[File:Gram Staining Bacteria.jpg|thumb|Purple-stained Gram-positive (left) and pink-stained Gram-negative (right)]]
-Gram-positive bacteria have a thick mesh-like cell wall made of [[peptidoglycan]] (50–90% of cell envelope), and as a result are stained purple by crystal violet, whereas Gram-negative bacteria have a thinner layer (10% of cell envelope), so do not retain the purple stain and are counter-stained pink by safranin. There are four basic steps of the Gram stain:
-*Applying a primary stain ([[gentian violet|crystal violet]]) to a heat-fixed smear of a bacterial culture. [[Heat fixation]] kills some bacteria but is mostly used to affix the bacteria to the slide so that they don't rinse out during the staining procedure.
-*The addition of [[iodide]], which binds to crystal violet and traps it in the cell
-*Rapid decolorization with [[ethanol]] or [[acetone]]
-*''[[Counterstain]]ing'' with [[safranin]].<ref>Microbiology: Principles and Explorations, p 65; Jacquelyn G. Black, Prentice Hall, 1993.</ref> [[Carbol fuchsin]] is sometimes substituted for safranin since it more intensely stains anaerobic bacteria, but it is less commonly used as a counterstain.<ref>{{cite web|url=http://www.med-chem.com/index.php?url=lab_procedures&subsection=gram_staining|title=Medical Chemical Corporation|date=|work=med-chem.com|accessdate=9 March 2016}}</ref>
-{| class="wikitable"
-|+Summary of Gram stain
-|-
-! rowspan=2|Application of || rowspan=2|Reagent || colspan=4|Cell color
-|-
-! Gram-positive || Gram-negative
-|-
-| Primary dye || [[crystal violet]] || purple || purple
-|-
-| Trapping agent || [[iodine]] || purple || purple
-|-
-| Decolorizer || [[ethanol|alcohol]]/[[acetone]] || purple || colorless
-|-
-| Counter stain || [[safranin]]/[[carbol fuchsin]] || purple || pink
-|}
-
-[[Crystal violet]] (CV) dissociates in aqueous solutions into {{chem|CV|+}} and chloride ({{chem|Cl|-}}) ions. These ions penetrate the cell wall of both Gram-positive and Gram-negative cells. The {{chem|CV|+}} ion interacts with negatively charged components of bacterial cells and stains the cells purple.<ref>{{cite book|last1=Leboffe|first1=Michael|title=Microbiology Laboratory Theory and Application|date=2014|publisher=Morton Publishing Company|location=Englewood, CO|isbn=978-1617312809|pages=105|edition=3rd}}</ref>
-
-Iodide ({{chem|I|-}} or {{chem|I|3|-}}) interacts with {{chem|CV|+}} and forms large complexes of crystal violet and iodine (CV–I) within the inner and outer layers of the cell. Iodine is often referred to as a [[mordant]], but is a trapping agent that prevents the removal of the CV–I complex and, therefore, colors the cell.<ref name="Stainsfile - Trapping Agents">{{cite web|url=http://stainsfile.info/StainsFile/theory/notmrdnt.htm|title=StainsFile - Stain theory - What a mordant is not|date=|work=stainsfile.info|accessdate=9 March 2016}}</ref>
-
-When a decolorizer such as alcohol or acetone is added, it interacts with the lipids of the cell membrane.<ref>{{Cite web|url=http://www.austincc.edu/microbugz/gram_stain.php|title=Welcome to Microbugz - Gram Stain|website=www.austincc.edu|access-date=2017-05-26}}</ref> A Gram-negative cell loses its outer lipopolysaccharide membrane, and the inner peptidoglycan layer is left exposed. The CV–I complexes are washed from the gram-negative cell along with the outer membrane.<ref name=":0">{{Cite book|title=Pharmaceutical microbiology : essentials for quality assurance and quality control|last=Tim |first=Sandle |isbn=9780081000229|oclc=923807961|date = 2015-10-21}}</ref>{{citation needed|date=March 2016}} In contrast, a Gram-positive cell becomes dehydrated from an ethanol treatment. The large CV–I complexes become trapped within the Gram-positive cell due to the multilayered nature of its peptidoglycan.<ref name=":0" />{{citation needed|date=March 2016}} The decolorization step is critical and must be timed correctly; the crystal violet stain is removed from both Gram-positive and negative cells if the decolorizing agent is left on too long (a matter of seconds).<ref name=":1">{{cite web |title=Gram's Serendipitous Stain |publisher=Hardy's Diagnostics |url=http://hardydiagnostics.com/wp-content/uploads/2016/05/Hans-Christian-Gram.pdf |last1=Hardy |first1=Jay |last2=Maria |first2=Santa }}</ref>
-
-After decolorization, the Gram-positive cell remains purple and the Gram-negative cell loses its purple color.<ref name=":1" />{{citation needed|date=March 2016}} Counterstain, which is usually positively charged safranin or basic fuchsine, is applied last to give decolorized Gram-negative bacteria a pink or red color.<ref name="Beveridge_and_Davies_1983">{{cite journal |author1=Beveridge T. J. |author2=Davies J. A. |title=Cellular responses of Bacillus subtilis and Escherichia coli to the Gram stain |journal=Journal of Bacteriology |volume=156 |issue=2 |pages=846–58 |date=November 1983 |pmid=6195148 |pmc=217903 |doi= |url=http://jb.asm.org/cgi/pmidlookup?view=long&pmid=6195148}}</ref><ref name="Davies_et_al_1983">{{cite journal |author1=Davies J. A. |author2=Anderson G. K. |author3=Beveridge T. J. |author4=Clark H. C. |title=Chemical mechanism of the Gram stain and synthesis of a new electron-opaque marker for electron microscopy, which replaces the iodine mordant of the stain |journal=Journal of Bacteriology |volume=156 |issue=2 |pages=837–845 |date=November 1983 |pmid=6195147 |pmc=217902 |doi= |url=http://jb.asm.org/cgi/pmidlookup?view=long&pmid=6195147}}</ref> Both Gram-positive bacteria and Gram-negative bacteria pick up the counterstain. The counterstain, however, is unseen on Gram-positive bacteria because of the darker crystal violet stain.
+ B. cereus is a common soil saprophyte and is easily spread to many types of foods, especially of plant origin, but is also frequently isolated from meat, eggs and dairy products. The development of psychrotrophic strains in the dairy industry has led to increasing surveillance of B. cereus in recent years. B. cereus food poisoning is underreported as both types of illness are relatively mild and usually last for less than 24 h. However, occasional reports have described a more severe form of the diarrhoeal type of B. cereus food poisoning.
+<ref></ref>
==Examples==
' |
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0 => ' B. cereus is a common soil saprophyte and is easily spread to many types of foods, especially of plant origin, but is also frequently isolated from meat, eggs and dairy products. The development of psychrotrophic strains in the dairy industry has led to increasing surveillance of B. cereus in recent years. B. cereus food poisoning is underreported as both types of illness are relatively mild and usually last for less than 24 h. However, occasional reports have described a more severe form of the diarrhoeal type of B. cereus food poisoning.',
1 => '<ref></ref>'
] |
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0 => '===Staining mechanism===',
1 => '[[File:Gram Staining Bacteria.jpg|thumb|Purple-stained Gram-positive (left) and pink-stained Gram-negative (right)]]',
2 => 'Gram-positive bacteria have a thick mesh-like cell wall made of [[peptidoglycan]] (50–90% of cell envelope), and as a result are stained purple by crystal violet, whereas Gram-negative bacteria have a thinner layer (10% of cell envelope), so do not retain the purple stain and are counter-stained pink by safranin. There are four basic steps of the Gram stain:',
3 => '*Applying a primary stain ([[gentian violet|crystal violet]]) to a heat-fixed smear of a bacterial culture. [[Heat fixation]] kills some bacteria but is mostly used to affix the bacteria to the slide so that they don't rinse out during the staining procedure.',
4 => '*The addition of [[iodide]], which binds to crystal violet and traps it in the cell',
5 => '*Rapid decolorization with [[ethanol]] or [[acetone]]',
6 => '*''[[Counterstain]]ing'' with [[safranin]].<ref>Microbiology: Principles and Explorations, p 65; Jacquelyn G. Black, Prentice Hall, 1993.</ref> [[Carbol fuchsin]] is sometimes substituted for safranin since it more intensely stains anaerobic bacteria, but it is less commonly used as a counterstain.<ref>{{cite web|url=http://www.med-chem.com/index.php?url=lab_procedures&subsection=gram_staining|title=Medical Chemical Corporation|date=|work=med-chem.com|accessdate=9 March 2016}}</ref>',
7 => '{| class="wikitable"',
8 => '|+Summary of Gram stain',
9 => '|-',
10 => '! rowspan=2|Application of || rowspan=2|Reagent || colspan=4|Cell color',
11 => '|-',
12 => '! Gram-positive || Gram-negative ',
13 => '|-',
14 => '| Primary dye || [[crystal violet]] || purple || purple ',
15 => '|-',
16 => '| Trapping agent || [[iodine]] || purple || purple ',
17 => '|-',
18 => '| Decolorizer || [[ethanol|alcohol]]/[[acetone]] || purple || colorless ',
19 => '|-',
20 => '| Counter stain || [[safranin]]/[[carbol fuchsin]] || purple || pink ',
21 => '|}',
22 => '',
23 => '[[Crystal violet]] (CV) dissociates in aqueous solutions into {{chem|CV|+}} and chloride ({{chem|Cl|-}}) ions. These ions penetrate the cell wall of both Gram-positive and Gram-negative cells. The {{chem|CV|+}} ion interacts with negatively charged components of bacterial cells and stains the cells purple.<ref>{{cite book|last1=Leboffe|first1=Michael|title=Microbiology Laboratory Theory and Application|date=2014|publisher=Morton Publishing Company|location=Englewood, CO|isbn=978-1617312809|pages=105|edition=3rd}}</ref>',
24 => '',
25 => 'Iodide ({{chem|I|-}} or {{chem|I|3|-}}) interacts with {{chem|CV|+}} and forms large complexes of crystal violet and iodine (CV–I) within the inner and outer layers of the cell. Iodine is often referred to as a [[mordant]], but is a trapping agent that prevents the removal of the CV–I complex and, therefore, colors the cell.<ref name="Stainsfile - Trapping Agents">{{cite web|url=http://stainsfile.info/StainsFile/theory/notmrdnt.htm|title=StainsFile - Stain theory - What a mordant is not|date=|work=stainsfile.info|accessdate=9 March 2016}}</ref>',
26 => '',
27 => 'When a decolorizer such as alcohol or acetone is added, it interacts with the lipids of the cell membrane.<ref>{{Cite web|url=http://www.austincc.edu/microbugz/gram_stain.php|title=Welcome to Microbugz - Gram Stain|website=www.austincc.edu|access-date=2017-05-26}}</ref> A Gram-negative cell loses its outer lipopolysaccharide membrane, and the inner peptidoglycan layer is left exposed. The CV–I complexes are washed from the gram-negative cell along with the outer membrane.<ref name=":0">{{Cite book|title=Pharmaceutical microbiology : essentials for quality assurance and quality control|last=Tim |first=Sandle |isbn=9780081000229|oclc=923807961|date = 2015-10-21}}</ref>{{citation needed|date=March 2016}} In contrast, a Gram-positive cell becomes dehydrated from an ethanol treatment. The large CV–I complexes become trapped within the Gram-positive cell due to the multilayered nature of its peptidoglycan.<ref name=":0" />{{citation needed|date=March 2016}} The decolorization step is critical and must be timed correctly; the crystal violet stain is removed from both Gram-positive and negative cells if the decolorizing agent is left on too long (a matter of seconds).<ref name=":1">{{cite web |title=Gram's Serendipitous Stain |publisher=Hardy's Diagnostics |url=http://hardydiagnostics.com/wp-content/uploads/2016/05/Hans-Christian-Gram.pdf |last1=Hardy |first1=Jay |last2=Maria |first2=Santa }}</ref>',
28 => '',
29 => 'After decolorization, the Gram-positive cell remains purple and the Gram-negative cell loses its purple color.<ref name=":1" />{{citation needed|date=March 2016}} Counterstain, which is usually positively charged safranin or basic fuchsine, is applied last to give decolorized Gram-negative bacteria a pink or red color.<ref name="Beveridge_and_Davies_1983">{{cite journal |author1=Beveridge T. J. |author2=Davies J. A. |title=Cellular responses of Bacillus subtilis and Escherichia coli to the Gram stain |journal=Journal of Bacteriology |volume=156 |issue=2 |pages=846–58 |date=November 1983 |pmid=6195148 |pmc=217903 |doi= |url=http://jb.asm.org/cgi/pmidlookup?view=long&pmid=6195148}}</ref><ref name="Davies_et_al_1983">{{cite journal |author1=Davies J. A. |author2=Anderson G. K. |author3=Beveridge T. J. |author4=Clark H. C. |title=Chemical mechanism of the Gram stain and synthesis of a new electron-opaque marker for electron microscopy, which replaces the iodine mordant of the stain |journal=Journal of Bacteriology |volume=156 |issue=2 |pages=837–845 |date=November 1983 |pmid=6195147 |pmc=217902 |doi= |url=http://jb.asm.org/cgi/pmidlookup?view=long&pmid=6195147}}</ref> Both Gram-positive bacteria and Gram-negative bacteria pick up the counterstain. The counterstain, however, is unseen on Gram-positive bacteria because of the darker crystal violet stain.'
] |
Parsed HTML source of the new revision (new_html) | '<div class="mw-parser-output"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Method of staining used to differentiate bacterial species into two large groups (Gram-positive and Gram-negative)</div>
<div class="thumb tright"><div class="thumbinner" style="width:222px;"><a href="/enwiki/wiki/File:Gram_stain_01.jpg" class="image"><img alt="" src="/upwiki/wikipedia/commons/thumb/8/8f/Gram_stain_01.jpg/220px-Gram_stain_01.jpg" decoding="async" width="220" height="165" class="thumbimage" srcset="/upwiki/wikipedia/commons/thumb/8/8f/Gram_stain_01.jpg/330px-Gram_stain_01.jpg 1.5x, /upwiki/wikipedia/commons/thumb/8/8f/Gram_stain_01.jpg/440px-Gram_stain_01.jpg 2x" data-file-width="1560" data-file-height="1170" /></a> <div class="thumbcaption"><div class="magnify"><a href="/enwiki/wiki/File:Gram_stain_01.jpg" class="internal" title="Enlarge"></a></div>A Gram stain of mixed <i><a href="/enwiki/wiki/Staphylococcus_aureus" title="Staphylococcus aureus">Staphylococcus aureus</a></i> (<i>S. aureus</i> ATCC 25923, Gram-positive cocci, in purple) and <i><a href="/enwiki/wiki/Escherichia_coli" title="Escherichia coli">Escherichia coli</a></i> (<i>E. coli</i> ATCC 11775, Gram-negative bacilli, in red), the most common Gram stain reference bacteria</div></div></div>
<p><b>Gram stain</b> or <b>Gram staining</b>, also called <b>Gram's method</b>, is a method of <a href="/enwiki/wiki/Staining" title="Staining">staining</a> used to distinguish and classify <a href="/enwiki/wiki/Bacteria" title="Bacteria">bacterial</a> species into two large groups (<a href="/enwiki/wiki/Gram-positive_bacteria" title="Gram-positive bacteria">Gram-positive</a> and <a href="/enwiki/wiki/Gram-negative_bacteria" title="Gram-negative bacteria">Gram-negative</a>). The name comes from the Danish <a href="/enwiki/wiki/Bacteriologist" class="mw-redirect" title="Bacteriologist">bacteriologist</a> <a href="/enwiki/wiki/Hans_Christian_Gram" title="Hans Christian Gram">Hans Christian Gram</a>, who developed the technique.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1">[1]</a></sup>
</p><p>Gram staining differentiates bacteria by the chemical and physical properties of their <a href="/enwiki/wiki/Cell_wall" title="Cell wall">cell walls</a>. Gram-positive cells have a thick layer of <a href="/enwiki/wiki/Peptidoglycan" title="Peptidoglycan">peptidoglycan</a> in the cell wall that retains the primary stain, <a href="/enwiki/wiki/Crystal_violet" title="Crystal violet">crystal violet</a>. Gram-negative cells have a thinner peptidoglycan layer that allows the crystal violet to wash out. They are stained pink by the <a href="/enwiki/wiki/Counterstain" title="Counterstain">counterstain</a>,<sup id="cite_ref-Beveridge_and_Davies_1983_2-0" class="reference"><a href="#cite_note-Beveridge_and_Davies_1983-2">[2]</a></sup> commonly <a href="/enwiki/wiki/Safranin" title="Safranin">safranin</a> or <a href="/enwiki/wiki/Fuchsine" title="Fuchsine">fuchsine</a>.
</p><p>The Gram stain is almost always the first step in the preliminary identification of a bacterial organism. While Gram staining is a valuable diagnostic tool in both clinical and research settings, not all bacteria can be definitively classified by this technique. This gives rise to <i>Gram-variable</i> and <i>Gram-indeterminate</i> groups.
</p>
<div id="toc" class="toc"><input type="checkbox" role="button" id="toctogglecheckbox" class="toctogglecheckbox" style="display:none" /><div class="toctitle" lang="en" dir="ltr"><h2>Contents</h2><span class="toctogglespan"><label class="toctogglelabel" for="toctogglecheckbox"></label></span></div>
<ul>
<li class="toclevel-1 tocsection-1"><a href="#History"><span class="tocnumber">1</span> <span class="toctext">History</span></a></li>
<li class="toclevel-1 tocsection-2"><a href="#Uses"><span class="tocnumber">2</span> <span class="toctext">Uses</span></a>
<ul>
<li class="toclevel-2 tocsection-3"><a href="#Medical"><span class="tocnumber">2.1</span> <span class="toctext">Medical</span></a></li>
</ul>
</li>
<li class="toclevel-1 tocsection-4"><a href="#Examples"><span class="tocnumber">3</span> <span class="toctext">Examples</span></a>
<ul>
<li class="toclevel-2 tocsection-5"><a href="#Gram-positive_bacteria"><span class="tocnumber">3.1</span> <span class="toctext">Gram-positive bacteria</span></a></li>
<li class="toclevel-2 tocsection-6"><a href="#Gram-negative_bacteria"><span class="tocnumber">3.2</span> <span class="toctext">Gram-negative bacteria</span></a></li>
<li class="toclevel-2 tocsection-7"><a href="#Gram-variable_and_Gram-indeterminate_bacteria"><span class="tocnumber">3.3</span> <span class="toctext">Gram-variable and Gram-indeterminate bacteria</span></a></li>
</ul>
</li>
<li class="toclevel-1 tocsection-8"><a href="#Orthographic_note"><span class="tocnumber">4</span> <span class="toctext">Orthographic note</span></a></li>
<li class="toclevel-1 tocsection-9"><a href="#See_also"><span class="tocnumber">5</span> <span class="toctext">See also</span></a></li>
<li class="toclevel-1 tocsection-10"><a href="#References"><span class="tocnumber">6</span> <span class="toctext">References</span></a></li>
<li class="toclevel-1 tocsection-11"><a href="#External_links"><span class="tocnumber">7</span> <span class="toctext">External links</span></a></li>
</ul>
</div>
<h2><span class="mw-headline" id="History">History</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Gram_stain&action=edit&section=1" title="Edit section: History">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<p>The method is named after its inventor, the <a href="/enwiki/wiki/Denmark" title="Denmark">Danish</a> scientist <a href="/enwiki/wiki/Hans_Christian_Gram" title="Hans Christian Gram">Hans Christian Gram</a> (1853–1938), who developed the technique while working with <a href="/enwiki/wiki/Carl_Friedl%C3%A4nder" title="Carl Friedländer">Carl Friedländer</a> in the morgue of the city hospital in <a href="/enwiki/wiki/Berlin" title="Berlin">Berlin</a> in 1884. Gram devised his technique not for the purpose of distinguishing one type of bacterium from another but to make bacteria more visible in stained sections of lung tissue.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3">[3]</a></sup> He published his method in 1884, and included in his short report the observation that the <a href="/enwiki/wiki/Typhus" title="Typhus">typhus</a> <a href="/enwiki/wiki/Bacillus_(shape)" title="Bacillus (shape)">bacillus</a> did not retain the stain.<sup id="cite_ref-Gram_1884_4-0" class="reference"><a href="#cite_note-Gram_1884-4">[4]</a></sup>
</p>
<h2><span class="mw-headline" id="Uses">Uses</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Gram_stain&action=edit&section=2" title="Edit section: Uses">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<p>Gram staining is a <a href="/enwiki/wiki/Bacteriology" title="Bacteriology">bacteriological</a> <a href="/enwiki/wiki/Laboratory" title="Laboratory">laboratory</a> technique<sup id="cite_ref-Sherris_5-0" class="reference"><a href="#cite_note-Sherris-5">[5]</a></sup> used to differentiate <a href="/enwiki/wiki/Bacterium" class="mw-redirect" title="Bacterium">bacterial</a> species into two large groups (<a href="/enwiki/wiki/Gram-positive" class="mw-redirect" title="Gram-positive">Gram-positive</a> and <a href="/enwiki/wiki/Gram-negative" class="mw-redirect" title="Gram-negative">Gram-negative</a>) based on the physical properties of their <a href="/enwiki/wiki/Cell_wall" title="Cell wall">cell walls</a>.<sup id="cite_ref-Madigan_2004_6-0" class="reference"><a href="#cite_note-Madigan_2004-6">[6]</a></sup><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/enwiki/wiki/Wikipedia:Citing_sources" title="Wikipedia:Citing sources"><span title="This citation requires a reference to the specific page or range of pages in which the material appears. (March 2016)">page needed</span></a></i>]</sup> Gram staining is not used to classify <a href="/enwiki/wiki/Archaea" title="Archaea">archaea</a>, formerly archaeabacteria, since these microorganisms yield widely varying responses that do not follow their <a href="/enwiki/wiki/Phylogenetics" title="Phylogenetics">phylogenetic groups</a>.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7">[7]</a></sup>
</p><p>The Gram stain is not an infallible tool for diagnosis, identification, or phylogeny, and it is of extremely limited use in <a href="/enwiki/wiki/Environmental_microbiology" class="mw-redirect" title="Environmental microbiology">environmental microbiology</a>. It is used mainly to make a preliminary morphologic identification or to establish that there are significant numbers of bacteria in a clinical specimen. It cannot identify bacteria to the species level, and for most medical conditions, it should not be used as the sole method of bacterial identification. In clinical microbiology laboratories, it is used in combination with other traditional and molecular techniques to identify bacteria. Some organisms are Gram-variable (meaning they may stain either negative or positive); some are not stained with either dye used in the Gram technique and are not seen. In a modern environmental or molecular microbiology lab, most identification is done using genetic sequences and other molecular techniques, which are far more specific and informative than differential staining.
</p><p>Gram staining has been suggested to be as effective a diagnostic tool as <a href="/enwiki/wiki/Polymerase_chain_reaction" title="Polymerase chain reaction">PCR</a> in one primary research report regarding gonococcal urethritis.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8">[8]</a></sup><sup class="noprint Inline-Template noprint Template-Fact" style="white-space:nowrap;">[<i><a href="/enwiki/wiki/Wikipedia:No_original_research#Primary,_secondary_and_tertiary_sources" title="Wikipedia:No original research"><span title="This claim needs references to reliable secondary sources. (March 2016)">non-primary source needed</span></a></i>]</sup>
</p>
<h3><span class="mw-headline" id="Medical">Medical</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Gram_stain&action=edit&section=3" title="Edit section: Medical">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<div role="note" class="hatnote navigation-not-searchable">See also: <a href="/enwiki/wiki/Gram-negative_bacterial_infection" title="Gram-negative bacterial infection">Gram-negative bacterial infection</a> and <a href="/enwiki/wiki/Gram-positive_bacterial_infection" class="mw-redirect" title="Gram-positive bacterial infection">Gram-positive bacterial infection</a></div>
<p>Gram stains are performed on <a href="/enwiki/wiki/Body_fluid" title="Body fluid">body fluid</a> or <a href="/enwiki/wiki/Biopsy" title="Biopsy">biopsy</a> when <a href="/enwiki/wiki/Infection" title="Infection">infection</a> is suspected. Gram stains yield results much more quickly than <a href="/enwiki/wiki/Microbiological_culture" title="Microbiological culture">culturing</a>, and is especially important when infection would make an important difference in the patient's treatment and prognosis; examples are <a href="/enwiki/wiki/Cerebrospinal_fluid" title="Cerebrospinal fluid">cerebrospinal fluid</a> for <a href="/enwiki/wiki/Meningitis" title="Meningitis">meningitis</a> and <a href="/enwiki/wiki/Synovial_fluid" title="Synovial fluid">synovial fluid</a> for <a href="/enwiki/wiki/Septic_arthritis" title="Septic arthritis">septic arthritis</a>.<sup id="cite_ref-Sherris_5-1" class="reference"><a href="#cite_note-Sherris-5">[5]</a></sup><sup id="cite_ref-Søgaard_2007_9-0" class="reference"><a href="#cite_note-Søgaard_2007-9">[9]</a></sup>
</p><p><br />
</p>
<pre>B. cereus is a common soil saprophyte and is easily spread to many types of foods, especially of plant origin, but is also frequently isolated from meat, eggs and dairy products. The development of psychrotrophic strains in the dairy industry has led to increasing surveillance of B. cereus in recent years. B. cereus food poisoning is underreported as both types of illness are relatively mild and usually last for less than 24 h. However, occasional reports have described a more severe form of the diarrhoeal type of B. cereus food poisoning.
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<p><span class="error mw-ext-cite-error" lang="en" dir="ltr">Cite error: There are <code><ref></code> tags on this page without content in them (see the <a href="/enwiki/wiki/Help:Cite_errors/Cite_error_ref_no_input" title="Help:Cite errors/Cite error ref no input">help page</a>).
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<h2><span class="mw-headline" id="Examples">Examples</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Gram_stain&action=edit&section=4" title="Edit section: Examples">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<h3><span class="mw-headline" id="Gram-positive_bacteria">Gram-positive bacteria</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Gram_stain&action=edit&section=5" title="Edit section: Gram-positive bacteria">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/enwiki/wiki/Gram-positive_bacteria" title="Gram-positive bacteria">Gram-positive bacteria</a></div>
<p>Gram-positive bacteria generally have a single membrane (<i>monoderm</i>) surrounded by a thick peptidoglycan.
This rule is followed by two phyla: <i><a href="/enwiki/wiki/Firmicutes" title="Firmicutes">Firmicutes</a></i> (except for the classes <a href="/enwiki/wiki/Mollicutes" title="Mollicutes">Mollicutes</a> and <a href="/enwiki/wiki/Negativicutes" title="Negativicutes">Negativicutes</a>) and the <i><a href="/enwiki/wiki/Actinobacteria" title="Actinobacteria">Actinobacteria</a></i>.<sup id="cite_ref-Madigan_2004_6-1" class="reference"><a href="#cite_note-Madigan_2004-6">[6]</a></sup><sup id="cite_ref-Begey_essay_10-0" class="reference"><a href="#cite_note-Begey_essay-10">[10]</a></sup> In contrast, members of the <a href="/enwiki/wiki/Chloroflexi_(phylum)" title="Chloroflexi (phylum)">Chloroflexi</a> (green non-sulfur bacteria) are monoderms but possess a thin or absent (class <a href="/enwiki/wiki/Dehalococcoidetes" title="Dehalococcoidetes">Dehalococcoidetes</a>) peptidoglycan and can stain negative, positive or indeterminate; members of the <a href="/enwiki/wiki/Deinococcus%E2%80%93Thermus" title="Deinococcus–Thermus"><i>Deinococcus–Thermus</i> group</a> stain positive but are diderms with a thick peptidoglycan.<sup id="cite_ref-Madigan_2004_6-2" class="reference"><a href="#cite_note-Madigan_2004-6">[6]</a></sup><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/enwiki/wiki/Wikipedia:Citing_sources" title="Wikipedia:Citing sources"><span title="This citation requires a reference to the specific page or range of pages in which the material appears. (March 2016)">page needed</span></a></i>]</sup><sup id="cite_ref-Begey_essay_10-1" class="reference"><a href="#cite_note-Begey_essay-10">[10]</a></sup>
</p><p><a href="/enwiki/wiki/Bacterial_taxonomy" title="Bacterial taxonomy">Historically</a>, the Gram-positive forms made up the <a href="/enwiki/wiki/Phylum_(biology)" class="mw-redirect" title="Phylum (biology)">phylum</a> <i><a href="/enwiki/wiki/Firmicutes" title="Firmicutes">Firmicutes</a></i>, a name now used for the largest group. It includes many well-known genera such as <i><a href="/enwiki/wiki/Bacillus" title="Bacillus">Bacillus</a></i>, <i><a href="/enwiki/wiki/Listeria" title="Listeria">Listeria</a></i>, <i><a href="/enwiki/wiki/Staphylococcus" title="Staphylococcus">Staphylococcus</a></i>, <i><a href="/enwiki/wiki/Streptococcus" title="Streptococcus">Streptococcus</a></i>, <i><a href="/enwiki/wiki/Enterococcus" title="Enterococcus">Enterococcus</a></i>, and <i><a href="/enwiki/wiki/Clostridium" title="Clostridium">Clostridium</a></i>.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11">[11]</a></sup><sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/enwiki/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2016)">citation needed</span></a></i>]</sup> It has also been expanded to include the <i>Mollicutes</i>, bacteria like <i><a href="/enwiki/wiki/Mycoplasma" title="Mycoplasma">Mycoplasma</a></i> that lack cell walls and so cannot be Gram-stained, but are derived from such forms.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12">[12]</a></sup><sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/enwiki/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2016)">citation needed</span></a></i>]</sup>
</p><p>Some bacteria have cell walls which are particularly adept at retaining stains. These will appear positive by Gram stain even though they are not closely related to other Gram-positive bacteria. These are called <a href="/enwiki/wiki/Acid-fastness" title="Acid-fastness">acid-fast bacteria</a>, and can only be differentiated from other Gram-positive bacteria by <a href="/enwiki/wiki/Ziehl%E2%80%93Neelsen_stain" title="Ziehl–Neelsen stain">special staining procedures</a>.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13">[13]</a></sup><sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/enwiki/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (March 2016)">citation needed</span></a></i>]</sup>
</p>
<h3><span class="mw-headline" id="Gram-negative_bacteria">Gram-negative bacteria</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Gram_stain&action=edit&section=6" title="Edit section: Gram-negative bacteria">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/enwiki/wiki/Gram-negative_bacteria" title="Gram-negative bacteria">Gram-negative bacteria</a></div>
<p>Gram-negative bacteria generally possess a thin layer of peptidoglycan between two membranes (<i>diderms</i>). Most <a href="/enwiki/wiki/Bacterial_phyla" title="Bacterial phyla">bacterial phyla</a> are Gram-negative, including the <a href="/enwiki/wiki/Cyanobacteria" title="Cyanobacteria">cyanobacteria</a>, <a href="/enwiki/wiki/Green_sulfur_bacteria" title="Green sulfur bacteria">green sulfur bacteria</a>, and most <i><a href="/enwiki/wiki/Proteobacteria" title="Proteobacteria">Proteobacteria</a></i> (exceptions being some members of the <i><a href="/enwiki/wiki/Rickettsiales" title="Rickettsiales">Rickettsiales</a></i> and the insect-endosymbionts of the <i><a href="/enwiki/wiki/Enterobacteriales" title="Enterobacteriales">Enterobacteriales</a></i>).<sup id="cite_ref-Madigan_2004_6-3" class="reference"><a href="#cite_note-Madigan_2004-6">[6]</a></sup><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/enwiki/wiki/Wikipedia:Citing_sources" title="Wikipedia:Citing sources"><span title="This citation requires a reference to the specific page or range of pages in which the material appears. (March 2016)">page needed</span></a></i>]</sup><sup id="cite_ref-Begey_essay_10-2" class="reference"><a href="#cite_note-Begey_essay-10">[10]</a></sup>
</p>
<h3><span class="mw-headline" id="Gram-variable_and_Gram-indeterminate_bacteria">Gram-variable and Gram-indeterminate bacteria</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Gram_stain&action=edit&section=7" title="Edit section: Gram-variable and Gram-indeterminate bacteria">edit</a><span class="mw-editsection-bracket">]</span></span></h3>
<p>Some bacteria, after staining with the Gram stain, yield a Gram-variable pattern: a mix of pink and purple cells are seen.<sup id="cite_ref-:0_14-0" class="reference"><a href="#cite_note-:0-14">[14]</a></sup><sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/enwiki/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (October 2015)">citation needed</span></a></i>]</sup> In cultures of Bacillus, Butyrivibrio, and Clostridium, a decrease in peptidoglycan thickness during growth coincides with an increase in the number of cells that stain Gram-negative.<sup id="cite_ref-Beveridge_1990_15-0" class="reference"><a href="#cite_note-Beveridge_1990-15">[15]</a></sup> In addition, in all bacteria stained using the Gram stain, the age of the culture may influence the results of the stain.<sup id="cite_ref-Beveridge_1990_15-1" class="reference"><a href="#cite_note-Beveridge_1990-15">[15]</a></sup>
</p><p>Gram-indeterminate bacteria do not respond predictably to Gram staining and, therefore, cannot be determined as either Gram-positive or Gram-negative. Examples include many species of <i><a href="/enwiki/wiki/Mycobacterium" title="Mycobacterium">Mycobacterium</a></i>, including <i><a href="/enwiki/wiki/Mycobacterium_tuberculosis" title="Mycobacterium tuberculosis">M. tuberculosis</a></i> and <i><a href="/enwiki/wiki/Mycobacterium_leprae" title="Mycobacterium leprae">M. leprae</a></i>.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16">[16]</a></sup><sup id="cite_ref-pmid19885935_17-0" class="reference"><a href="#cite_note-pmid19885935-17">[17]</a></sup>
</p>
<h2><span class="mw-headline" id="Orthographic_note">Orthographic note</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Gram_stain&action=edit&section=8" title="Edit section: Orthographic note">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<p>The term "Gram staining" is derived from the surname of <a href="/enwiki/wiki/Hans_Christian_Gram" title="Hans Christian Gram">Hans Christian Gram</a>; the <a href="/enwiki/wiki/Eponym" title="Eponym">eponym</a> (Gram) is therefore capitalized but not the common noun (stain) as is usual for scientific terms.<sup id="cite_ref-18" class="reference"><a href="#cite_note-18">[18]</a></sup> The initial letters of "Gram-positive" and "Gram-negative", which are <a href="/enwiki/wiki/Eponym#Orthographic_conventions" title="Eponym">eponymous adjectives</a>, can be either lowercase "g" or capital "G", depending on what <a href="/enwiki/wiki/Style_guide" title="Style guide">style guide</a> (if any) governs the document being written. Lowercase style is used by the US <a href="/enwiki/wiki/Centers_for_Disease_Control_and_Prevention" title="Centers for Disease Control and Prevention">Centers for Disease Control and Prevention</a> and other style regimens such as the <a href="/enwiki/wiki/AMA_style" class="mw-redirect" title="AMA style">AMA style</a>.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19">[19]</a></sup> Dictionaries may use lowercase,<sup id="cite_ref-Dorlands_20-0" class="reference"><a href="#cite_note-Dorlands-20">[20]</a></sup><sup id="cite_ref-MWMD_21-0" class="reference"><a href="#cite_note-MWMD-21">[21]</a></sup> uppercase,<sup id="cite_ref-22" class="reference"><a href="#cite_note-22">[22]</a></sup><sup id="cite_ref-23" class="reference"><a href="#cite_note-23">[23]</a></sup><sup id="cite_ref-24" class="reference"><a href="#cite_note-24">[24]</a></sup><sup id="cite_ref-25" class="reference"><a href="#cite_note-25">[25]</a></sup> or both.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26">[26]</a></sup><sup id="cite_ref-dictionary_27-0" class="reference"><a href="#cite_note-dictionary-27">[27]</a></sup> Uppercase 'Gram-positive' or 'Gram-negative' usage is also common in many <a href="/enwiki/wiki/Scientific_journal" title="Scientific journal">scientific journal</a> articles and publications.<sup id="cite_ref-dictionary_27-1" class="reference"><a href="#cite_note-dictionary-27">[27]</a></sup><sup id="cite_ref-28" class="reference"><a href="#cite_note-28">[28]</a></sup><sup id="cite_ref-29" class="reference"><a href="#cite_note-29">[29]</a></sup> When articles are submitted to journals, each journal may or may not apply house style to the <a href="/enwiki/wiki/Postprint" title="Postprint">postprint</a> version. <a href="/enwiki/wiki/Preprint" title="Preprint">Preprint</a> versions contain whichever style the author happened to use. Even style regimens that use lowercase for the adjectives "gram-positive" and "gram-negative" still use capital for "Gram stain".
</p>
<h2><span class="mw-headline" id="See_also">See also</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Gram_stain&action=edit&section=9" title="Edit section: See also">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<ul><li><a href="/enwiki/wiki/Bacterial_cell_structure" title="Bacterial cell structure">Bacterial cell structure</a></li>
<li><a href="/enwiki/wiki/Ziehl%E2%80%93Neelsen_stain" title="Ziehl–Neelsen stain">Ziehl–Neelsen stain </a></li></ul>
<h2><span class="mw-headline" id="References">References</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Gram_stain&action=edit&section=10" title="Edit section: References">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<div class="reflist" style="list-style-type: decimal;">
<div class="mw-references-wrap mw-references-columns"><ol class="references">
<li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><cite class="citation journal">Colco, R (2005). "Gram Staining". <i>Current Protocols in Microbiology</i>. <b>00</b> (1): Appendix 3C. <a href="/enwiki/wiki/Digital_object_identifier" title="Digital object identifier">doi</a>:<a rel="nofollow" class="external text" href="/enwiki//doi.org/10.1002%2F9780471729259.mca03cs00">10.1002/9780471729259.mca03cs00</a>. <a href="/enwiki/wiki/International_Standard_Book_Number" title="International Standard Book Number">ISBN</a> <a href="/enwiki/wiki/Special:BookSources/978-0471729259" title="Special:BookSources/978-0471729259"><bdi>978-0471729259</bdi></a>. <a href="/enwiki/wiki/PubMed_Identifier" class="mw-redirect" title="PubMed Identifier">PMID</a> <a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pubmed/18770544">18770544</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Current+Protocols+in+Microbiology&rft.atitle=Gram+Staining&rft.volume=00&rft.issue=1&rft.pages=Appendix+3C&rft.date=2005&rft_id=info%3Apmid%2F18770544&rft_id=info%3Adoi%2F10.1002%2F9780471729259.mca03cs00&rft.isbn=978-0471729259&rft.aulast=Colco&rft.aufirst=R&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><style data-mw-deduplicate="TemplateStyles:r886058088">.mw-parser-output cite.citation{font-style:inherit}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation .cs1-lock-free a{background:url("/upwiki/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .citation .cs1-lock-limited a,.mw-parser-output .citation .cs1-lock-registration a{background:url("/upwiki/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .citation .cs1-lock-subscription a{background:url("/upwiki/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-ws-icon a{background:url("/upwiki/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/12px-Wikisource-logo.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-maint{display:none;color:#33aa33;margin-left:0.3em}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}</style></span>
</li>
<li id="cite_note-Beveridge_and_Davies_1983-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-Beveridge_and_Davies_1983_2-0">^</a></b></span> <span class="error mw-ext-cite-error" lang="en" dir="ltr">Cite error: The named reference <code>Beveridge_and_Davies_1983</code> was invoked but never defined (see the <a href="/enwiki/wiki/Help:Cite_errors/Cite_error_references_no_text" title="Help:Cite errors/Cite error references no text">help page</a>).
</span></li>
<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><cite class="citation journal">Austrian, R. (1960). <a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pmc/articles/PMC441053">"The Gram stain and the etiology of lobar pneumonia, an historical note"</a>. <i>Bacteriological Reviews</i>. <b>24</b> (3): 261–265. <a href="/enwiki/wiki/PubMed_Central" title="PubMed Central">PMC</a> <span class="cs1-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pmc/articles/PMC441053">441053</a></span>. <a href="/enwiki/wiki/PubMed_Identifier" class="mw-redirect" title="PubMed Identifier">PMID</a> <a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pubmed/13685217">13685217</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Bacteriological+Reviews&rft.atitle=The+Gram+stain+and+the+etiology+of+lobar+pneumonia%2C+an+historical+note&rft.volume=24&rft.issue=3&rft.pages=261-265&rft.date=1960&rft_id=%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC441053&rft_id=info%3Apmid%2F13685217&rft.aulast=Austrian&rft.aufirst=R.&rft_id=%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC441053&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-Gram_1884-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-Gram_1884_4-0">^</a></b></span> <span class="reference-text"><cite class="citation journal"><a href="/enwiki/wiki/Hans_Christian_Gram" title="Hans Christian Gram">Gram, H.C.</a> (1884). "Über die isolierte Färbung der Schizomyceten in Schnitt- und Trockenpräparaten". <i>Fortschritte der Medizin</i> (in German). <b>2</b>: 185–189.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Fortschritte+der+Medizin&rft.atitle=%C3%9Cber+die+isolierte+F%C3%A4rbung+der+Schizomyceten+in+Schnitt-+und+Trockenpr%C3%A4paraten&rft.volume=2&rft.pages=185-189&rft.date=1884&rft.aulast=Gram&rft.aufirst=H.C.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/>.<br />English translation in: <cite class="citation book">Brock, T.D. (1999). <a rel="nofollow" class="external text" href="https://books.google.com/?id=q5JHcs8w21gC&lpg=PP1&dq=Milestones%20in%20Microbiology&pg=PA215#v=onepage&q"><i>Milestones in Microbiology 1546–1940</i></a> (2 ed.). ASM Press. pp. 215–218. <a href="/enwiki/wiki/International_Standard_Book_Number" title="International Standard Book Number">ISBN</a> <a href="/enwiki/wiki/Special:BookSources/978-1-55581-142-6" title="Special:BookSources/978-1-55581-142-6"><bdi>978-1-55581-142-6</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Milestones+in+Microbiology+1546%E2%80%931940&rft.pages=215-218&rft.edition=2&rft.pub=ASM+Press&rft.date=1999&rft.isbn=978-1-55581-142-6&rft.aulast=Brock&rft.aufirst=T.D.&rft_id=https%3A%2F%2Fbooks.google.com%2F%3Fid%3Dq5JHcs8w21gC%26lpg%3DPP1%26dq%3DMilestones%2520in%2520Microbiology%26pg%3DPA215%23v%3Donepage%26q&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/><br />Translation is also at: <cite class="citation journal">Brock, T.D. <a rel="nofollow" class="external text" href="http://www.hoslink.com/pathology/lab_general/history2.htm#gram">"Pioneers in Medical Laboratory Science: Christian Gram 1884"</a>. Hoslink<span class="reference-accessdate">. Retrieved <span class="nowrap">2010-07-27</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=Pioneers+in+Medical+Laboratory+Science%3A+Christian+Gram+1884&rft.aulast=Brock&rft.aufirst=T.D.&rft_id=http%3A%2F%2Fwww.hoslink.com%2Fpathology%2Flab_general%2Fhistory2.htm%23gram&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span> <span class="cs1-hidden-error error citation-comment">Cite journal requires <code class="cs1-code">|journal=</code> (<a href="/enwiki/wiki/Help:CS1_errors#missing_periodical" title="Help:CS1 errors">help</a>)</span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-Sherris-5"><span class="mw-cite-backlink">^ <a href="#cite_ref-Sherris_5-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Sherris_5-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite class="citation book">Ryan K.J., Ray C.G. (editors) (2004). <i>Sherris Medical Microbiology</i> (4th ed.). McGraw Hill. pp. 232f. <a href="/enwiki/wiki/International_Standard_Book_Number" title="International Standard Book Number">ISBN</a> <a href="/enwiki/wiki/Special:BookSources/978-0838585290" title="Special:BookSources/978-0838585290"><bdi>978-0838585290</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Sherris+Medical+Microbiology&rft.pages=232f&rft.edition=4th&rft.pub=McGraw+Hill&rft.date=2004&rft.isbn=978-0838585290&rft.au=Ryan+K.J.%2C+Ray+C.G.+%28editors%29&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><span class="cs1-maint citation-comment">CS1 maint: extra text: authors list (<a href="/enwiki/wiki/Category:CS1_maint:_extra_text:_authors_list" title="Category:CS1 maint: extra text: authors list">link</a>)</span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/enwiki/wiki/Wikipedia:Citing_sources#What_information_to_include" title="Wikipedia:Citing sources"><span title="A complete citation is needed (March 2016)">full citation needed</span></a></i>]</sup></span>
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<li id="cite_note-Madigan_2004-6"><span class="mw-cite-backlink">^ <a href="#cite_ref-Madigan_2004_6-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Madigan_2004_6-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Madigan_2004_6-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Madigan_2004_6-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><cite class="citation book">Madigan, M.T.; Martinko J.; Parker J. (2004). <span class="cs1-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/brockbiologyofmi00madi"><i>Brock Biology of Microorganisms</i></a></span> (10th ed.). Lippincott Williams & Wilkins. <a href="/enwiki/wiki/International_Standard_Book_Number" title="International Standard Book Number">ISBN</a> <a href="/enwiki/wiki/Special:BookSources/978-0-13-066271-2" title="Special:BookSources/978-0-13-066271-2"><bdi>978-0-13-066271-2</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Brock+Biology+of+Microorganisms&rft.edition=10th&rft.pub=Lippincott+Williams+%26+Wilkins&rft.date=2004&rft.isbn=978-0-13-066271-2&rft.aulast=Madigan&rft.aufirst=M.T.&rft.au=Martinko+J.&rft.au=Parker+J.&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fbrockbiologyofmi00madi&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/enwiki/wiki/Wikipedia:Citing_sources#What_information_to_include" title="Wikipedia:Citing sources"><span title="A complete citation is needed (March 2016)">full citation needed</span></a></i>]</sup></span>
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<li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><cite class="citation journal">Beveridge T.J. (2001). "Use of the Gram stain in microbiology". <i>Biotechnic & Histochemistry</i>. <b>76</b> (3): 111–118. <a href="/enwiki/wiki/Digital_object_identifier" title="Digital object identifier">doi</a>:<a rel="nofollow" class="external text" href="/enwiki//doi.org/10.1080%2F714028139">10.1080/714028139</a>. <a href="/enwiki/wiki/PubMed_Identifier" class="mw-redirect" title="PubMed Identifier">PMID</a> <a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pubmed/11475313">11475313</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Biotechnic+%26+Histochemistry&rft.atitle=Use+of+the+Gram+stain+in+microbiology&rft.volume=76&rft.issue=3&rft.pages=111-118&rft.date=2001&rft_id=info%3Adoi%2F10.1080%2F714028139&rft_id=info%3Apmid%2F11475313&rft.au=Beveridge+T.J.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text">El-Garnal, A.H., Al-Otaibi, S.R., Alshamali, A., Abdulrazzaq, A., Najem, N., and Fouzan, A.A. Polymerase chain reaction is no better than Gram stain for diagnosis of gonococcal urethritis. Indian Journal of Dermatology, Venereology and Leprology, (2009); 75, 101.<sup class="noprint Inline-Template noprint Template-Fact" style="white-space:nowrap;">[<i><a href="/enwiki/wiki/Wikipedia:No_original_research#Primary,_secondary_and_tertiary_sources" title="Wikipedia:No original research"><span title="This claim needs references to reliable secondary sources. (March 2016)">non-primary source needed</span></a></i>]</sup></span>
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<li id="cite_note-Søgaard_2007-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-Søgaard_2007_9-0">^</a></b></span> <span class="reference-text"><cite class="citation journal">Søgaard M.; Nørgaard M.; Schønheyder H. (2007). <a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pmc/articles/PMC1865800">"First notification of positive blood cultures: high accuracy of the Gram stain report"</a>. <i>Journal of Clinical Microbiology</i>. <b>45</b> (4): 1113–1117. <a href="/enwiki/wiki/Digital_object_identifier" title="Digital object identifier">doi</a>:<a rel="nofollow" class="external text" href="/enwiki//doi.org/10.1128%2FJCM.02523-06">10.1128/JCM.02523-06</a>. <a href="/enwiki/wiki/PubMed_Central" title="PubMed Central">PMC</a> <span class="cs1-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pmc/articles/PMC1865800">1865800</a></span>. <a href="/enwiki/wiki/PubMed_Identifier" class="mw-redirect" title="PubMed Identifier">PMID</a> <a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pubmed/17301283">17301283</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Clinical+Microbiology&rft.atitle=First+notification+of+positive+blood+cultures%3A+high+accuracy+of+the+Gram+stain+report&rft.volume=45&rft.issue=4&rft.pages=1113-1117&rft.date=2007&rft_id=%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC1865800&rft_id=info%3Apmid%2F17301283&rft_id=info%3Adoi%2F10.1128%2FJCM.02523-06&rft.au=S%C3%B8gaard+M.&rft.au=N%C3%B8rgaard+M.&rft.au=Sch%C3%B8nheyder+H.&rft_id=%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC1865800&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-Begey_essay-10"><span class="mw-cite-backlink">^ <a href="#cite_ref-Begey_essay_10-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Begey_essay_10-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Begey_essay_10-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><cite class="citation book">Don J. Brenner, Noel R. Krieg, James T. Staley (July 26, 2005) [1984]. George M. Garrity (ed.). <a rel="nofollow" class="external text" href="https://www.springer.com/life+sciences/book/978-0-387-24143-2"><i>Introductory Essays</i></a>. Bergey's Manual of Systematic Bacteriology. <b>2A</b> (2nd ed.). New York: Springer. p. 304. <a href="/enwiki/wiki/International_Standard_Book_Number" title="International Standard Book Number">ISBN</a> <a href="/enwiki/wiki/Special:BookSources/978-0-387-24143-2" title="Special:BookSources/978-0-387-24143-2"><bdi>978-0-387-24143-2</bdi></a>. British Library no. GBA561951.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Introductory+Essays&rft.place=New+York&rft.series=Bergey%27s+Manual+of+Systematic+Bacteriology&rft.pages=304&rft.edition=2nd&rft.pub=Springer&rft.date=2005-07-26&rft.isbn=978-0-387-24143-2&rft_id=https%3A%2F%2Fwww.springer.com%2Flife%2Bsciences%2Fbook%2F978-0-387-24143-2&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><span class="cs1-maint citation-comment">CS1 maint: uses authors parameter (<a href="/enwiki/wiki/Category:CS1_maint:_uses_authors_parameter" title="Category:CS1 maint: uses authors parameter">link</a>)</span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/><sup class="noprint Inline-Template" style="white-space:nowrap;">[<i><a href="/enwiki/wiki/Wikipedia:Citing_sources" title="Wikipedia:Citing sources"><span title="This citation requires a reference to the specific page or range of pages in which the material appears. (October 2013)">page needed</span></a></i>]</sup></span>
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<li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><cite class="citation journal">Galperin, Michael Y. (2013-12-27). <a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pmc/articles/PMC4306282">"Genome Diversity of Spore-Forming Firmicutes"</a>. <i>Microbiology Spectrum</i>. <b>1</b> (2). <a href="/enwiki/wiki/Digital_object_identifier" title="Digital object identifier">doi</a>:<a rel="nofollow" class="external text" href="/enwiki//doi.org/10.1128%2Fmicrobiolspectrum.tbs-0015-2012">10.1128/microbiolspectrum.tbs-0015-2012</a>. <a href="/enwiki/wiki/International_Standard_Serial_Number" title="International Standard Serial Number">ISSN</a> <a rel="nofollow" class="external text" href="/enwiki//www.worldcat.org/issn/2165-0497">2165-0497</a>. <a href="/enwiki/wiki/PubMed_Central" title="PubMed Central">PMC</a> <span class="cs1-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pmc/articles/PMC4306282">4306282</a></span>. <a href="/enwiki/wiki/PubMed_Identifier" class="mw-redirect" title="PubMed Identifier">PMID</a> <a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pubmed/26184964">26184964</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Microbiology+Spectrum&rft.atitle=Genome+Diversity+of+Spore-Forming+Firmicutes&rft.volume=1&rft.issue=2&rft.date=2013-12-27&rft_id=%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC4306282&rft.issn=2165-0497&rft_id=info%3Apmid%2F26184964&rft_id=info%3Adoi%2F10.1128%2Fmicrobiolspectrum.tbs-0015-2012&rft.aulast=Galperin&rft.aufirst=Michael+Y.&rft_id=%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC4306282&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text">Practical Medical Microbiology by Hams H. Hashem, from <a rel="nofollow" class="external free" href="http://qu.edu.iq/el/mod/resource/view.php?id=1391">http://qu.edu.iq/el/mod/resource/view.php?id=1391</a></span>
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<li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www2.highlands.edu/academics/divisions/scipe/biology/labs/rome/acid_fast_stain.htm">"The Acid Fast Stain"</a>. <i>www2.highlands.edu</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2017-06-09</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www2.highlands.edu&rft.atitle=The+Acid+Fast+Stain&rft_id=http%3A%2F%2Fwww2.highlands.edu%2Facademics%2Fdivisions%2Fscipe%2Fbiology%2Flabs%2Frome%2Facid_fast_stain.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-:0-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-:0_14-0">^</a></b></span> <span class="error mw-ext-cite-error" lang="en" dir="ltr">Cite error: The named reference <code>:0</code> was invoked but never defined (see the <a href="/enwiki/wiki/Help:Cite_errors/Cite_error_references_no_text" title="Help:Cite errors/Cite error references no text">help page</a>).
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<li id="cite_note-Beveridge_1990-15"><span class="mw-cite-backlink">^ <a href="#cite_ref-Beveridge_1990_15-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Beveridge_1990_15-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite class="citation journal">Beveridge, Terry J. (March 1990). <a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pmc/articles/PMC208639">"Mechanism of gram variability in select bacteria"</a>. <i>Journal of Bacteriology</i>. <b>172</b> (3): 1609–20. <a href="/enwiki/wiki/Digital_object_identifier" title="Digital object identifier">doi</a>:<a rel="nofollow" class="external text" href="/enwiki//doi.org/10.1128%2Fjb.172.3.1609-1620.1990">10.1128/jb.172.3.1609-1620.1990</a>. <a href="/enwiki/wiki/PubMed_Central" title="PubMed Central">PMC</a> <span class="cs1-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pmc/articles/PMC208639">208639</a></span>. <a href="/enwiki/wiki/PubMed_Identifier" class="mw-redirect" title="PubMed Identifier">PMID</a> <a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pubmed/1689718">1689718</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Bacteriology&rft.atitle=Mechanism+of+gram+variability+in+select+bacteria&rft.volume=172&rft.issue=3&rft.pages=1609-20&rft.date=1990-03&rft_id=%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC208639&rft_id=info%3Apmid%2F1689718&rft_id=info%3Adoi%2F10.1128%2Fjb.172.3.1609-1620.1990&rft.aulast=Beveridge&rft.aufirst=Terry+J.&rft_id=%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC208639&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text"><cite class="citation book">Black, Jacquelyn (2012). <i>Microbiology: Principles and Exploration</i> (8th ed.). John Wiley & Sons. p. 68. <a href="/enwiki/wiki/International_Standard_Book_Number" title="International Standard Book Number">ISBN</a> <a href="/enwiki/wiki/Special:BookSources/978-0-470-54109-8" title="Special:BookSources/978-0-470-54109-8"><bdi>978-0-470-54109-8</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Microbiology%3A+Principles+and+Exploration&rft.pages=68&rft.edition=8th&rft.pub=John+Wiley+%26+Sons&rft.date=2012&rft.isbn=978-0-470-54109-8&rft.aulast=Black&rft.aufirst=Jacquelyn&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-pmid19885935-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-pmid19885935_17-0">^</a></b></span> <span class="reference-text"><cite class="citation journal">Reynolds J.; Moyes R.B.; Breakwell D.P. (2009). "Differential staining of bacteria: acid fast stain". <i><a href="/enwiki/wiki/Current_Protocols#Titles" title="Current Protocols">Current Protocols in Microbiology</a></i>. Appendix 3: Appendix 3H. <a href="/enwiki/wiki/Digital_object_identifier" title="Digital object identifier">doi</a>:<a rel="nofollow" class="external text" href="/enwiki//doi.org/10.1002%2F9780471729259.mca03hs15">10.1002/9780471729259.mca03hs15</a>. <a href="/enwiki/wiki/International_Standard_Book_Number" title="International Standard Book Number">ISBN</a> <a href="/enwiki/wiki/Special:BookSources/978-0471729259" title="Special:BookSources/978-0471729259"><bdi>978-0471729259</bdi></a>. <a href="/enwiki/wiki/PubMed_Identifier" class="mw-redirect" title="PubMed Identifier">PMID</a> <a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pubmed/19885935">19885935</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Current+Protocols+in+Microbiology&rft.atitle=Differential+staining+of+bacteria%3A+acid+fast+stain&rft.volume=Appendix+3&rft.pages=Appendix+3H&rft.date=2009&rft_id=info%3Apmid%2F19885935&rft_id=info%3Adoi%2F10.1002%2F9780471729259.mca03hs15&rft.isbn=978-0471729259&rft.au=Reynolds+J.&rft.au=Moyes+R.B.&rft.au=Breakwell+D.P.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-18">^</a></b></span> <span class="reference-text"><cite class="citation book">Waddingham, Anne (28 August 2014). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=btb1AwAAQBAJ&pg=PA105"><i>New Hart's Rules: The Oxford Style Guide</i></a>. OUP Oxford. p. 105. <a href="/enwiki/wiki/International_Standard_Book_Number" title="International Standard Book Number">ISBN</a> <a href="/enwiki/wiki/Special:BookSources/978-0199570027" title="Special:BookSources/978-0199570027"><bdi>978-0199570027</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=New+Hart%27s+Rules%3A+The+Oxford+Style+Guide&rft.pages=105&rft.pub=OUP+Oxford&rft.date=2014-08-28&rft.isbn=978-0199570027&rft.aulast=Waddingham&rft.aufirst=Anne&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3Dbtb1AwAAQBAJ%26pg%3DPA105&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text">Centers for Disease Control and Prevention. Emerging Infectious Diseases Journal Style Guide. <a rel="nofollow" class="external text" href="http://wwwnc.cdc.gov/eid/pages/preferred-usage.htm">Preferred Usage</a></span>
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<li id="cite_note-Dorlands-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-Dorlands_20-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFElsevier" class="citation"><a href="/enwiki/wiki/Elsevier" title="Elsevier">Elsevier</a>, <a rel="nofollow" class="external text" href="http://www.dorlands.com/"><i>Dorland's Illustrated Medical Dictionary</i></a>, Elsevier.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Dorland%27s+Illustrated+Medical+Dictionary&rft.pub=Elsevier&rft.au=Elsevier&rft_id=http%3A%2F%2Fwww.dorlands.com%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-MWMD-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-MWMD_21-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFMerriam-Webster" class="citation"><a href="/enwiki/wiki/Merriam-Webster" title="Merriam-Webster">Merriam-Webster</a>, <a rel="nofollow" class="external text" href="http://www.merriam-webster.com/dictionary/gram%E2%80%93positive"><i>gram–positive</i></a>, Merriam-Webster.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=gram%E2%80%93positive&rft.pub=Merriam-Webster&rft.au=Merriam-Webster&rft_id=http%3A%2F%2Fwww.merriam-webster.com%2Fdictionary%2Fgram%25E2%2580%2593positive&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.collinsdictionary.com/dictionary/english/gram-positive">"Definition of Gram-positive"</a>. <i>Collins</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Collins&rft.atitle=Definition+of+Gram-positive&rft_id=http%3A%2F%2Fwww.collinsdictionary.com%2Fdictionary%2Fenglish%2Fgram-positive&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-23">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="https://en.oxforddictionaries.com/definition/gram_stain">"Gram stain"</a>. <i>Oxford Dictionary</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Oxford+Dictionary&rft.atitle=Gram+stain&rft_id=https%3A%2F%2Fen.oxforddictionaries.com%2Fdefinition%2Fgram_stain&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.medicinenet.com/script/main/art.asp?articlekey=9585">"Definition of Gram-positive"</a>. <i>Medicinenet</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Medicinenet&rft.atitle=Definition+of+Gram-positive&rft_id=http%3A%2F%2Fwww.medicinenet.com%2Fscript%2Fmain%2Fart.asp%3Farticlekey%3D9585&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.businessdictionary.com/definition/Gram-negative-positive.html">"Gram negative/positive"</a>. <i>Business dictionary</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Business+dictionary&rft.atitle=Gram+negative%2Fpositive&rft_id=http%3A%2F%2Fwww.businessdictionary.com%2Fdefinition%2FGram-negative-positive.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-26">^</a></b></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="https://ahdictionary.com/word/search.html?q=gram+positive&submit.x=0&submit.y=0">"gram-pos·i·tive or Gram-pos·i·tive"</a>. <i>The American Heritage Dictionary</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=The+American+Heritage+Dictionary&rft.atitle=gram-pos%C2%B7i%C2%B7tive+or+Gram-pos%C2%B7i%C2%B7tive&rft_id=https%3A%2F%2Fahdictionary.com%2Fword%2Fsearch.html%3Fq%3Dgram%2Bpositive%26submit.x%3D0%26submit.y%3D0&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-dictionary-27"><span class="mw-cite-backlink">^ <a href="#cite_ref-dictionary_27-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-dictionary_27-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite class="citation web"><a rel="nofollow" class="external text" href="http://www.dictionary.com/browse/gram-positive">"Gram-positive"</a>. <i>Dictionary.com</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Dictionary.com&rft.atitle=Gram-positive&rft_id=http%3A%2F%2Fwww.dictionary.com%2Fbrowse%2Fgram-positive&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
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<li id="cite_note-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-28">^</a></b></span> <span class="reference-text"><cite class="citation journal">Lisa Brown, Julie M. Wolf, Rafael Prados-Rosales & Arturo Casadevall (2015). <a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pmc/articles/PMC4860279">"Through the wall: extracellular vesicles in Gram-positive bacteria, mycobacteria and fungi"</a>. <i>Nature Reviews Microbiology</i>. <b>13</b> (10): 620–630. <a href="/enwiki/wiki/Digital_object_identifier" title="Digital object identifier">doi</a>:<a rel="nofollow" class="external text" href="/enwiki//doi.org/10.1038%2Fnrmicro3480">10.1038/nrmicro3480</a>. <a href="/enwiki/wiki/PubMed_Central" title="PubMed Central">PMC</a> <span class="cs1-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pmc/articles/PMC4860279">4860279</a></span>. <a href="/enwiki/wiki/PubMed_Identifier" class="mw-redirect" title="PubMed Identifier">PMID</a> <a rel="nofollow" class="external text" href="/enwiki//www.ncbi.nlm.nih.gov/pubmed/26324094">26324094</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Nature+Reviews+Microbiology&rft.atitle=Through+the+wall%3A+extracellular+vesicles+in+Gram-positive+bacteria%2C+mycobacteria+and+fungi&rft.volume=13&rft.issue=10&rft.pages=620-630&rft.date=2015&rft_id=%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC4860279&rft_id=info%3Apmid%2F26324094&rft_id=info%3Adoi%2F10.1038%2Fnrmicro3480&rft_id=%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC4860279&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><span class="cs1-maint citation-comment">CS1 maint: uses authors parameter (<a href="/enwiki/wiki/Category:CS1_maint:_uses_authors_parameter" title="Category:CS1 maint: uses authors parameter">link</a>)</span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
</li>
<li id="cite_note-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-29">^</a></b></span> <span class="reference-text"><cite class="citation journal">Kristen L. Mueller (12 June 2015). "Detecting Gram-negative bacteria". <i>Science</i>. <b>348</b> (6240): 1218. <a href="/enwiki/wiki/Digital_object_identifier" title="Digital object identifier">doi</a>:<a rel="nofollow" class="external text" href="/enwiki//doi.org/10.1126%2Fscience.348.6240.1218-o">10.1126/science.348.6240.1218-o</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Science&rft.atitle=Detecting+Gram-negative+bacteria&rft.volume=348&rft.issue=6240&rft.pages=1218&rft.date=2015-06-12&rft_id=info%3Adoi%2F10.1126%2Fscience.348.6240.1218-o&rft.au=Kristen+L.+Mueller&rfr_id=info%3Asid%2Fen.wikipedia.org%3AGram+stain" class="Z3988"></span><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886058088"/></span>
</li>
</ol></div></div>
<h2><span class="mw-headline" id="External_links">External links</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/enwiki/w/index.php?title=Gram_stain&action=edit&section=11" title="Edit section: External links">edit</a><span class="mw-editsection-bracket">]</span></span></h2>
<table role="presentation" class="mbox-small plainlinks sistersitebox" style="background-color:#f9f9f9;border:1px solid #aaa;color:#000">
<tbody><tr>
<td class="mbox-image"><img alt="" src="/upwiki/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png" decoding="async" width="30" height="40" class="noviewer" srcset="/upwiki/wikipedia/en/thumb/4/4a/Commons-logo.svg/45px-Commons-logo.svg.png 1.5x, /upwiki/wikipedia/en/thumb/4/4a/Commons-logo.svg/59px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></td>
<td class="mbox-text plainlist">Wikimedia Commons has media related to <i><b><a href="https://commons.wikimedia.org/wiki/Category:Gram_stains" class="extiw" title="commons:Category:Gram stains">Gram stains</a></b></i>.</td></tr>
</tbody></table>
<table role="presentation" class="mbox-small plainlinks sistersitebox" style="background-color:#f9f9f9;border:1px solid #aaa;color:#000">
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<td class="mbox-image"><img alt="" src="/upwiki/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/40px-Wikibooks-logo-en-noslogan.svg.png" decoding="async" width="40" height="40" class="noviewer" srcset="/upwiki/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/60px-Wikibooks-logo-en-noslogan.svg.png 1.5x, /upwiki/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/80px-Wikibooks-logo-en-noslogan.svg.png 2x" data-file-width="400" data-file-height="400" /></td>
<td class="mbox-text plainlist">The Wikibook <i><a href="https://en.wikibooks.org/wiki/School_Science" class="extiw" title="wikibooks:School Science">School Science</a></i> has a page on the topic of: <i><b><a href="https://en.wikibooks.org/wiki/School_Science/Gram_staining" class="extiw" title="wikibooks:School Science/Gram staining">Gram staining</a></b></i></td></tr>
</tbody></table>
<ul><li><a rel="nofollow" class="external text" href="http://www.tgw1916.net/movies.html">Gram staining technique video</a></li></ul>
<div role="navigation" class="navbox" aria-labelledby="Microbial_and_histological_stains" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div class="plainlinks hlist navbar mini"><ul><li class="nv-view"><a href="/enwiki/wiki/Template:Stains" title="Template:Stains"><abbr title="View this template" style=";;background:none transparent;border:none;-moz-box-shadow:none;-webkit-box-shadow:none;box-shadow:none; padding:0;">v</abbr></a></li><li class="nv-talk"><a href="/enwiki/wiki/Template_talk:Stains" title="Template talk:Stains"><abbr title="Discuss this template" style=";;background:none transparent;border:none;-moz-box-shadow:none;-webkit-box-shadow:none;box-shadow:none; padding:0;">t</abbr></a></li><li class="nv-edit"><a class="external text" href="https://en.wikipedia.org/enwiki/w/index.php?title=Template:Stains&action=edit"><abbr title="Edit this template" style=";;background:none transparent;border:none;-moz-box-shadow:none;-webkit-box-shadow:none;box-shadow:none; padding:0;">e</abbr></a></li></ul></div><div id="Microbial_and_histological_stains" style="font-size:114%;margin:0 4em"><a href="/enwiki/wiki/Staining" title="Staining">Microbial and histological stains</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/enwiki/wiki/Iron" title="Iron">Iron</a>/<a href="/enwiki/wiki/Hemosiderin" title="Hemosiderin">hemosiderin</a></th><td class="navbox-list navbox-odd hlist" style="text-align:left;border-left-width:2px;border-left-style:solid;width:100%;padding:0px"><div style="padding:0em 0.25em">
<ul><li><a href="/enwiki/wiki/Perls%27_Prussian_blue" title="Perls' Prussian blue">Perls' Prussian blue</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/enwiki/wiki/Lipid" title="Lipid">Lipids</a></th><td class="navbox-list navbox-even hlist" style="text-align:left;border-left-width:2px;border-left-style:solid;width:100%;padding:0px"><div style="padding:0em 0.25em">
<ul><li><a href="/enwiki/wiki/Sudan_stain" title="Sudan stain">Sudan stain</a>
<ul><li><a href="/enwiki/wiki/Sudan_II" title="Sudan II">Sudan II</a></li>
<li><a href="/enwiki/wiki/Sudan_III" title="Sudan III">Sudan III</a></li>
<li><a href="/enwiki/wiki/Sudan_IV" title="Sudan IV">Sudan IV</a></li>
<li><a href="/enwiki/wiki/Oil_Red_O" title="Oil Red O">Oil Red O</a></li>
<li><a href="/enwiki/wiki/Sudan_Black_B" title="Sudan Black B">Sudan Black B</a></li></ul></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/enwiki/wiki/Carbohydrate" title="Carbohydrate">Carbohydrates</a></th><td class="navbox-list navbox-odd hlist" style="text-align:left;border-left-width:2px;border-left-style:solid;width:100%;padding:0px"><div style="padding:0em 0.25em">
<ul><li><a href="/enwiki/wiki/Periodic_acid%E2%80%93Schiff_stain" title="Periodic acid–Schiff stain">Periodic acid–Schiff stain</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/enwiki/wiki/Amyloid" title="Amyloid">Amyloid</a></th><td class="navbox-list navbox-even hlist" style="text-align:left;border-left-width:2px;border-left-style:solid;width:100%;padding:0px"><div style="padding:0em 0.25em">
<ul><li><a href="/enwiki/wiki/Congo_red" title="Congo red">Congo red</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/enwiki/wiki/Bacteria" title="Bacteria">Bacteria</a></th><td class="navbox-list navbox-odd hlist" style="text-align:left;border-left-width:2px;border-left-style:solid;width:100%;padding:0px"><div style="padding:0em 0.25em">
<ul><li><a class="mw-selflink selflink">Gram stain</a>
<ul><li><a href="/enwiki/wiki/Methyl_violet" title="Methyl violet">Methyl violet</a>/<a href="/enwiki/wiki/Crystal_violet" title="Crystal violet">Gentian violet</a></li>
<li><a href="/enwiki/wiki/Safranin" title="Safranin">Safranin</a></li></ul></li>
<li><a href="/enwiki/wiki/Ziehl%E2%80%93Neelsen_stain" title="Ziehl–Neelsen stain">Ziehl–Neelsen stain/acid-fast</a>
<ul><li><a href="/enwiki/wiki/Carbol_fuchsin" title="Carbol fuchsin">Carbol fuchsin</a>/<a href="/enwiki/wiki/Fuchsine" title="Fuchsine">Fuchsine</a></li>
<li><a href="/enwiki/wiki/Methylene_blue" title="Methylene blue">Methylene blue</a></li></ul></li>
<li><a href="/enwiki/wiki/Auramine%E2%80%93rhodamine_stain" title="Auramine–rhodamine stain">Auramine–rhodamine stain</a>
<ul><li><a href="/enwiki/wiki/Auramine_O" title="Auramine O">Auramine O</a></li>
<li><a href="/enwiki/wiki/Rhodamine_B" title="Rhodamine B">Rhodamine B</a></li></ul></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/enwiki/wiki/Connective_tissue" title="Connective tissue">Connective tissue</a></th><td class="navbox-list navbox-even hlist" style="text-align:left;border-left-width:2px;border-left-style:solid;width:100%;padding:0px"><div style="padding:0em 0.25em">
<ul><li><a href="/enwiki/wiki/Trichrome_stain" class="mw-redirect" title="Trichrome stain">trichrome stain</a>: <a href="/enwiki/wiki/Masson%27s_trichrome_stain" title="Masson's trichrome stain">Masson's trichrome stain</a>/<a href="/enwiki/wiki/Lillie%27s_trichrome" title="Lillie's trichrome">Lillie's trichrome</a>
<ul><li><a href="/enwiki/wiki/Light_Green_SF_yellowish" class="mw-redirect" title="Light Green SF yellowish">Light Green SF yellowish</a></li>
<li><a href="/enwiki/wiki/Biebrich_scarlet" title="Biebrich scarlet">Biebrich scarlet</a></li>
<li><a href="/enwiki/wiki/Phosphomolybdic_acid" title="Phosphomolybdic acid">Phosphomolybdic acid</a></li>
<li><a href="/enwiki/wiki/Fast_Green_FCF" title="Fast Green FCF">Fast Green FCF</a></li></ul></li></ul>
<ul><li><a href="/enwiki/wiki/Van_Gieson%27s_stain" title="Van Gieson's stain">Van Gieson's stain</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list navbox-odd hlist" style="text-align:left;border-left-width:2px;border-left-style:solid;width:100%;padding:0px"><div style="padding:0em 0.25em">
<ul><li><a href="/enwiki/wiki/Alcian_blue_stain" title="Alcian blue stain">Alcian blue stain</a></li>
<li><a href="/enwiki/wiki/Cyanine" title="Cyanine">Cyanine</a></li>
<li><a href="/enwiki/wiki/Jaswant_Singh%E2%80%93Bhattacharji_(JSB)_stain" class="mw-redirect" title="Jaswant Singh–Bhattacharji (JSB) stain">Jaswant Singh–Bhattacharji (JSB) stain</a></li>
<li><a href="/enwiki/wiki/H%26E_stain" title="H&E stain">H&E stain</a>
<ul><li><a href="/enwiki/wiki/Haematoxylin" title="Haematoxylin">Haematoxylin</a></li>
<li><a href="/enwiki/wiki/Eosin_Y" title="Eosin Y">Eosin Y</a></li></ul></li>
<li><a href="/enwiki/wiki/Janus_Green_B" title="Janus Green B">Janus Green B</a></li>
<li><a href="/enwiki/wiki/Giemsa_stain" title="Giemsa stain">Giemsa stain</a></li>
<li><a href="/enwiki/wiki/G%C3%B6m%C3%B6ri_trichrome_stain" title="Gömöri trichrome stain">Gömöri trichrome stain</a></li>
<li><a href="/enwiki/wiki/Luxol_fast_blue_stain" title="Luxol fast blue stain">Luxol fast blue stain</a></li>
<li><a href="/enwiki/wiki/Methyl_blue" title="Methyl blue">Methyl blue</a></li>
<li><a href="/enwiki/wiki/Movat%27s_stain" title="Movat's stain">Movat's stain</a></li>
<li><a href="/enwiki/wiki/Neutral_red" title="Neutral red">Neutral red</a></li>
<li><a href="/enwiki/wiki/Silver_stain" class="mw-redirect" title="Silver stain">Silver stain</a>
<ul><li><a href="/enwiki/wiki/Bielschowsky_stain" title="Bielschowsky stain">Bielschowsky stain</a></li>
<li><a href="/enwiki/wiki/Grocott%27s_methenamine_silver_stain" title="Grocott's methenamine silver stain">Grocott's methenamine silver stain</a></li>
<li><a href="/enwiki/wiki/Warthin%E2%80%93Starry_stain" title="Warthin–Starry stain">Warthin–Starry stain</a></li></ul></li>
<li><a href="/enwiki/wiki/Wright%27s_stain" title="Wright's stain">Wright's stain</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Tissue stainability</th><td class="navbox-list navbox-even hlist" style="text-align:left;border-left-width:2px;border-left-style:solid;width:100%;padding:0px"><div style="padding:0em 0.25em">
<ul><li><a href="/enwiki/wiki/Acidophile_(histology)" title="Acidophile (histology)">Acidophilic</a></li>
<li><a href="/enwiki/wiki/Basophilic" title="Basophilic">Basophilic</a></li>
<li><a href="/enwiki/wiki/Chromophobe" class="mw-redirect" title="Chromophobe">Chromophobic</a></li></ul>
</div></td></tr></tbody></table></div>
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