Leptospira
| Leptospira | |
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| Scanning electron micrograph of Leptospira interrogans. | |
| Scientific classification | |
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| Phylum: | |
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| Genus: | Leptospira Noguchi 1917
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| Species | |
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L. alexanderi | |
Leptospira is a genus of spirochaete bacteria, including a small number of pathogenic and saprophytic microorganisms.[1] The first Leptospira to be described was L. interrogans in 1907 (as Spirochaeta interrogans) was isolated from kidney tissue slices of a Leptospirosis victim. For quite some time, the genus only had two members - the pathogenic L. interrogans and saprophytic L. biflexia.
Nomenclature
Leptospira is placed in the family Leptospiraceae, together with the genus Leptonema. The IUMS (2002) confirmed nomenclature for Leptospira is as follows:
- Genus species serovar Serovar_name
- Genus and species italicised, serovar name in plain text, genus and serovar capitalised and species lowercase.
- Examples include:
- Leptospira interrogans serovar Ballum
- Leptospira biflexa serovar Codice
Description
The Leptospira are an extremaly varied (over 200 serovars known) group of helix-shaped motile gram-negative bacteria; if straightened, they'd measure 6-20 μm long and 0.1-0.15μm in diameter. The number of curls depends on the straightened length and varius up to as much as 20.[2]
The bacteria have a number of freedom degrees; when ready to proliferate via binary fission, the bacterium noticeably bends in the place of the future split.
Pathogenic leptospira have hook-like ends and extensively use axial flagella (one on each end) for penetration into host organism tissue; human infection may occur through even slightly damaged skin, mucouse membranes or eyes.
Leptospira, both pathogenic and saprophytic, can occupy diverse environments, habitats and life cycles; it generally recognized these bacteria are virtually ubiquitous in terms of geographic distribution (present everywhere except Antarctica).[3]
Most of Leptospira, however, are hydrophilic - high humidity and neutral (6.9-7.4) pH are essential for their survival in the environment, with stagnant water reservoirs - bogs, shallow lakes, ponds, puddles, etc - being natural placeholder for the bacteria. Proliferation rate is typically slow; growth in an artificial nutrient environment (for L. interrogans, one typicaly contains human blood serum) becomes noticeable in around 5-7 days. Parasitic species' optimal growth temperature is 28-32°C, while saprophytic one can grow at as low as 13°C.
Due to high variance of the pathogens, Leptospira-caused diseases leave immunity only to a particular serovar that actually caused the infection. This circumstance prevents creation of effective vaccines against leptospirosis.
See also
References
- ^ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. ISBN 0838585299.
{{cite book}}:|author=has generic name (help);|edition=has extra text (help)CS1 maint: multiple names: authors list (link) - ^ Johnson RC (1996). Leptospira. In: Barron's Medical Microbiology (Barron S et al, eds.) (4th ed. ed.). Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1.
{{cite book}}:|edition=has extra text (help) - ^ Madigan M; Martinko J (editors). (2005). Brock Biology of Microorganisms (11th ed. ed.). Prentice Hall. ISBN 0131443291.
{{cite book}}:|author=has generic name (help);|edition=has extra text (help)CS1 maint: multiple names: authors list (link)