Clostridium perfringens
| Clostridium perfringens | |
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| Photomicrograph of gram-positive Clostridium perfringens bacilli. | |
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| Species: | perfringens
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| Binomial name | |
| Clostridium perfringens Veillon & Zuber 1898
Hauduroy et al. 1937 | |
Clostridium perfringens (formerly known as "C. welchii") is a Gram-positive, rod-shaped, anaerobic, spore-forming bacterium of the genus Clostridium.[1] C. perfringens is ubiquitous in nature and can be found as a normal component of decaying vegetation, marine sediment, the intestinal tract of humans and other vertebrates, insects, and soil.
Infection characteristics
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C. perfringens is commonly encountered in infections as a benign component of the normal flora.[2] In this case, its role in disease is minor.
Infections due to C. perfringens show evidence of tissue necrosis, bacteremia, emphysematous cholecystitis, and gas gangrene, which is also known as clostridial myonecrosis. The toxin involved in gas gangrene is known as α-toxin, which inserts into the plasma membrane of cells, producing gaps in the membrane that disrupt normal cellular function.[3]
After ingestion bacteria multiply and lead to colic, diarrhoea and sometimes nausea.
The action of C. perfringens on dead bodies is known to mortuary workers as tissue gas and can only be halted by embalming.
Food poisoning
In the United Kingdom and United States C. perfringens bacteria are the third most common cause of food-borne illness, with poorly prepared meat and poultry the main culprits in harboring the bacterium.[3] The Clostridium perfringens enterotoxin (CPE) mediating the disease is heat-labile (dies at 74C) and can be detected in contaminated food, if not heated properly, and feces .[4]
Incubation time is between 6 and 24 (commonly 10-12) hours after ingestion of contaminated food. Often times meat is well prepared but too far in advance of consumption. Since C. perfringens forms spores that can withstand cooking temperatures, if let stand for long enough germination ensues and infective bacterial colonies develop. Symptoms typically include abdominal cramping and diarrhea - vomiting and fever are unusual. The whole course usually resolves within 24 hours. Very rare, fatal cases of clostridial necrotizing enteritis (also known as Pig-Bel) have been known to involve "Type C" strains of the organism, which produce a potently ulcerative β-toxin. This strain is most frequently encountered in Papua New Guinea.
It is likely that many cases of C. perfringens food poisoning remain subclinical, as antibodies to the toxin are common amongst the population. This has led to the conclusion that most of the population has experienced food poisoning due to C. perfringens.[3]
Gas gangrene
Clostridium perfringens is the most common bacterial agent for Gas gangrene. • Gangrene is necrosis and putrefaction of tissues—due to gas production feel bubbles of gas in muscle (crepitus) and smell in decomposing tissue • Formerly important complication of surgery—complicate lower limb amputation as normally present in small no. in colon and perineum • After rapid and destructive local spread (hours) systemic spread of bacteria and bacterial toxins may result in death—problem in major trauma and military • Gram +ve spore forming anerobic bacilli • Saprophyte meaning it occurs in soil, H2O, decomposing plant, human and animal feces • Under appropriate conditions, spores can reactivate into a vegetative cell • Can grow in anerobic dead tissue or dirt—produces cytotoxin that kills cells—anerobic • Traumatic wounds should be cleaned—if can’t clean don’t stitch it • Spores can withstand boiling water—to ensure sterility autoclaving necessary • Penicillin(kills clostridia) prophylaxis for dirty wounds and lower leg amputations • Surgical emergency as can’t sure or control gas gangrene—penicillin as suuportive • If detected on clinical grounds, should not wait for lab results • If adrenalin used for injection with spores—reaction catastrophic • Prompt and adequate surgical attention is paramount importance • Grow readily on blood agar plate in anaerobic conditions and often produce a zone of hemolysis • Growing in food can produce toxins causing acute, self-limiting diarrhea • High infectious dose required—carrier state persists for several days
Colony characteristics
On blood agar plates, C. perfringens grown anaerobically produces β-haemolytic, flat, spreading, rough, translucent colonies with irregular margins. A Nagler agar plate, containing 5-10% egg yolk, is used to presumptively identify strains which produce α-toxin, a diffusible lecithinase which interacts with the lipids in egg yolk to produce a characteristic precipitate around the colonies. One half of the plate is inoculated with antitoxin to act as a control in the identification.
References
- ^ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN 0-8385-8529-9.
{{cite book}}:|author=has generic name (help)CS1 maint: multiple names: authors list (link) - ^ Wells CL, Wilkins TD (1996). Clostridia: Sporeforming Anaerobic Bacilli. In: Barron's Medical Microbiology (Barron S et al., eds.) (4th ed.). Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1.
- ^ a b c Warrell; et al. (2003). Oxford Textbook of Medicine (4th ed.). Oxford University Press. ISBN 0-19-262922-0.
{{cite book}}: Explicit use of et al. in:|author=(help) Cite error: The named reference "O.T.M" was defined multiple times with different content (see the help page). - ^ Murray; et al. (2009). Medical Microbiology (6th ed.). Mosby Elsevier. ISBN 978-0-323-05470-6.
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