Clostridium perfringens

Clostridium perfringens
	Photomicrograph of gram-positive Clostridium perfringens bacilli.
Scientific classification
Kingdom:	Bacteria
Division:	Firmicutes
Class:	Clostridia
Order:	Clostridiales
Family:	Clostridiaceae
Genus:	Clostridium
Species:	perfringens
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

Clostridium 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, diarrhea, and sometimes nausea.

The action of C. perfringens on dead bodies is known to mortuary workers as tissue gas and can be halted only 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 74 °C) 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, 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 among 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. Gas production forms bubbles of gas in muscle (crepitus) and smell in decomposing tissue.
After rapid and destructive local spread (which can take hours), systemic spread of bacteria and bacterial toxins may result in death. This is a problem in major trauma and in military contexts.
Gram-positive spore can form anaerobic bacilli
It is a 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 anaerobic dead tissue or dirt. Produces cytotoxin that kills cells.
Traumatic wounds should be cleaned. Wounds that cannot be cleaned should not be stitched shut.
Spores can withstand boiling water. Autoclaving is necessary to ensure sterility.
Penicillin prophylaxis kills clostridia, and is thus useful for dirty wounds and lower leg amputations
If detected on clinical grounds, should not wait for lab results
If adrenalin used for injection is contaminated with spores, catastrophic reactions can result.
Prompt and adequate surgical attention is of paramount importance
Grows readily on blood agar plate in anaerobic conditions and often produces a zone of hemolysis
Growth in food can produce toxins causing acute, self-limiting diarrhea
High infectious dose is 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 identify strains that produce α-toxin, a diffusible lecithinase that 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. {{cite book}}: Explicit use of et al. in: |author= (help)

External links

Pathema-Clostridium Resource

[Sherris-1] 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)

[Barron-2] 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.

[O.T.M-3] 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).

[M.D.T-4] Murray; et al. (2009). Medical Microbiology (6th ed.). Mosby Elsevier. ISBN 978-0-323-05470-6. {{cite book}}: Explicit use of et al. in: |author= (help)

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