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Laboratory Diagnosis of Clostridium perfringens
For Diarrheal Disease
- Laboratories diagnose C. perfringens food poisoning by detecting a type of bacterial toxin in feces or by tests to determine the number of bacteria in the feces.
- A count of at least 106 C. perfringens spores per gram of stool within 48 hours of when the illness began is required to diagnose infection.
For Other Infections
- Specimens consist of material from wounds, pus, and tissue.
- The presence of large gram-positive rods in Gram-stained smears suggests clostridia; spores are not regularly present.
- Material is inoculated into chopped meat–glucose medium and thioglycolate medium and onto blood agar plates incubated anaerobically.
- The growth from one of the media is transferred into the milk. A clot torn by gas in 24 hours is suggestive of C. perfringens.
- After pure cultures have been obtained by selecting colonies from anaerobically incubated blood plates, they are identified by biochemical reactions (various sugars in thioglycolate, action on milk), hemolysis, and colony morphology.
- Lecithinase activity is evaluated by the precipitate formed around colonies on egg yolk media.
- Final identification rests on toxin production and neutralization by specific antitoxin.
Note: C. perfringens rarely produces spores when cultured on agar in the laboratory.
- C. perfringens can be diagnosed by Nagler’s reaction, where the suspect organism is cultured on an egg yolk media plate.
- One side of the plate contains anti-alpha-toxin, while the other side does not.
- A streak of a suspect organism is placed through both sides.
- An area of turbidity will form around the side that does not have the anti-alpha-toxin, indicating uninhibited lecithinase activity.
Catalase: Negative, Spot indole: Positive, Lecithinase: Positive, Lipase: Negative, Litmus Milk: Stormy Fermentation, Reverse CAMP plate: Positive, Gas-Liquid Chromatography products: (Acetic, Butyric, and Lactic Acids).
- The most important aspect of treatment is prompt and extensive surgical debridement of the involved area and excision of all devitalized tissue, in which the organisms are prone to grow.
- Administration of antimicrobial drugs, particularly penicillin, is begun at the same time.
- Hyperbaric oxygen may be of help in the medical management of clostridial tissue infections. It is said to “detoxify” patients rapidly.
- Antitoxins are available against the toxins of C. perfringens usually in the form of concentrated immune globulins. Polyvalent antitoxin (containing antibodies to several toxins) has been used.
- Food poisoning caused by C. perfringens enterotoxin usually requires only symptomatic care.
- Oral rehydration or, in severe cases, intravenous fluids and electrolyte replacement can be used to prevent or treat dehydration.
- Antibiotics are not recommended.
Prevention of Infection
- The growth of C. perfringens spores can be prevented by most importantly cooking food, especially beef, and poultry, thoroughly, to the recommended temperatures.
- Leftover food should be refrigerated to a temperature below 40 °F (4 °C) within two hours of preparation.
- Large pots of food such as soup or stew with meats should be divided into small quantities and covered for refrigeration.
- Leftovers should be reheated to at least 165 °F (74 °C) before serving.
- A rule of thumb is that if the food tastes, smells, or looks different from what it is supposed to, then the food should be avoided. Even if it looks safe, a food that has been out for a long time can also be dangerous to eat.
- In case of tissue infections, early and adequate cleansing of contaminated wounds and surgical debridement, together with the administration of antimicrobial drugs directed against clostridia (eg, penicillin), are the best available preventive measures.
- Antitoxins should not be relied on. Although toxoids for active immunization have been prepared, they have not come into practical use.
- Murray, P. R., Rosenthal, K. S., & Pfaller, M. A. (2013). Medical microbiology. Philadelphia: Elsevier/Saunders.