NAME: Clostridium perfringens
CHARACTERISTICS: Clostridium perfringens, of the Clostridiaceae family, is non-motile, anaerobic, (few strains are aerotolerant), spore forming bacteria (subterminal spores) that are encapsulated in tissue smears Footnote 2, Footnote 5. Vegetative cells are rod shaped, pleomorphic, and occur in pairs or short chains Footnote 5. It is catalase and superoxide dismutase negative Footnote 5, and has 5 toxigenic types (A-E), of which A and C strains are pathogenic for humans. It produces many different toxins Footnote 1.Colonies with double zone of hemolysis are produced when cultured at 37oC on blood agar overnight Footnote 1.
PATHOGENICITY/TOXICITY: Clostridial Food Poisoning: Food poisoning can be caused by C. perfringens enterotoxin (CPE) produced by C. perfringens spores in the small intestine Footnote 5, which can germinate in foods such as meat and poultry Footnote 6. In the United States consumption of large amounts of C. perfringens is considered an important cause of watery diarrhea Footnote 6. Main symptoms of the disease are nausea, abdominal pain, and diarrhea Footnote 1. The disease is usually mild and self-limiting in healthy individuals, with symptoms resolving within 24 hours Footnote 1, Footnote 4, Footnote 5.
Clostridial Myonecrosis (Gas Gangrene): C. perfringens is the most common cause of clostridial myonecrosis Footnote 7. The disease involves breakdown of muscle tissue due to the action of potent exotoxins, alpha and theta, produced by the bacteria Footnote 5. It is manifested by severe pain, edema, tenderness and pallor, followed by discoloration and hemorrhagic bullae, and production of gas at the site of wound Footnote 1. Systemic manifestations of the disease include shock, renal failure, hypotension, bacteremia with intravascular hemolysis leading to coma and death Footnote 1, Footnote 5.
Clostridial Cellulitis: C. perfringens is the most common cause of clostridial cellulitis, which is often associated with local trauma or recent surgery Footnote 8, Footnote 9. Infection is less systemic than in clostridial myonecrosis, with localized infection and associated skin and soft tissue necrosis, but sparing of the fascia and deep muscles.
Enteritis Necrotican (pigbel): Enteritis necroticans is a life threatening infection involving ischemic necrosis of the jejunum Footnote 5. The often fatal disease is caused by C. perfringens type C Footnote 4, Footnote 10, and is marked by hemorrhagic, inflammatory, or ischemic necrosis of the jejunum. Most cases occur sporadically, during outbreatks, or in underdeveloped countries.
CNS manifestations of C. perfringens infection: CNS diseases due to C. perfringens infection are rare Footnote 3. The main manifestations of C. perfringens infection in CNS are meningitis and encephalitis. Clinical symptoms of the two diseases are similar and include tiredness, fever, headache, vomiting, hypersensitivity to light or noise, neck stiffness, or impaired consciousness and coma Footnote 3.
EPIDEMIOLOGY: Food poisoning: C. perfringens is one of the most common causes of food poisoning in United States and Canada Footnote 5. Contaminated meats contained in stews, soups and gravies are usually responsible for outbreaks in developed countries Footnote 1 and causes about 250,000 cases of food borne illness every year in USA Footnote 4. Deaths due to the disease are rare and occur mainly in elderly, debilitated, or individuals predisposed to the disease Footnote 4.
Gas Gangrene: C. perfringens is the most common cause of trauma associated gas gangrene with very high mortality rates Footnote 11. The World Health Organization reported that many injured people in the Schezuan earthquake in china in 2008 developed gas gangrene Footnote 12. Furthermore from April-August 2000, several drug users in Scotland developed clostridial infections (3 of which were due to C. perfringens) with a high mortality rate Footnote 13.
Enteritis Necroticans: It was first recognized as a frequent cause of death among children in New Guinea in the 1960s. It has also been reported to occur among malnourished adults or people with chronic diseases such as diabetes in USA, United Kingdom, Germany and other developed nations Footnote 4, Footnote 5.
INFECTIOUS DOSE: Unknown.
Food Poisoning: Ingestion of food containing 108 or more viable vegetative C. perfringens cells can result in food poisoning Footnote 5.
MODE OF TRANSMISSION: Food Poisoning: Food-borne illness acquired by ingestion of large number of C. perfringens vegetative cells present in the food Footnote 5, Footnote 14. Food sources are usually cooked meat, vegetables, fish or poultry dishes which have been stored at ambient temperatures for a long time after cooking.
Enteritis Necroticans: Ingestion of contaminated pork meat Footnote 5.
Gas Gangrene/ Anaerobic Cellulitis: Infection can occur through contamination of wounds (fractures, bullet wounds) with dirt or any foreign material contaminated with C. perfringens Footnote 1.
INCUBATION PERIOD: Food Poisoning: 8-24 hours Footnote 2.
Gas Gangrene: 1-4 days after the injury, but may also start within 10 hours Footnote 1.
COMMUNICABILITY: Not directly transmitted from person to person.
RESERVOIR: Soil, water, air, feces of healthy and infected individuals, dust, vegetation, gastrointestinal tract of humans and animals, and variety of dehydrated and processed foods Footnote 2, Footnote 5, Footnote 14, Footnote 15.
ZOONOSIS: C. perfringens type A food-borne disease and infections by C. perfringens type C can be transmitted from animals to humans Footnote 4.
DRUG RESISTANCE: Some strains resistant to clindamycin have been isolated Footnote 16.
SUSCEPTIBILITY TO DISINFECTANTS: Spores are resistant to most disinfectants and, when susceptible, they require longer contact time Footnote 17, Footnote 18. Clostridium spores are resistant to ethyl and propyl alcohols, chlorine dioxide Footnote 17, Footnote 19. Spores of clostridium species can be killed by high level disinfectants such as 2% aqueous glutaraldehyde within 3 hours, and 8% formaldehyde Footnote 17, Footnote 18.
PHYSICAL INACTIVATION: Spores are highly resistant to both heat, and gamma-irradiation. Enterotoxin is heat labile and can be inactivated by heat treatment at 60oC for 5 minutes Footnote 2, Footnote 4.Vegetative cells can be rapidly killed by dry heat at 160-170°C for 1-2 hours or moist heat at 121°C for 15 min- 30 min Footnote 20.
SURVIVAL OUTSIDE HOST: Spores can survive in soil, crevices, food, decaying vegetation, marine sediments, internal cavities and in the anaerobic conditions inside the meat rolls, animal carcasses, feces, dehydrated and cooked food Footnote 2, Footnote 3.
SURVEILLANCE: Diagnosis is based mainly on clinical symptoms Footnote 1.
Food borne illness: Diagnosis consists of: 1) culture and characterization of the bacteria including Gram-stain; 2) PCR amplification of the enterotoxin (cpe) gene, as toxin production is associated with its presence; and 4) detection of CPE in feces through toxin assay, cell culture assay, ELISA or RPLA (reverse-phase latex agglutination) Footnote 5.
Enteritis Necroticans: Diagnosis consists of direct Gram stain of specimens from symptomatic patients, and culture and characterization of the bacteria. Typing can be done using PCR assay for the cpa and cpb genes, which code for a- and b-toxins, respectively Footnote 5.
Gas gangrene/Anaerobic cellulitis: Diagnosis consists of direct Gram stain smear of the wound for the presence of short chains of large, fat gram positive rods with blunt ends from symptomatic patients Footnote 5.
Note: All diagnostic methods are not necessarily available in all countries.
FIRST AID/TREATMENT: Food poisoning: Self-limiting disease. Therapy in mainly supportive; bowel resection may be required for very severe cases Footnote 4.
Gas Gangrene: Treatment mainly involves excision of all devitalized tissue in conjunction with antibiotic therapy with a combination of penicillin and clindamycin or tetracycline, which appear most effective based on animal models Footnote 1, Footnote 3, Footnote 11, Footnote 21. In vitro, chloramphenicol, metronidazole, and several cephalosporins are active against C. perfringensFootnote 21. There have been a few reports of successful results using hyperbaric oxygenation in adjunctive therapy Footnote 3.
Anaerobic Cellulitis: Surgical debridement of the tissue and antibiotic therapy with penicillin or clindamycin. In case of drug resistance to clindamycin, second line antibacterial agents such as vancomycin can be used Footnote 16.
LABORATORY-ACQUIRED INFECTIONS: None have been reported to date.
SOURCE/SPECIMENS: Human feces, suspect food in a food borne illness, blood, bowel luminal contents or tissue from the involved bowel in case of enteritis necroticans, wound exudates Footnote 5.
PRIMARY HAZARDS: Accidental ingestion of the enterotoxin, direct contact of open wounds/site of injury with the pathogen, accidental parenteral inoculation of the toxin Footnote 5.
SPECIAL HAZARDS: None.
RISK GROUP CLASSIFICATION: Risk Group 2 Footnote 22. This risk group applies to the species as a whole, and may not apply to every strain.
CONTAINMENT REQUIREMENTS: Containment Level 2 facilities, equipment, and operational practices for work involving infectious or potentially infectious materials, animals, or cultures. These containment requirements apply to the species as a whole, and may not apply to each strain within the species.
PROTECTIVE CLOTHING: Lab coat. Gloves when direct skin contact with infected materials or animals is unavoidable. Eye protection must be used where there is a known or potential risk of exposure to splashes Footnote 23.
OTHER PRECAUTIONS: All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC). The use of needles, syringes, and other sharp objects should be strictly limited. Additional precautions should be considered with work involving animals or large scale activities Footnote 23.
SPILLS: Allow aerosols to settle, and wearing protective clothing, gently cover the spill with paper towels and apply an appropriate disinfectant, starting at the perimeter and then working towards the centre. Allow sufficient time contact time before clean up Footnote 23.
DISPOSAL: Decontaminate all wastes that contain or have come in contact with the infectious organism before disposing by autoclave, chemical disinfection, gamma irradiation, or incineration.
STORAGE: The infectious agent should be stored in leak-proof containers that are appropriately labelled.Footnote 23.
UPDATED: December 2011
PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada
Although the information, opinions and recommendations contained in this Pathogen Safety Data sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.
Public Health Agency of Canada, 2011