NAME: Clostridium spp. (excluding C. botulinum, C. difficile, C. perfingens, C. tetani)
SYNONYM OR CROSS REFERENCE: Common Clostridium pathogens include: Clostridium novyi Footnote 1, Footnote 2, C. septicum, C. sordellii, C. baratii, C. carnis, C. fallax, C. haemolyticum, C. histolyticum, C. limosum, C. bifermentans, C. clostridioforme, C. ramosum, C. sporogenes, C. tertium Footnote 3, C. innocum, C. paraputificum, C. subterminale, clostridial bacteremia Footnote 4, clostridial myonecrosis Footnote 5.
CHARACTERISTICS: Clostridium is a genus of gram-positive, spore-forming bacteria belonging to the family Clostridiaceae. Vegetative cells are rod shaped and arranged in pairs or short chains. The majority of species are obligate anaerobes; however, some species can grow under aerobic conditions or are aerotolerant. There are close to 200 species of Clostridium, with only a few species being pathogenic to humans. Several species produce toxins Footnote 1, Footnote 3.
PATHOGENICITY/TOXICITY: Pathogenic species are not invasive; however, certain strains of Clostridium produce toxins that cause symptoms and lesions associated with infection, such as tissue necrosis (C. novyi, C. septicum, S. sordellii) or botulism (C. baratii) Footnote 6. Unique strains of C. baratii and C. butyricum can, in addition to C. botulinum and C. argentinense (formerly C. botulinum type G) produce botulinum neurotoxin Footnote 3.
Illnesses primarily associated with Clostridium spp. are:
Clostridial bacteremia: Symptoms can vary greatly but will typically include fever, chills, and leukocytosis Footnote 4. The fatality rate ranges from 25-50% Footnote 2. Many Clostridium spp. can be associated with anaerobic bacteremia including C. septicum, C. ramosum, C. clostridioforme, or C. tertium Footnote 2, Footnote 7.
Clostridial Myonecrosis (Gas Gangrene): A rare but extremely fatal disease that results from the infection of muscle tissue by exotoxin producing Clostridium bacteria Footnote 5. Typical symptoms include severe pain in affected area, fever and tachycardia. Skin discoloration, appearance of haemorrhagic bullae, and subcutaneous gas appear in the late stages of infection Footnote 8. The most common cause of clostridial myonecrosis is C. perfringens Footnote 9. Approximately 70% of clostridial myonecrosis cases result from traumatic injury, and of these, about 80% are due to C. perfringensFootnote 10. Several other Clostridium spp. have been associated with cases of clostridial myonecrosis, including C. septicum, C. novyi, C. histolyticum, C. bifermentans, C. tertium, C. fallax, and C. sordellii Footnote 1, Footnote 3, Footnote 9, Footnote 10.
Necrotizing Enterocolitis (NEC): NEC is marked by ischemic necrosis of the intestinal mucosa, and is the most common gastrointestinal emergency in infants (1 to 3 cases per 1,000 live births) Footnote 4, Footnote 11. The etiology of NEC is not understood, although bacterial colonization of the gut is believed to play a role Footnote 11. Clostridium spp. have been particularly associated with more severe cases of NEC Footnote 4, Footnote 11.
Clostridium sordellii Toxic Shock Syndrome (CSTS): C. sordellii is one of the causes of toxic shock syndrome associated with gynaecological procedures, childbirth, and abortion Footnote 12. CSTS is marked by the rapid onset of severe illness with shock (edema, effusion, profound leukocytosis and hemoconcentration, followed by shock and multiorgan failure), and often occurs in previously healthy persons. The incidence of CSTS is not well characterized.
EPIDEMIOLOGY: Clostridium spp. occur worldwide and are widespread in the environment; commonly found in soil, feces, sewage, and marine sediments Footnote 3. Clostridial bacteremia and myonecrosis are relatively rare; people with underlying medical conditions and the elderly have an increased risk of developing infections Footnote 2, Footnote 3, Footnote 7, Footnote 13. Outbreaks of clostridial myonecrosis have been reported among injection drug users Footnote 14, Footnote 15.
INFECTIOUS DOSE: Unknown.
MODE OF TRANSMISSION: Contamination of wound sites and breaches in gastrointestinal tract; spontaneous cases can also occur Footnote 8.
INCUBATION PERIOD: 6 hours to 3 days for clostridial myonecrosis Footnote 5.
COMMUNICABILITY: Not directly transmitted from person-to-person.
ZOONOSIS: No, there is no evidence that Clostridium spp. can be transmitted directly from animals to humans Footnote 16.
DRUG SUSCEPTIBILITY/RESISTANCE: Antibiotic susceptibility for Clostridium spp. can vary Footnote 3, Footnote 4; however, most species are susceptible to penicillin, clindamycin, chloramphenicol, piperacillin, metronidazole, imipenem, and combinations of b-lactams with b-lactamase inhibitors Footnote 3, Footnote 9, Footnote 12.
SUSCEPTIBILITY/RESISTANCE TO DISINFECTANTS: Spores are resistant to most disinfectants and, when susceptible, they require longer contact time Footnote 17-Footnote 19. Clostridium spores are resistant to ethyl and propyl alcohols Footnote 17. Spores of Clostridium spp. can be killed by high level disinfectants such as 2% aqueous glutaraldehyde within 3 hours, 8% formaldehyde, 20 ppm sodium hypochlorite Footnote 17, Footnote 19.
PHYSICAL INACTIVATION: Spores of the genus Clostridium are generally heat resistant Footnote 18, Footnote 20 and can withstand temperature of 116 °C for 3 hours, whereas there vegetative cells can be rapidly killed by temperatures of only 55 to 65 °C Footnote 20. Spore can, however, be killed by saturated steam under pressure of 15 pounds at 121 °C Footnote 21. Spores can also be killed by moist heat at 100 °C in 29 minutes when suspended in pH 7 and in 11 minutes when suspended in pH 10.2 or 4.1 Footnote 20.
SURVIVAL OUTSIDE HOST: Clostridium spp. are able to form resistant endospores which are ubiquitous in the environment Footnote 3.
SURVEILLANCE: Monitor for symptoms. Can be diagnosed based on clinical presentation and direct isolation of bacteria from samples Footnote 3, Footnote 13. Puncture wounds should be observed for abscess formations and gas in tissue; conditions which require rapid clinical diagnosis if present Footnote 3.
PROPHYLAXIS: Cleaning any wound sites with an antiseptic; antibiotic may be prescribed Footnote 1.
LABORATORY-ACQUIRED INFECTIONS: At least six cases of laboratory-acquired infections with Clostridium spp. have been reported up to 1976 Footnote 22.
PRIMARY HAZARDS: Parenteral inoculation.
SPECIAL HAZARDS: None.
RISK GROUP CLASSIFICATION: Risk Group 2. This risk group applies to the Clostridium genus as a whole, and may not apply to every species within the genus.
CONTAINMENT REQUIREMENTS: Containment Level 2 facilities, equipment, and operational practices for all work involving infected or potentially infected material Footnote 24. These containment requirements apply to the Clostridium genus as a whole, and may not apply to each species within the genus.
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 24.
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 24.
SPILLS: Allow aerosols to settle and, wearing protective clothing, gently cover spill with paper towels and apply an appropriate disinfectant, starting at the perimeter and working towards the centre. Allow sufficient contact time before clean up Footnote 24.
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 Footnote 24.
STORAGE: The infectious agent should be stored in leak-proof containers that are appropriately labelled Footnote 24.
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