Clostridia are anaerobic, but aerotolerant, rod shaped, gram-positive bacteria.4,5 They are harbored in the gastrointestinal tract of many animals, including humans where the organism is also found in the female genital tract.4,5 Both Clostridium perfringens and C. difficile elaborate toxins that produce diarrheal diseases and both form spores that are stable in the environment.1,3,4,12
Clostridium perfringens type A causes enterotoxicosis in mink (Mustela vison), dogs, and cheetahs (Acinonyx jubatus jubatus) as well as food poisoning in humans.2,4,6,7,12 The cue for toxin production is unclear but may be different in food poisoning versus naturally occurring diarrhea.7 Clostridium perfringens type A may be spread via spores in food, ingestion of spores from the environment, or fecal-oral transmission.12
Clostridium difficile toxin causes enterocolitis, characterized, in its most severe form, as pseudomembranous colitis as seen in hamsters (Cricetus spp.), rabbits (Oryctolagus spp.), guinea pigs (Cavia porcellus), Kodiak bears (Ursus arctos middendorffi), cotton top tamarins (Saguinus oedipus) and humans subsequent to antibiotic administration.1,4,9,11 Clinical signs in humans range from mild self-limiting diarrhea to life-threatening pseudomembranous colitis.1 The organism can be isolated from the stools of 3% of healthy human adults who have not previously been treated with antibiotics.1 In one human study, antibiotic treatment increased the frequency of asymptomatic carriers to 48%.3 In human infants, C. difficile and its toxins are commonly present in the gastrointestinal system, but do not cause disease. It is hypothesized that neonate intestinal epithelium does not yet have a toxin receptor.8 Clostridium difficile causes naturally occurring enterocolitis in swine (Sus scrota) and foals (Equus caballus) suggesting that there are circumstances other than antibiotic depression of normal flora which may create conditions allowing C. difficile to proliferate and subsequently produce toxin.4 There are many factors which contribute to the pathogenicity of C. difficile, of which the most important, and most widely studied is toxin production.3
A cross-sectional survey was performed to determine the prevalence of fecal C. perfringens and C. difficile toxins in healthy, asymptomatic, non-human primates at the Wildlife Conservation Park/Bronx Zoo. This study was conducted after several clinically ill callitrichids were suspected of having clostridial disease. These animals developed signs of wasting disease, with or without diarrhea, and did not respond to conventional therapy of nutritional supplementation, fluids, and broad-spectrum antibiotics.10 Fecal samples from these animals were positive for C. perfringens and/or C. difficile toxins. The animals demonstrated weight gains and improved attitudes within 3 days of treatment with metronidazole benzoate (Mortar and Pestle Pharmacy, Des Moines, IA) (25–30 mg/kg divided BID) and tylosin tartate (Tylan, Elanco Animal Health, Indianapolis, IN) (5 mg/kg BID).
Individuals from one building with 19 enclosures containing approximately 75 individuals of 15 primate species (callitrichids, callimicos, and cebids) were evaluated. Composite fecal samples from each enclosure were submitted for anaerobic bacterial culture, an enzyme linked immunoassay for detection of C. difficile toxin, and a reverse passive latex agglutination test for C. perfringens toxin.
Clostridium difficile and C. perfringens toxins were detected together in feces from 12/19 (63.2%) enclosures, C. difficile toxin was detected alone in 5/19 (26.3%), and no toxins were detected in 2/19 (10.5%) enclosures. Clostridium perfringens was cultured from feces in 4/19 (21%) enclosures and C. difficile was not isolated from any enclosure.
Eleven of 19 (57.9%) enclosures had animals born within 1 year preceding the survey and of these, four (36.4%) had animals born within 2 months of the start of the survey. At the time of sampling none of the animals were being treated with antibiotics, although animals in five enclosures (26.3%) had been treated with antibiotics within the preceding year and three of these (60%) had been treated within the previous month. Surveyed animals were on a rotating bimonthly anthelmintic and antiprotozoal program during the sampling period.
The results of this survey demonstrated that most of the enclosures surveyed were positive for one or both toxins, although the animals contained in them were asymptomatic. There was no correlation between the presence of young animals in the group and the detection of toxins or between a history of recent antibiotic treatment and positive test results. Finally, culture results correlated poorly with the presence of toxin. One enclosure from which C. perfringens was cultured was toxin negative and nine enclosures were C. perfringens culture negative and C. perfringens toxin positive. Bacterial culture is not specific for type A toxin producing C. perfringens and this may partially explain the poor correlation between culture and toxin results. C. difficile culture is technically difficult and may yield false negative results (P. McDonnough, personal communication). In both cases, the toxin test is more sensitive than culture (P. McDonnough, personal communication). Based on these findings, it was not possible to determine the role of C. perfringens and C. difficile toxins in diarrheal or wasting diseases because animals were positive for either or both toxins without clinical illness. However, several cases which stimulated this broader survey demonstrated that animals may respond to treatment for clostridial disease when conventional therapy fails. This evidence and the results of this study, indicate that more research on this topic is needed to understand the significance of positive clostridial toxin screen in primates.
The authors thank Dr. Patrick McDonnough for his support, guidance, and assistance with interpretation of results.
1. Brian MJ, Cleary TG, Kreth HW. Antimicrobial agent-associated pseudomembranous colitis. In: Eichenwald EF, Stroder J, Ginsburg SM, eds. Pediatric Therapy. St. Louis, MO: Mosby; 1993:770–772.
2. Citino SB. Diagnosis of Clostridium perfringens enterotoxicosis in a collection of cheetahs (Acinonyx jubatus jubatus). In: Proceedings of the American Association of Zoological Veterinarians. 1994:347–349.
3. Dodson AP, Borriello SP. Clostridium difficile infection of the gut. J Clin Pathol. 1996;49:529–532.
4. Timoney JF, Gillespie JH, Scott FW, Barlough JE, eds. Hagan And Bruner’s Microbiology and Infectious Diseases of Domestic Animals. Ithaca, NY: Cornell University Press; 1988:214–240.
5. Kasper DL, Zaleznik DF. Gas Gangrene and other clostridial infections. In: Isselbacher KJ, Braunwald E, Wilson JD, Martin JB, Fauci AS, Kasper DL, eds. Harrison’s Principles of Internal Medicine. New York, NY: McGraw-Hill, Inc.; 1994:636–640.
6. Kruth SA, Prescott JF, Welch MK, Brodsky MH. Nosocomial diarrhea associated with enterotoxigenic Clostridium perfringens infections in dogs. J Am Vet Med Assoc. 1989;195:331–334.
7. McClane BA. An overview of Clostridium perfringens enterotoxin. Toxicon. 1996;34:1335–1343.
8. Behrman RE, Kliegman RM, eds. Nelson Textbook of Pediatrics. Philadelphia, PA: W.B. Saunders; 819–820.
9. Orchard JL, Fekety R, Smith JR. Antibiotic associated colitis due to Clostridium difficile in a Kodiak bear. Am J Vet Res. 1983;44:1547–1548.
10. Potkay S. Diseases of the Callitrichidae: a review. J Med Primatol. 1992;21:189–236.
11. Rolland RM, Chalifoux LV, Snook SS, Ausman LM, Johnson LD. Five spontaneous deaths associated with Clostridium difficile in a colony of cotton-top tamarins (Saguinus oedipus). Lab Anim Sci. 1997;47:472–476.
12. Wada A, Masuda Y, Fukayama M, Hatakeyama T, Yanagawa Y, Watanabe H, Inamatsu T. Nosocomial diarrhoea in the elderly due to enterotoxigenic Clostridium perfringens. Microbiol Immunol. 1996;40:767–771.