Abstract

Clostridium difficile is a gram-positive, anaerobic, spore-forming bacterium commonly found in the gastrointestinal tract of humans, domestic animals, and wildlife species. In the last 10 years, 15 cases of segmental to diffuse fibrinohemorrhagic enterocolitis suggestive of C. difficile infection based on bacterial isolation, ELISA analysis for toxins A and B, and pathology findings were reported in harbor seals (Phoca vitulina) undergoing rehabilitation at the Vancouver Aquarium's Marine Mammal Rescue Centre (Raverty et al.). Most animals died acutely of no overt pre-monitory signs. In 2009, the prevalence of C. difficile was investigated in nearly 100 harbor seals at the Marine Mammal Rescue Centre through fecal samples collected on admission, post-antibiotic treatment, and pre-release or post-mortem (pending the rehabilitative outcome). All samples were collected fresh, stored frozen, and analyzed by the British Columbia Provincial Animal Health Centre for bacterial culture and ELISA detection for C. difficile toxins A and B. The study encompassed a total of 205 fresh fecal samples and 29 post-mortem specimens. Of the 86 pups sampled in the study, positive ELISA results were as follows: 12/73 positive on admission, 10/48 following one round of antibiotic treatment, 0/12 following two rounds of antibiotic treatment, 0/4 following three rounds of antibiotic treatment, and 1/67 on pre-release examination. (The post-mortem results were incomplete at the time of abstract submission). 47 pups were sampled both on admit and pre-release exam and 24 of those pups received a minimum of 1 round of antibiotic treatment. Released pups that received antimicrobial therapy had an ELISA positive rate of 4/24. 18 pups were sampled on admit and post-mortem examination, 5 of which received a minimum of 1 round of antibiotic treatment. Deceased pups which received antimicrobial therapy had an ELISA positive rate of 4/5.The results from this study provide some insights into: 1) the prevalence of C. difficile toxin production in young harbor seals upon admit to a rehabilitation center, 2) the affects of antibiotic treatment in development of C. difficile infection, 3) the outcome of seals treated in a rehabilitation setting to evaluate nosocomial infections and asymptomatic carriers, and 4) the role of C. difficile infection in harbor seal mortality. Currently the exact pathogenesis of C. difficile causing gastrointestinal disease is unknown in harbor seals. Therefore, the results from this pilot study will help direct pinniped treatment protocols to minimize C. difficile disease.

Acknowledgments

Lindsaye Akhurst, staff, students, and volunteers of the Vancouver Aquarium's Marine Mammal Rescue, Jaime Osei-Appiah and Roberta Yemen of the British Columbia Provincial Animal Health Centre, Drs. Vilma Yuzbasiyan-Gurkan and Scott Fitzgerald of Michigan State University, and Michigan State University College of Veterinary Medicine. Funding for the project was provided by the Morris Animal Foundation (Veterinary Student Scholars Program), British Columbia Provincial Animal Health Centre, Vancouver Aquarium, and Michigan State University.

Reference

1.  Raverty S, Carlsen K, Whitton E, Byrne S. Hemorrhagic enteritis associated with Clostridium difficile toxin A and B in harbor seals (Phoca vitulina) in Washington state and British Columbia. International Association of Aquatic Animal Medicine, Galveston, Texas, April 2-6, 2004.