Clostridium difficile-associated disease in horses

Summary

In the last 20 years, C. difficile has become accepted as an enteric pathogen in horses, particularly in Europe and the USA but not universally in Australia. Faecal samples from at least 200 horses of different breeds (although has been shown not to be important), ages and sex will be investigated. Specimens will be collected from horses with diarrhoea (>100) and without (>100). Data will be collected on antibiotic exposure and other potential risk factors. In addition, samples will be collected from the different environments in which horses are found, such as stables and paddocks, to ascertain the extent of environmental contamination, and its relation to infection. Environmental samples will also be collected from veterinary clinics that treat horses, as previous work has shown that veterinary clinics can become grossly contaminated with C. difficile, potentially posing a risk to animals and veterinarians. Specimens will be processed using published methods that we have developed over 25 years. These include culture on cycloserinecefoxitinfructose agar anaerobically, and the use of an enrichment broth. Faecal cytotoxin will be detected in Vero cell monolayers. Putative isolates will be identified by speciesspecific PCR that will also identify the presence of toxin A, B and binary toxin genes. Antimicrobial susceptibility patterns will be determined by agar dilution and Estrip, and the relationship between C. difficile diarrhoea and antibiotic exposure assessed.

Program

Thoroughbred Horses

Research Organisation

University of Western Australia

Objective Summary

The objectives of this project are to determine: a) the prevalence of Clostridium difficile in the gastrointestinal tract of horses in Australia in relation to age, occurrence of diarrhoea and history of exposure to antibiotics; b) the occurrence of C. difficile in the equine environment; and c) production of toxins by and the antibiotic susceptibility patterns of any strains isolated. This project addresses one of the industry’s key longterm strategies: disease prevention, diagnosis and treatment.