Clostridium difficile in horses in Australia–a preliminary study.

This research conducted from 2007 to 2009 investigates the presence of Clostridium difficile, a bacterium often associated with diarrhea and colitis, in horses in Australia. The study found that it was isolated from 23% of horses with diarrhea but none of the healthy adult horses. The bacteria found were analyzed for different toxin profiles and varied ribotypes, all of which were susceptible to common antibiotics.

Investigation Method and Findings

• Over 24 months, 174 horse fecal samples were collected and examined for the presence of Clostridium difficile bacteria. The majority of these samples were obtained from horses in Western Australia.
• The bacteria were found in 23% of the samples from horses that exhibited symptoms of diarrhea, and these included samples from 10 young horses (foals). Significantly, no C. difficile bacteria were identified in any of the samples from healthy adult horses.
• The bacterial strains detected were profiled for the presence of three toxins – A, B, and the binary toxin, which is associated with increased virulence.

Toxin Profiling and Ribotyping

• The majority of the equine isolates were found to be producing toxins A and B, but not the binary toxin (A(+)B(+)CDT(-)).
• Other toxin profiles detected included A(-)B(-)CDT(+) (one isolate), A(+)B(+)CDT(+) (two isolates), and A(-)B(-)CDT(-) three isolates – these classifications define the specific toxin-producing capabilities of the bacteria.
• Ribotyping, a process that categorizes bacteria based on variations in their ribosomal RNA, identified six different ribotypes within the C. difficile isolates. Ribotype 012 was the most common variant.
• Interestingly, two horses (one adult and one foal) were found to harbour two different strains of C. difficile at different time points, characterized by the same toxin profile but different ribotypes.

Significance and Future Directions

• Notably, no isolates were identified as ribotype 078, known to be a significant cause of animal disease overseas. This indicates a potential geographic variation in the types of C. difficile affecting horses.
• All of the isolated C. difficile bacteria were found to be <a href="/metronidazole-for-horses/” title=”Metronidazole (Flagyl®) for Horses: Pharmacology, Clinical Uses & Side Effects”>susceptible to metronidazole and vancomycin – two types of antibiotics commonly used to treat C. difficile infections.
• The team concluded that the current epidemiology of C. difficile in Australian horses is consistent with other parts of the world. However, they highlight the importance of ongoing surveillance to monitor potential changes in this pattern over time.