Equine colitis X associated with infection by Clostridium difficile NAP1/027.

This research article presents the case of a 14-year-old Quarter Horse which developed severe colitis linked to infection by a specific strain of Clostridium difficile (C. difficile). This strain is similar to one known for causing severe disease in humans.

Background

• The study revolves around a 14-year-old Quarter Horse that fell ill over two days, showing symptoms of colic—an extremely painful digestive disorder. Despite treatment, the horse did not respond and was later euthanized (put to sleep to prevent further suffering).
• Postmortem examinations showed multiple symptoms, including congestion of cecal and colonic mucosae, edema, substantial thickening of the intestinal wall, excessive mononuclear cells in the mucosal lamina propria, and extensive submucosal hemorrhage.

Findings

• The researchers identified the presence of toxins A and B from Clostridium difficile in the horse’s system, suggesting that this bacterium was responsible for the illness.
• Using genetic analysis, the researchers isolated large numbers of C. difficile and identified them to be a very specific kind: North American pulsed-field gel electrophoresis type 1, polymerase chain reaction ribotype 027, and toxinotype III.
• This strain of bacteria was found to possess the genes necessary to produce a binary toxin, and also contained a particular deletion in the tcdC gene—anegative-regulator of toxin production. This genetic characteristic could have contributed to the severity of the infection.

Implications

• This strain of bacterial infection has been recognized as the ‘epidemic strain’ in human medicine due to its association with severe Clostridium difficile-associated disease. Hence, the findings suggest the horse had developed a severe, acute form of typhlocolitis, commonly referred to as colitis X.
• The study raises concerns about potential cross-species infections, as this severe C. difficile strain appears to be harmful to horses as well as humans.
• More research is needed to understand the prevalence of this strain in equine populations, its potential transmission routes, and suitable prevention or treatment strategies.