Clostridium difficile associated with acute colitis in mares when their foals are treated with erythromycin and rifampicin for Rhodococcus equi pneumonia.

The study finds a link between a type of bacteria in horse feces, Clostridium difficile, and acute colitis in mares when their foals are treated with certain antibiotics for lung infection. High antibiotic levels in the foals’ feces could lead to ingestion by the mare, causing colitis, suggesting a potential need for preventive measures.

Research Background and Aims

• The research was conducted in Sweden where some mares, mature female horses, were developing acute, life-threatening colitis when their foals (young horses) were treated with two types of antibiotics, erythromycin and rifampicin, for Rhodococcus equi infection, a bacteria that causes pneumonia in young horses.
• The aim was to determine the cause of this colitis by testing for the presence of various bacteria in the faeces of the mares and their foals.

Results and Findings

• The researchers found that Clostridium difficile, a bacteria that can cause infection and illnesses, was present in the fecal samples taken from mares with diarrhea but was not found in the fecal samples of healthy mares.
• Furthermore, high levels of erythromycin were found in the feces of four foals whose dams (mare mothers) developed acute colitis, indicating that the mares might have accidentally consumed some of the antibiotic in their offspring’s feces. In contrast, the mares of foals with lower concentrations of erythromycin in their feces remained healthy.
• Another observation was that all the mares that tested positive for C. difficile infection either were, or had recently been, hospitalised with their foals, pointing out that this could be a nosocomial or hospital-acquired infection.

Conclusion and Recommendations

• The end result of the study indicates that foals being treated with antibiotics can carry and shed C. difficile in their feces, which if accidently consumed by their mares can lead to colitis.
• The strains of C. difficile found were resistant to both antibiotics used, which favours the growth of this bacteria in the foals’ intestines. This is a significant finding for understanding the proliferation and potential hazards of antibiotic resistance.
• Given these findings, the study recommends routine testing for C. difficile when acute colitis arises in mares whose foals are being treated with erythromycin and rifampicin. It further suggests intervention measures to prevent accidental ingestion of erythromycin by the mares from their treated foals.