Prevalence of Clostridioides difficile in hospitalized neonatal mare-foal pairs from Alberta and direct comparison of fecal culture with toxin gene detection.

Clostridioides (Clostridium) difficile is an important pathogen in the feces of adult horses and foals. It can be clinically diagnosed using several testing methods, including culture isolation and, more commonly, direct toxin gene detection from feces using molecular methods. The importance of monitoring C. difficile shedding in foals or dams during hospitalization remains unclear. The objectives of this study were to determine the prevalence of C. difficile fecal shedding in mare-foal pairs and to compare detection using isolation and a commercial real-time polymerase chain reaction (qPCR) for toxin A and B genes in feces. Foals and their mares admitted to a veterinary hospital were enrolled in the study and their fecal samples were tested for C. difficile toxin A and B genes using qPCR and by culture using selective media. A total of 66 mare-foal pairs was included. Overall, C. difficile fecal qPCR for toxin A and B genes was positive in 29/132 samples from mares and foals and all positive samples originated from foal fecal samples (29/66). A total of 95 samples were negative on both testing modalities (61 mares and 34 foals) and 24 samples were positive on both tests (24 foals). Eight samples (5 mares and 3 foals) were culture positive and qPCR negative, although all of the culture isolates were positive for A and B genes on subsequent conventional PCR testing. Five samples were positive for toxin genes using qPCR and negative using culture. The most common ribotype detected was 078. Two mare-foal pairs cultured positive, of which one pair shared the same ribotype.