Clostridioides (Clostridium) difficile in neonatal foals and mares at a referral hospital

Background: Understanding the epidemiology of Clostridium difficile is important for the development and assessment of infection prevention and control practices, as well as surveillance methods and interpretation of diagnostic testing results.

Objective: Our objective was to longitudinally evaluate C. difficile shedding in neonatal foals and mares admitted to a referral hospital neonatal intensive care unit.

Animals: Foals admitted to a neonatal intensive care unit, along with their dams.

Methods: Rectal swabs were collected from mares and foals at admission, and then approximately every 3 days, when possible. Selective culture for C. difficile was performed and isolates were characterized by toxin gene PCR and ribotyping.

Results: Clostridium difficile was isolated from 103/409 (25%) samples; 65/208 (31%) from foals and 38/201 (19%) from mares. Cumulatively, C. difficile was isolated from at least 1 sample from 50/113 (44%) foals and 30/97 (31%) mares. No association was found between hospitalization day and isolation of C. difficile (P = .13). Twenty-three different ribotypes were identified, with ribotype 078 predominating. Fifteen foals had 2 positive samples during hospitalization. In only 6/15 (40%) foals was the same strain identified both times (5 ribotype 078 and 1 ribotype 012).

Conclusions and clinical importance: Clostridium difficile is an important pathogen in adult horses and foals, and our findings highlight the complexity surrounding the epidemiology of this opportunistic pathogen. It can be found commonly, transiently, and cluster within a facility in the absence of identifiable disease occurrences or clusters.