Presence and molecular characterization of Clostridium difficile and Clostridium perfringens in intestinal compartments of healthy horses

Toxigenic C. difficile was isolated from 14/135 (10.3%) samples from 8/15 (53.3%) horses. Between zero and three sites were positive per horse, and multiple sites were positive in four horses. Isolates were recovered from duodenum, jejunum, ileum, right dorsal colon, small colon and rectum. When multiple compartments were positive in a single horse, two different C. difficile ribotypes were always present. Clostridium perfringens Type A (CPE, β2 toxin gene negative) was recovered from the left ventral colon of one horse (0.74%, 1/135 samples). Agreement between faeces and overall C. difficile carrier status was good.Clostridium difficile can be found in different compartments of the gastrointestinal tract of healthy horses, and multiple strains can be present in an individual horse. The prevalence of C. perfringens in healthy adult hoses was low, consistent with previous reports. Faecal samples were representative for presence of C. difficile in proximal compartments in 5/8 horses (63%) but were not representative for the specific strain.Over the past decade Clostridium difficile has emerged as an important enteric pathogen in human [1] and veterinary medicine [2]. Clostridium difficile is an important cause of acute enterocolitis in horses [3-5] with clinical signs ranging from mild self-limiting disease to fulminant necro-haemorrhagic enterocolitis [6]. While clearly a cause of disease in horses, toxigenic strains of C. difficile can also be isolated from faeces of healthy horses, with reported isolation rates of 0% to 8% [5,7-9]. While there are numerous point prevalence studies, there has been limited study of colonization of C. difficile in different anatomic locations throughout the intestinal tract. Clostridium difficile infection (CDI) is typically associated with colonic disease in horses and humans. More recently CDI has also been connected with small intestinal enteritis in humans [10] and with proximal duodenitis jejunitis in horses [11]. This suggests t