Clostridium difficile infection in horses: A review

Abstract

Clostridium difficile is considered one of the most important causes of diarrhea and enterocolitis in horses. Foals and adult horses are equally susceptible to the infection. The highly resistant spore of C. difficile is the infectious unit of transmission, which occurs primarily via the fecal-oral route, with sources of infection including equine feces, contaminated soil, animal hospitals, and feces of other animals. Two major risk factors for the development of C. difficile associated disease (CDAD) in adult horses are hospitalization and antimicrobial treatment, although sporadically, cases of CDAD can occur in horses that have not received antimicrobials or been hospitalized. The most common antibiotics associated with CDAD in horses are erythromycin, trimethoprim/sulfonamides, β-lactam antimicrobials, clindamycin, rifampicin, and gentamicin. Clinical signs and intestinal lesions of CDAD infection are not specific and they cannot be used to distinguish infections by C. difficile from infections by other agents, such as Clostridium perfringens or Salmonella sp. The distribution of lesions throughout the intestinal tract seems to be age-dependent. Small intestine is invariably affected, and colon and cecum may or may not have lesions in foals<1-month old. Naturally acquired disease in older foals and adult horses has a more aboral distribution, affecting colon and sometimes cecum, but rarely the small intestine. Detection of toxin A, toxin B or both in intestinal contents or feces is considered the most reliable diagnostic criterion for CDAD in horses. Isolation of toxigenic strains of C. difficile from horses with intestinal disease is highly suggestive of CDAD. A better understanding of pathogenesis, reservoirs of infection, and vaccines and other methods of control is needed. Also further studies are recommended to investigate other possible predisposing factors and/or etiological agents of enteric diseases of horses.

Evaluation of Three Enzyme Immunoassays for Diagnosis of Clostridium difficile–Associated Diarrhea in Foals

“…Anyway, the results of TC took at least 6 days to obtain, even with the simple protocol used in the present study. Considering that CDI in foals is commonly a clinical emergency [4], TC might not applicable for diagnosis. …”

“…In veterinary medicine, this bacterium is the major cause of diarrhea and colitis in several domestic animals and some wildlife [2,3]. In foals, C. difficile causes diarrhea, ranging from a mild, self-limiting form to a peracute and fatal disease [4]. In addition, studies have also shown that strains isolated from humans suffering from C. difficile infection (CDI) exhibit high genetic relatedness with strains isolated from animals, suggesting the possibility of a zoonotic disease [5].…”

Large clostridial glycosylating toxins modifying small GTPases

“…TcdA and TcdB cause CDAD and its more severe form, PMC, in humans and horses [5][6][7]. Thereby, either TcdA or TcdB alone seems to be sufficient to cause fulminant disease, as it can be deduced from mouse and hamster models of infection [116][117][118].…”

Clinical Approach to Commonly Encountered Problems

“…Salmonella and Clostridium species are among the most common causes of infectious diarrhea in horses of any age. 552,[557][558][559][560][561] In certain geographic areas equine neo rickettsiosis (Potomac horse fever) caused by Neorickettsia risticii is also common. 556 Clostridium difficile and Clostridium perfringens are the most common clostridia associated with colitis in horses, although occasionally other species may be involved.…”

“…[557][558][559][560][561] Clostridium perfringens has been cultured from 59% of samples in which no gram-positive rods were visible. Gram stain and spore stain of fecal smears can help to identify and quantitate the bacterial populations present, particularly clostridial species.…”