RESEARCH Clostridium difficile PCR Ribotypes in Calves, Canada

Abstract

We investigated Clostridium difficile in calves and the similarity between bovine and human C. difficile PCR ribotypes by conducting a case-control study of calves from 102 dairy farms in Canada. Fecal samples from 144 calves with diarrhea and 134 control calves were cultured for C. difficile and tested with an ELISA for C. difficile toxins A and B. C. difficile was isolated from 31 of 278 calves: 11 (7.6%) of 144 with diarrhea and 20 (14.9%) of 134 controls (p = 0.009). Toxins were detected in calf feces from 58 (56.8%) of 102 farms, 57 (39.6%) of 144 calves with diarrhea, and 28 (20.9%) of 134 controls (p = 0.0002). PCR ribotyping of 31 isolates showed 8 distinct patterns; 7 have been identified in humans, 2 of which have been associated with outbreaks of severe disease (PCR types 017 and 027). C. difficile may be associated with calf diarrhea, and cattle may be reservoirs of C. difficile for humans. Clostridium difficile, a gram-positive, spore-forming, anaerobic bacterium, has been associated with pseudomembranous colitis and nosocomial and antimicrobial drug–associated diarrhea in humans (1). Recently, research has suggested that the frequency, severity, and relapse of C. difficile–associated disease (CDAD) are increasing in Europe and North America (1,2). The most common risk factor for CDAD in humans is the use of antimicrobial drugs, particularly fluoroquinolones (3–5). Of recent concern, hypervirulent C. difficile strains have been associated with outbreaks of severe CDAD (2,6). The pathophysiology of CDAD involves colonization of the intestinal tract with C. difficile and production of its toxins (7–9). At least 3 cytotoxins are currently described for C. difficile: toxins A and B (glucosyltransfersases) and a binary toxin (CDT, ADP-ribosyltransferase) (10). Toxin