Low occurrence of Clostridium difficile in fecal samples of healthy calves and pigs at slaughter and in minced meat in Switzerland

Clostridium difficile is a cause of diarrhea and colitis in humans. The increase of incidence and severity of C. difficile infections in humans in past years is due, at least in part, to the emergence of more virulent strains (PCR ribotypes 027 and 078). Recent studies describe the occurrence of hypervirulent strains in ground meat products. Therefore, food animals and food need to be assessed for their possible role as vectors of C. difficile to humans. In this pilot study, fecal samples of 204 calves and 165 pigs, as well as 46 minced meat products were investigated to determine the occurrence of C. difficile in farm animals at slaughter and in ground meat products at the retail level in Switzerland. C. difficile was isolated from only one fecal sample of a calf. All samples from pigs and ground meat were negative. Further characterization revealed that the isolated strain harbored genes for toxins A and B as well as binary toxin, and belonged to the ribotype 078. Based on these results, low occurrence of C. difficile in farm animals at slaughter and retail ground meat in Switzerland is postulated. However, further studies are necessary to confirm these preliminary data and to assess future trends.