High occurrence of various Clostridium difficile PCR ribotypes in pigs arriving at the slaughterhouse

Background: Clostridium difficile is recognized as an important cause of nosocomial diarrhoea in humans, especially in association with the administration of antibiotics. Furthermore, C. difficile can not only cause neonatal enteritis in pigs but can also be found in pigs without any clinical disease symptoms. Clostridium difficile had been found on pork samples destined for human consumption. However, little is known about the risk of food-borne transmission. Objective: To elaborate the risk of food-borne transmission of C. difficile via pigs. Animals and methods: The occurrence of C. difficile was assessed in pigs arriving at a slaughterhouse in the Netherlands. Rectal faecal samples from 50 pigs originating from 10 different farms were taken just after the pigs were stunned and bled. These samples were examined using a real-time PCR (BD GeneOhm™ Cdiff Assay) combined with culturing following enrichment. Results: Using real-time PCR, none of the faecal samples were found positive for C. difficile while after culturing following enrichment, 14 out of 50 samples (28%) contained C. difficile. The positive samples were derived from nine different farms and encompassed seven different PCR ribotypes (015 predominant). All isolated C. difficile strains were positive for the toxin A and B genes. Conclusion: These results indicate that C. difficile can be found in faecal samples obtained from pigs after they were stunned and bled in a slaughterhouse. Clinical importance: The potential risk of these findings on food-borne transmission via pigs and associated impact on human health cannot be excluded and needs further study.