Prevalence and molecular characterization of Clostridium difficile isolates from a pig slaughterhouse, pork, and humans in Taiwan

- Pig slaughterhouse showed high levels of cross-contamination with C. difficile.
- The major source of cross-contamination might be scalding water.
- C. difficile ribotype 126 and ribotype 127 were found in slaughterhouse and pork.
- This is the first report in meat of ribotype 127, a potential foodborne pathogen.

Clostridium difficile causes antibiotic-associated diarrhea in both humans and animals. The ribotype 078, predominant in food animals, is associated with community-acquired C. difficile infection, and C. difficile is suggested to be a foodborne pathogen. Recently, the C. difficile ribotype 078 lineage emerged in patients and pigs in Taiwan. This study aimed to investigate the prevalence and molecular characterization of C. difficile isolated from a pig slaughterhouse, retail meat, ready-to-eat meals, and humans in Taiwan. We collected samples from one slaughterhouse (n = 422), 29 retail markets (raw pork, n = 62; ready-to-eat pork, n = 65), and one hospital (non-diarrheal humans, stool, n = 317) in 2015. The isolated C. difficile were subjected to ribotyping and multilocus variable-number tandem-repeat analysis (MLVA). In the slaughterhouse, the isolation rate from carcasses was high (23%, 21/92) and ribotype 126 dominated. Scalding water was found to have C. difficile contamination (44%, 4/9), and two of the seven isolates were ribotype 126. The isolation rates from raw pork and ready-to-eat pork were between 20% and 29%. Ribotypes 126, 127, and 014 were found in raw pork, whereas ribotype 078 was not identified in this study. Eight isolates-seven non-toxigenic isolates and one ribotype 017-were found in non-diarrheal human samples. Notably, MLVA showed that ribotype 126 isolates from the slaughterhouse, pig stool, colons, carcasses, and scalding water were closely genetically related, indicating serious risk for cross-contamination. However, the genetic evidence of foodborne transmission from carcasses to food and humans is still lacking.