Detection and characterization of Clostridioides difficile in broiler slaughterhouses
Résumé
The raise of community-acquired Clostridioides difficile infection over the past decade in humans has resulted in the study of the potential reservoirs of C. difficile strains and risks associated with identified sources. Attention has been paid to the contamination of food as this can be an important route of transmission. Studies currently available in the literature have revealed that a wide range of foods are contaminated by C. difficile, including poultry meat. No data is available regarding the contamination of the poultry meat in France, however a previous study has shown that C. difficile is frequently detected at farm level in broilers. The objective of this study, part of the ClostAbat project funded by the French National Research Agency (CE21-21-007), was to evaluate the contamination by C. difficile at the broiler slaughterhouse level all along the process from animal reception to cutting and to characterize the isolated strains. We performed 12 sampling campaigns in three broiler slaughterhouses with 2 flocks per campaign and collected 29 samples per flock (broiler caeca, meat, surface and ambient air samples) along the slaughter line and in the meat-cutting plan. C. difficile was detected using a culture method (enrichment in supplemented BHI during 7 days at 37°c under anaerobic conditions followed by plating on ChromID) and further characterized (PCR-ribotype, main virulence genes using PCR and antibiotic susceptibility). C. difficile was detected in 42 samples out of the 695 that were collected: 8/24 in transport crates, 14/24 in scalding tank, 11/24 in plucking machine, 1/24 on apron and gloves, and 3/24 in viscera conveyor at the evisceration stage, 1/24 in carcass conveyor at the chilling stage, 1/24 on the floor in the cutting area and in 3 pool of cecal contents/120. Up to 5 isolates were collected per positive sample and further characterized. Among the 198 collected strains, 21 different PCR-Ribotypes were detected, RT002/2 and 014/0 being the most prevalent ones. Genes encoding Toxin A and B were detected in 182 isolates but none of the isolates harboured binary toxin genes. All strains were susceptible to vancomycin, metronidazole, rifampicin and moxifloxacin; 97% were resistant to clindamycin, 2.5% to erythromycin, 3.5% to tetracycline and 0,5% to tigecycline. While C. difficile was detected at the slaughterhouse during the process, neither neckskins nor drumsticks were positive suggesting a low or absence of contamination of the final products in the poultry sector.
