Significance of the beef, pork and poultry sectors in the onset of Clostridium perfringens food poisoning outbreaks in France
Résumé
Clostridium perfringens is a spore-forming, anaerobic, and ubiquitous pathogen responsible for gastrointestinal diseases in humans and animals. C. perfringens strains are classified into seven types (A–G) based on the combination of toxins that are produced. Types A and F are responsible for C. perfringens foodborne outbreaks (FBO) in France, and the foods most often implicated are meat-based ready meals. Despite very few available studies, the contamination of meat is highly suspected in the slaughtering process through contamination with the intestinal or fecal content of slaughtered animals. With the purpose of assessing the C. perfringens hazard in food safety, the ClostAbat project (ANR2021-CE21-0007) aims to provide information on the frequency, diversity, and pathogenic potential of C. perfringens strains isolated from slaughterhouses in France and to compare them to isolates involved in FBO. Strains were isolated from 8–12 sampling campaigns in three sectors: pig, cattle, and poultry. For each sampling campaign, up to five isolates per sample were collected, and 58–74 samples were performed from various sources, including animals (feces, carcasses, and meat cuts), surfaces (work surfaces and operator tools), and the air of slaughterhouses and cutting plants. The strains' genetic diversity was assessed by PCR-M13 molecular typing, and their toxinotype was determined by PCR targeting the 7 genes encoding major toxins [1]. For further characterization, an agglomerative hierarchical clustering was performed with the purpose of maximizing the genetic diversity among the isolates within a selection of 96 isolates per sector. Out of 418 positive samples, a total of 1724 isolates were characterized. Then, the whole genomes of 288 selected isolates were sequenced, and the level of genetic relatedness among the isolates and the virulence factors they could possess was identified with the application of WGS-based analysis. Additionally, with the use of genomic source attribution models, the origin of isolates responsible for FBO was determined by comparison with strains from various sources, including the environment, slaughterhouses, and clinical strains. This study confirmed the presence of C. perfringens at different steps of the slaughtering process and provided information on potential cross-contamination happening in slaughterhouses. Furthermore, this study also contributed to the availability of epidemiological data for C. perfringens.
