Investigation of an Outbreak of Clostridium perfringens in Toyama, Japan, 2023 Using Single-Nucleotide Polymorphism Analysis for Genotyping.

Clostridium perfringens, which produces C. perfringens enterotoxin (CPE), is a major cause of food poisoning because of its gastrointestinal toxicity. In outbreaks of C. perfringens, genotyping is important for identifying the source. We genotyped strains isolated from an outbreak of food poisoning in Toyama Prefecture in 2023, using single-nucleotide polymorphism (SNP) analysis. The strains of C. perfringens were isolated from samples of curry consumed by all the affected patients and from the feces of patients and staff worker. The enterotoxin gene (cpe) was detected in isolates from patients and curry samples. The cpe-negative isolates were found in patients who had consumed curry and in the staff worker. The results of the SNP analysis suggested that the patient and curry isolates were likely from the same source but were unlikely to be related to the staff isolates. The results of SNP and pulsed-field gel electrophoresis (PFGE) analyses were consistent, indicating that the patient and curry isolates originated from the same source. SNP analysis, a whole-genome-based genotyping method, is a promising alternative to traditional PFGE for investigating outbreaks. Further studies are needed to accumulate more experience with genotyping using SNP analysis for the epidemiological investigation of outbreaks of C. perfringens.