Prevalence of cpe-positive Clostridium perfringens in surface-attached soil of commercially available potatoes and its significance as a potential source of food poisoning.

ABSTRACT

OBJECTIVE: We aimed to examine the surface-attached soil of commercially available potatoes in Japan to determine the association between foodborne infection and the circulation of Clostridium perfringens through vegetables, soil, and environments. METHODS: C. perfringens spores were isolated from 30 surface-attached soil samples of potatoes obtained from six regions in Japan. We performed multiplex polymerase chain reaction (PCR) and sequencing to detect the presence of six toxin and plasmid-related genes in the isolates. RESULTS: Sulfite-reducing clostridial spores were detected in 28 (93%) of 30 potato samples, and toxin gene PCR was performed using 613 isolates. The C. perfringens α toxin gene (cpa) was detected in 288 isolates (288/613; 47%) from 25 potato samples (83%), and these isolates were presumed to be the strains of C. perfringens. The toxin types of C. perfringens were classified into type A, in which 73% of isolates had only cpa, followed by type F in 20%, type C in 6%, and type E in 0.003% (1 isolate). The enterotoxin gene (cpe) related to food poisoning was detected in 64 isolates from 9 potato samples (3%). Of these, 59 isolates had cpa and cpe, whereas five had cpa, C. perfringens ß toxin gene, and cpe. All tested cpe-positive isolates had plasmid-type cpe. CONCLUSIONS: The isolation of culturable cpe-positive C. perfringens from the surface-attached soil of commercially available potatoes indicates that potatoes are a potential source of foodborne transmission of C. perfringens.