Distribution of enterotoxin- and epsilon-positive Clostridium perfringens spores in U.S. retail spices

Abstract

The role of spices as vehicles of foodborne illness prompted an examination of bacterial spores in these products. Here, we report on the levels and characteristics of spores of Clostridium perfringens associated with 247 U.S. retail spices. Forty-three confirmed isolates from 17% of samples were obtained, present at levels ranging from 3.6 to 2,400/g. Twenty-seven (63%) of C. perfringens isolates were positive for the enterotoxin gene (cpe). Seven random spice isolates produced enterotoxin at levels of between 4 and 16 ng/mL, compared with three outbreak (control) strains that each produced enterotoxin levels of .1,024 ng/mL. D958C levels (1.0 to 3.3 min) of spores of four randomly selected spice isolates suggests a plasmid-localized cpe, while one had D958C (.45 min) consistent with chromosomally located cpe. Five of the 43 isolates possessed the epsilon toxin gene (etx, as well as cpe). Foods could easily become contaminated with spores of cpe-positive C. perfringens by the addition of spices. Because of its spore-forming ability, its rapid generation times at elevated temperatures, improper heating, cooling, and holding conditions could lead to elevated levels of C. perfringens in foods, a requirement for its implication in foodborne outbreaks.