Enterotoxin production by Yersinia enterocolitica in food samples

Milk and cold meat samples were contaminated with 7 various serogroups of Yersinia enterocolitica strains. The infected food samples were incubated under different conditions of growth, at different temperatures and for different periods of time, then the number of colony forming units was determined and enterotoxin production was assayed by the suckling mice test. The Y. enterocolitica strains multiplied well under varying conditions of growth, but enterotoxin production could be detected only in the meat samples when incubated under shaking at 25 degrees C for 48 h. It may be assumed that performed yersinia enterotoxin is absent from food stored under normal conditions.