Enterotoxin production by Yersinia enterocolitica and Yersinia enterocolitica-like microbes at 22 degrees C and 37 degrees C.

A total of 32 strains of Yersinia enterocolitica and Y. enterocolitica-like microbes were examined for their ability to produce E. coli ST-like enterotoxin when grown at 22 degrees C and 37 degrees C, using the infant mouse assay. Enterotoxin production was indicated for 19 (59%) of the 32 strains examined. Nine of ten sucrose non-fermenting strains belonging to O-serogroup 28 produced enterotoxin at both 22 degrees C and at 37 degrees C. Eight of these strains were obtained from the intestinal contents of apparently healthy small mammals or from water samples at three different localities in Norway. One O-serogroup 28 culture was a reference strain received from Institut Pasteur, Paris. With the exception of O-serogroup 28, enterotoxins were detected only after incubation at 22 degrees C. The infant mouse assay was positive for all the four clinical isolates belonging to O-serogroup 3/biotype 4. Six of 13 different reference strains were positive in this assay.