Isolation and characteristics of Yersinia enterocolitica-like bacteria from meats.

Seventeen Yersinia enterocolitica-like isolates from vacuum-packaged beef and lamb are described. A majority of the isolates were motile at 25 degrees C but not at 36 degrees C, utilized citrate at 25 degrees C (delayed or negative at 36 degrees C) and produced acid from rhamnose, raffinose and melibiose. Increases in count of Y. enterocolitica occurred on raw beef stored at 0--1 degrees C over a 10-day period. No viable Y. enterocolitica were detected in beef roasts which were inoculated with about 3 x 10(6) cells/g and subsequently heated to a final internal temperature of 60--62 degrees C. Y. enterocolitica counts of inoculated beef steaks stored at 1--5 degrees C for 21--35 days were consistently higher in the more oxygen-permeable films than in vacuum packages. Colonies of Y. enterocolitica and related bacteria from meats produced shiny, enamel-black colonies on bismuth sulfite agar with plate incubation at 25 degrees C for 3--5 days.