Occurrence of Yersinia spp. in raw beef, pork and chicken.

One hundred and twenty raw ground beef, pork and chicken samples from ten local grocery stores during a one year period were assayed for the presence of Yersinia spp., using direct and postenrichment KOH treatment. Seven thousand and fifty-five different isolates were recovered from 119 (99%) samples of beef and pork and 118 (98%) samples of chicken, including 27 Yersinia enterocolitica serotype 03 biotype 3B phage type 2 (4 pork samples), 4 Y. enterocolitica serotype 03 biotype 4 phage type 8 (3 pork samples), 4,066 Y. enterocolitica biotype 1, 2,194 Yersinia intermedia, 509 Yersinia frederiksenii, and 251 Yersinia kristensenii. Y. enterocolitica serotype 03 was isolated from 6 pork samples, including simultaneously isolation of both biotypes 3B and 4 from one sample. There was the negative correlation between the incidence of isolation of serotype 03 and the environmental temperature, but other environmental Yersinia spp. were frequently isolated through the year. Y. enterocolitica serotype 03 isolates were counted by alkali direct treatment at less than 10(3) cells per g of pork samples, and environmental Yersinia spp. at less than 10(5) cells per g of beef, pork and chicken samples. This may be the first evidence that some pork is contaminated with at least 10(3) Y. enterocolitica serotype 03 cells per g.