Growth and survival of Yersinia enterocolitica and Escherichia coli O157:H7 in fresh sausages

We investigated the growth and survival of Yersinia enterocolitica and Escherichia coli O157:H7 in vacuum-packed fresh sausages at 6 degrees C. High (400 cfu/g) and low (0.4 cfu/g) multistrain mixtures of Y. enterocolitica and E. coli O157:H7 were inoculated separately in fresh sausages. Sausages were sampled for microbial counts immediately and at 9 and 12 days after the inoculation, and a five-tube most-probable-number method was used for enumeration. The bacterial counts decreased during storage. Both bacteria survived in sausages with the high inoculum and Y. enterocolitica also in sausages with the low inoculum. Y. enterocolitica and E. coli O157:H7 are regularly found in raw material of fresh sausages and even survival of E. coli O157:H7 without growth may present a risk for consumer health.