Fate of Escherichia coli O157:H7 in unpasteurized milk stored at 8 degrees C.

Escherichia coli O157:H7 and verocytotoxins were not found in any of 100 unpasteurized milk samples obtained from the bulk tanks of eight dairy farms located in the Puglia and Basilicata areas. Seven E. coli O157:H7 (EHEC) strains were inoculated separately into raw milk samples and then examined periodically to determine the fate of EHEC as influenced by the storage temperature (8 degrees C) and time. There was essentially no change in the viable population of three EHEC strains for up to 14 d. The remaining four strains showed an increase in population from < 2 log to 3 log cfu ml-1 in a time period of between 9 and 17 d. The results indicate good survival or even multiplication of E. coli O157:H7 in raw milk when stored at 8 degrees C and reaffirm the need for pasteurization and holding the milk at < or = 5 degrees C.