Survival of Shiga toxin-producing Escherichia coli O157 in marine water and frequent detection of the Shiga toxin gene in marine water samples from an estuary port

Shiga toxin-producing Escherichia coli (STEC) O157 was investigated with re spect to its halotolerance and whether it can survive in marine water. STEC O157 could multiply in a medium containing 5% NaCl and in sterilized marin e water, and could survive in unsterilized marine water for at least 15 day s. On the basis of these results, we postulated that STEC O157 may survive in natural marine water, and attempted to isolate the bacterium and Shiga t oxin gene (stx) from marine water in Japan. The stx, comprising stx(1), and stx(2), was detected from marine water samples by PCR. STEC and other sts- positive bacteria, however, could not be isolated from these samples in thi s study. These results indicate that stx-positive bacteria may survive in m arine water and suggest the necessity of a survey.