Laboratory investigation of an Escherichia coli O157:H7 strain possessing a vtx2c gene with an IS1203 variant insertion sequence isolated from an asymptomatic food handler in Japan

We isolated an Escherichia coli O157:H7 strain that was negative for verocytotoxin production, but positive for the vtx2 gene using commercial kits, from an asymptomatic food handler. The laboratory investigations revealed that a 1310-bp insertion sequence, IS1203 variant, was present in the B subunit-coding region of the vtx2c gene.