A UNIVERSITY OUTBREAK OF ESCHERICHIA-COLI 0157 H7 INFECTIONS ASSOCIATED WITH ROAST BEEF AND AN UNUSUALLY BENIGN CLINICAL COURSE/

An outbreak of Escherichia coli O157:H7 infections occurred after a gr aduation banquet at a university in Wisconsin. Sixty-one (32%) of 193 banquet attendees developed a gastrointestinal illness; 2 were hospita lized, none developed hemolytic-uremic syndrome or thrombotic thromboc ytopenic purpura, and none died. The spectrum of illness was unusually mild, with 61% of ill persons reporting nonbloody diarrhea. A strain of E. coil O157:H7, indistinguishable from the outbreak strain by toxi n type, plasmid profile, and pulsed-field gel electrophoresis, was iso lated from an unopened package of an uncooked round of beef from the o riginal shipment of meat. An investigation suggested that both underco oked roast beef and salad cross-contaminated with beef were vehicles o f transmission. These findings demonstrate that meat from beef cattle may transmit E. coil O157:H7, and such infections among young to middl e-aged adults may be mild and may often go undetected.