A Unique Strain of Escherichia coli O157:H7 That Produces Low Verocytotoxin Levels Not Detected by Use of a Commercial Enzyme Immunoassay Kit

In June 1996, a food-borne outbreak due to Escherichia coli O157:H7 swept through Japan affecting more than 9,000 people. This outbreak showed no sign of subsiding until late August 1996, and the government encountered major difficulties in controlling the outbreak. Because of the paucity of epidemiological information concerning this pathogen in Hong Kong, small outbreaks and sporadic cases of infection due to E. coli O157:H7 may go undiagnosed and unrecognized. To monitor the role of this pathogen in human disease in Hong Kong, including hemorrhagic colitis, uncomplicated diarrhea, and hemolytic uremic syndrome, screening for E. coli O157:H7 by use of MacConkey sorbitol agar was initiated in major hospitals in late 1996. We describe the first reported cases of infection due to E. coli O157:H7 in Hong Kong.