Four laboratory-associated cases of infection with Escherichia coli O157:H7.

An investigation of four cases of infection with Escherichia coli O157:H7 among laboratorians from different clinical laboratories revealed that the DNA fingerprint pattern of each case isolate was indistinguishable from that of an isolate handled in the laboratory prior to illness. These data suggest that the infections were laboratory acquired, and they demonstrate the importance of laboratorians strictly adhering to biosafety practices recommended for the handling of infectious materials.