Bacteriophage typing of Mycobacterium tuberculosis cultures from incidents of suspected laboratory cross-contamination.

Bacteriophage typing was performed on 235 Mycobacterium tuberculosis cultures submitted from 31 laboratories. In each instance, either the attending physician questioned the misdiagnosis of tuberculosis or the laboratory supervisor suspected that laboratory cross-contamination had occurred. Phage typing data confirmed these suspicions. Phage typing is a useful adjunct in the investigation of suspected cross-contamination of laboratory cultures of M. tuberculosis.