Use of spoligotype analysis to detect laboratory cross-contamination.

Spoligotype analysis identified false-positive isolates of Mycobacterium tuberculosis caused by laboratory cross-contamination. Spoligotyping is faster, is less expensive than DNA fingerprinting, and can be used with a variety of media. Patients were reevaluated and had medications discontinued as a result of this investigation. Months of unnecessary patient follow-up and treatment were avoided.