A blind study of the polymerase chain reaction for the detection of Mycobacterium tuberculosis DNA. Azay Mycobacteria Study Group.

Setting: Nine French laboratories routinely involved in mycobacterial work.

Objective: To assess the detection of Mycobacterium tuberculosis in experimental samples by polymerase chain reaction (PCR) using the insertion sequence IS6110 as a target for deoxyribonucleic acid (DNA) amplification.

Design: Nine laboratories participated in a blind study of the detection of M. tuberculosis by PCR in 20 coded samples containing either a definite number of M. tuberculosis complex (positive samples) or environmental mycobacteria (four samples) or no mycobacteria (five samples).

Results: Five laboratories reported false-positive PCR results, with an average rate of 7%. All laboratories except one reported positive PCR results for samples containing 10(5) cfu/ml or more. M. tuberculosis DNA was detected in two thirds of samples containing 10(4) and 10(3) cfu/ml, and in one third of the samples containing 10(2) cfu/ml.

Conclusion: The results of the study suggest that PCR using IS6110 as a target for DNA amplication is neither very sensitive nor really specific for the detection of M. tuberculosis.