Evaluation of the polymerase chain reaction for the detection of Mycobacterium tuberculosis

The development of nucleic acid-based technologies has improved the sensiti vity, specificity and speed of detection of Mycobacterium tuberculosis in c linical samples. Both commercially available and 'in-house' polymerase chai n reaction (PCR) systems are in use, and a significant number of reports co mpare such systems with more traditional diagnostic tools for tuberculosis. Few studies, however, have focused on the reproducibility of the results w hen submitting a sample batch to PCR in different laboratories, especially in developing countries. Consequently, PCR results obtained from six labora tories in six different Latin American countries for samples reconstituted with defined amounts of M. tuberculosis cells were evaluated. Each laborato ry used specific conditions of sample processing, nucleic acid amplificatio n and amplicon detection. Analysis of results allowed large differences in sensitivity and specificity to be observed. We conclude that in its present setting, inhouse PCR cannot be used as a single diagnostic tool for tuberc ulosis, and that special care needs to be taken upon interpretation of resu lts by inclusion of a proper number of positive and negative controls.