BACKGROUND: Various primers are being tested for the detection of Mycobacterium tuberculosis DNA. The accuracy of the polymerase chain reaction (PCR) depends on the target sequence used and whether the test will be performed in culture or in clinical specimens. OBJECTIVES: To identify DNA sequences, specifically those commonly reported as targets for diagnosis of tuberculosis (TB), in clinical samples of M. tuberculosis strains. METHOD: Eighty-one clinical samples from suspected TB patients were initially processed and submitted to bacilloscopy (smear) and culture, and PCR was performed with specific primers for the following targets: IS6110, 65 kDa, 38 kDa and MPB64. RESULTS: Smear and culture results were negative in 24 samples, as was the PCR. The 19 samples testing smear positive, as well as the isolated strains, were 100% positive on PCR, with the exception of the 89.4% result from PCR with MPB64 primers. In the 38 smear negative and culture positive samples, PCR results were inconsistent. The primers specific for amplifying the 123 bp IS6110 fragment gave the highest positivity (92.1%), diagnostic agreement (0.9143), co-positivity (94.7%) and co-negativity (100%). CONCLUSION: The IS6110, 38 kDa, MPB64 and 65 kDa sequences were found in the genome of all M. tuberculosis strains isolated in patients from the state of Amazonas. The protocol for processing the clinical samples prior to PCR analysis and the specific primers used to amplify the 123bp IS6110 fragment showed a greater efficiency in diagnosing pulmonary (paucibacillary) tuberculosis in comparison to published data.
Primers; Diagnosis; Mycobacterium tuberculosis
