| Abstract: | OBJECTIVE: To compare the performance of nested polymerase chain reaction (NPCR) withthat of cultures in the detection of the Mycobacteriumtuberculosis complex in pulmonary and extrapulmonary specimens.METHODS: We analyzed 20 and 78 pulmonary and extrapulmonary specimens, respectively,of 67 hospitalized patients suspected of having tuberculosis. An automatedmicrobial system was used for the identification of Mycobacterium spp.cultures, and M. tuberculosis IS6110 wasused as the target sequence in the NPCR. The kappa statistic was used inorder to assess the level of agreement among the results. RESULTS: Among the 67 patients, 6 and 5, respectively, were diagnosed with pulmonaryand extrapulmonary tuberculosis, and the NPCR was positive in all of thecases. Among the 98 clinical specimens, smear microscopy, culture, and NPCRwere positive in 6.00%, 8.16%, and 13.26%, respectively. Comparing theresults of NPCR with those of cultures (the gold standard), we found thatNPCR had a sensitivity and specificity of 100% and 83%, respectively, inpulmonary specimens, compared with 83% and 96%, respectively, inextrapulmonary specimens, with good concordance between the tests (kappa,0.50 and 0.6867, respectively). CONCLUSIONS: Although NPCR proved to be a very useful tool for the detection ofM. tuberculosis complex, clinical, epidemiological, andother laboratory data should also be considered in the diagnosis andtreatment of pulmonary and extrapulmonary tuberculosis. |
