RESUMO
Background: Early diagnosis of tuberculosis is critical for its effective management and prevention. Several gene amplifi cation methods are used in the detection of tubercle bacilli from clinical specimens. MPB64 gene and IS6110 region have been identifi ed as potential gene targets for the specifi c detection of Mycobacterium tuberculosis from direct clinical specimens. Objective: The present study was conducted to evaluate the diagnostic utility of simultaneous application of two nested polymerase chain reaction (nPCRs) targeting MPB64 and IS6110 region for the detection of M. tuberculosis genome. Materials and Methods: A total of 100 and 354 clinical specimens from the control group and clinically suspected tuberculosis patients, respectively, were included in the study. nPCRs targeting MPB64 and IS6110 region were performed. Results and Conclusion: All of the 100 clinical specimens from the control group were negative for both nPCRs. Out of the 354 clinical specimens, 339 were positive for both culture and nPCRs, 10 and 5 were positive for culture, and nPCR targeting IS6110 and MPB64 regions, respectively. To conclude, nPCRs targeting MPB64 and IS6110 region are reliable and specifi c targets when applied simultaneously on clinical specimens to attain 100% sensitivity for the detection of M. tuberculosis genome.
RESUMO
Background: In view of the diagnostic difficulties associated with sputum- negative pulmonary TB (PTB), we aimed at exploring if bronchoalveolar lavage (BAL) samples can be subjected to smear- microscopy and rapid mycobacterial culture (by Mycobacterial Growth Indicator Tube (MGIT) method) to achieve improved diagnosis of this condition. Methods: Patients presenting with clinico-radiological features suggestive of pulmonary tuberculosis and whose sputum smears were negative for acid- fast bacilli (AFB) or who could not expectorate sputum were prospectively enrolled in this study. BAL samples collected from them were subjected to smear- microscopy for AFB and micro-MGIT culture. BAL samples were also inoculated on Lowenstein- Jensen (LJ) slants. Results: A total of 105 patients (74 males) were recruited in the study, with a mean (±SD) age of 51 (± 15) years. The diagnosis of PTB was made in 52 patients on the basis of clinico- radiological presentation, with or without microbiological confirmation. Thirty- four patients (65.4 %) had microbiologically confirmed PTB. Of them, AFB were detected in 12 BAL samples, while culture- positivity was noted in 24 and 27 patients by the LJ and MGIT methods respectively. Intertest agreement between the LJ and MGIT methods was found to be significant (ê= 0.655; p= <0.001). However, the mean time to positivity was significantly lower for the MGIT method than for the LJ method (p= <0.001). Conclusion: Examination of BAL samples by smear- microscopy and micro-MGIT culture can, therefore, provide a rapid and definitive diagnosis of PTB in sputum- negative patients.