Direct detection of Mycobacterium tuberculosis complex strains from sputum samples by nested PCR method

Abstract

The purpose of this study was to detect the presence of Mycobacterium tuberculosis complex strains in sputum samples by IS6110-based nested polymerase chain reaction (PCR). The sputum samples of 120 patients with pulmonary tuberculosis were collected. After decontamination procedure, a portion of the sputum samples was inoculated on Löwenstein-Jensen medium and then the samples were incubated at 35-37°C, for 4-8 weeks. Tuberculosis bacilles were identified in 105 out of 120 sputum cultures collected from the patients with tuberculosis. Therefore, the direct sputum samples and the DNAs extracted from the culture of those 105 patients were used for amplification of IS6110 gene region by nested PCR. In the result of the nested PCR method, 78 (74.29%) of the direct sputum samples were found to be positive for M. tuberculosis complex, while 84 (80%) of the culture samples were positive. When the results of the direct sputum samples were compared to the culture samples, the sensitivity and specificity of nested PCR from direct sputum samples were 92.8% (78/84), and 100% (21/21), respectively. This study has shown that nested PCR method is a practical, sensitive and specific method for the detection of M. tuberculosis complex strains from sputum samples. © Gülhane Askeri Tip Akademisi 2006.