PCR can help early diagnosis of pulmonary tuberculosis

One hundred and fifty-one patients, clinically suspected for pulmonary tuberculosis (age: 31 +/- 13 years, male/female: 112/39), were investigated to evaluate the diagnostic potential of polymerase chain reaction (PCR) based detection of the Mycobacterium tuberculosis complex in sputum. The diagnostic efficacy of PCR was compared with culture of Mycobacterium tuberculosis on egg-based Lowenstein-Jensen modified medium. PCR detected 71.5% (108/151), whereas culture detected 66.2% (100/151) of the clinically suspected patients. There was a significant association between the results of PCR and culture (chi2 = 59.524, p < 0.001). However, 23.2% (35/151) samples were found negative in both culture and PCR. Considering culture as the gold standard, the sensitivity of the PCR was 92%. and its specificity 70%. This lower apparent specificity may be due to the higher sensitivity of PCR.