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| Year : 1998 | Volume
: 16
| Issue : 4 | Page : 150-154 |
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Polymerase Chain Reaction For Mycobacterium Tuberculosis
R Narasimhan, R. P Ilangho, S Seethalakshmi
Correspondence Address:
R Narasimhan
 Source of Support: None, Conflict of Interest: None  | Check |
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Polymerase chain reaction (PCR) for Mycobacterium tuberculosis was retrospectively analyzed in 101 suspected cases of tuberculosis to evaluate the role of PCR in the diagnosis of pulmonary and pleural tuberculosis. Of the 101 patients, bronchial wash specimens were obtained from 86 suspected pulmonary tuberculosis patients and pleural fluid from 15 cases of pleural effusion. The PCR was done using IS 6110 probe. Based on clinical, radiological, microbiological, histopatho-logical findings and/or past history of anti-tuberculosis treatment, suspected cases of pulmonary tuberculosis (n=86) were divided into four groups: i) active pulmonary tuberculosis (n:37), ii) old pulmonary tuberculosis (n:9), iii) sarcoidosis (n:6) and iv) other non-tuberculosis pulmonary diseases (n:34). The PCR results from bronchial wash specimens were compared with acid fast bacilli (AFB) smear results of bronchial wash specimens. The PCR was positive in 35 of 37 active pulmonary tuberculosis patients, all cases (n:9) of old pulmonary tuberculosis, all cases (n:6) of sarcoidosis and all cases (n:15) of pleural effusions. It was negative in all cases of non-tuberculosis pulmonary disease (n:34). Bronchial wash AFB smears were positive in 25 of 37 active pulmonary tuberculosis patients and were negative in all other groups. Thus the sensitivity of PCR in the diagnosis of pulmonary tuberculosis was 95% and the specificity was 69%. The low specificity of PCR highlights the high false positive rate. Therefore, PCR results have to be interpreted with caution in the diagnosis of pulmonary tuberculosis. However, PCR appears to be useful in the diagnosis of tuberculous pleural effusions. |
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