Clinical Utility of Bronchial Washing PCR for IS6110 and Amplicor for the Rapid Diagnosis of Active Pulmonary Tuberculosis in Smear Negative Patients / 결핵

BACKGROUND: There is a well recognized interlaboratory variation in the results using the polymerase chain reaction(PCR) to detect the IS6110 sequence. The clinical utility of a commercially developed PCR test(Amplicor) in bronchial washings for detecting pulmonary tuberculosis in smear negative patients was evaluated. The sensitivity and specificity of Amplicor was compared with that of an in-house PCR test used for detecting the IS6110 sequence of Mycobacterium tuberculosis(M.tbc) in the bronchial washing fluid. METHODS: 66 patients whose sputum smear for M.tbc were negative or who could not produce any sputum were recruited from January 1999 to July 1999. They all had a bronchoscopy performed to determine if there were signs of hemoptysis, patients who could not cough up sputum, lung lesion that exclude pulmonary tuberculosis. Pulmonary tuberculosis was diagnosed on the basis of a positive culture or a response to anti-tuberculosis therapy. RESULTS: 19 patients with tuberculosis were identified and samples from 16 patients were later confirmed by culture. Bronchial washing for Amplicor PCR revealed a sensitivity, specificity, positive and negative predictive values of 94.7%, 97.9%, 94.7%, 97.9%, respectively. Using IS6110 based PCR, the sensitivity, specificity, positive and negative predictive values were of 73.7%, 87.2%, 70%, 89.1% respectively. CONCLUSION: Bronchial washing for Amplicor PCR proved to be more useful than IS6110 based PCR in rapidly diagnosing smear negative pulmonary pulmoary tuberculosis in patients where tuberculosis was likely to be differential and rapid diagnosis was essential for optimal treatment.

Detection of Mycobacterium tuberculosis in Sputum by using Polymerase Chain Reaction / 대한임상미생물학회지

BACKGROUND: The recently developed nucleic acid amplification methods may provide us with very sensitive, specific and rapid tests for the detection of M. tuberculosis. So the aim of this study was to compare the commercial Amplicor M. tuberculosis kit and our in-house polymerase chain reaction (PCR) with the conventional culture and direct AFB staining method. Materials and METHODS: Among the total of 2,340 clinical specimens, 1,314 sputum samples were tested for the presence of M. tuberculosis by Amplicor PCR and 1,026 sputum samples were tested by in-house PCR performing with resin matrix preparation and DNA extraction, synthesized primer pair, detection using agarose gel electrophoresis. RESULTS: One hundred-seventeen specimens were positive by Amplicor PCR, 105 were positive by in-house PCR, 185 were positive by culture. The sensitivity of the Amplicor PCR for all of the specimens and for smear-positive and smear-negative specimens was 92.9%, 97.9% and 88.2%, respectively after discrepant analysis. The sensitivity of the in-house PCR for all of the specimens and for smear-positive and smear-negative specimens was 80.0%, 93.6% and 65.5%, respectively after discrepant analysis. The specificity of the Amplicor PCR and in-house PCR for all of the specimens was 97.9% and 99.0%, respectively. CONCLUSIONS: Amplicor PCR was more sensitive than in-house PCR, but there was another problems such as high false positive rate and high cost. So PCR may certainly become very useful in microbiological laboratories if PCR method is selected according to the laboratory conditions.