POLYMERASE CHAIN-REACTION FOR DIAGNOSIS OF MYCOBACTERIUM-TUBERCULOSIS- COMPARISON OF SIMPLE BOILING AND A CONVENTIONAL METHOD FOR DNA EXTRACTION

Although the polymerase chain reaction (PCR) has been used increasingl y for rapid diagnosis of tuberculosis (TB) in clinical specimens, no c onsensus exists regarding DNA extraction protocols. We compared a simp le boiling method to a conventional, labor-intensive chemical method u sing lysozyme and silica particles. The boiling method was performed i n less than 30 min; the chemical method required at least 6 h. A total of 82 clinical specimens (mostly respiratory) from 77 patients were o btained after routine processing from the microbiology laboratory. Aft er DNA extraction by each method, PCR was performed to detect the 123- bp segment of IS6110, and results were compared to culture. Of 20 cult ure-positive specimens, 17 (85%) and 12 (60%) were positive by boiling and chemical methods, respectively. Of 62 culture-negative specimens, 61 (98%) and 57 (92%) were negative by boiling and chemical methods, respectively. The sensitivity was 100 and 92% for the boiling and chem ical methods, respectively, for smears containing more than rare AFB. Our results suggest that boiling method of DNA extraction is more sens itive and no less specific than a conventional chemical method. Larger studies including a variety of clinical specimens are necessary to st andardize the optimal conditions of PCR for diagnosis of M. tuberculos is. (C) 1996 Academic Press, Inc.