EVALUATION OF ROCHE AMPLICOR PCR ASSAY FOR MYCOBACTERIUM-AVIUM COMPLEX IN BRONCHIAL WASHING

SETTING: A commercially available polymerase chain reaction (PCR) test (Roche Amplicor(TM) Mycobacterium avium and M. intracellulare assay-M AC-PCR) designed to detect M. avium complex (MAC) in bronchial washing was evaluated. DESIGN: A total of 141 specimens from 127 patients wit h various pulmonary conditions were examined. Results were compared wi th acid-fast smears, cultures with Ogawa egg medium, as is still commo nly used in Japan, and final diagnoses. RESULTS AND CONCLUSIONS: A tot al of 14 bronchial washing specimens yielded MAC. Six smear-negative a nd culture-positive specimens were all MAC-PCR positive. In eight smea r-negative and culture-positive specimens, six were MAC-PCR positive. The overall sensitivity versus culture was 85.7% (12/14). However, sen sitivity might be over-estimated, as there is a lower recovery rate of MAC with egg-based medium compared with liquid media. In 127 patients , 15 were identified as having pulmonary MAC disease, of whom 13 had p ositive MAC-PCR in bronchial washing. In the remaining 112 patients, M AC-PCR was negative, which suggests that positive MAC-PCR was not a co ntaminated result. However, in terms of sensitivity and speed, we were unable to show any additional clinical benefit for using MAC-PCR as o pposed to liquid media, in which MAC can frequently be detected in 7 t o 14 days.