DIAGNOSTIC-VALUE OF THE STRAND DISPLACEMENT AMPLIFICATION METHOD COMPARED TO THOSE OF ROCHE AMPLICOR PCR AND CULTURE FOR DETECTING MYCOBACTERIA IN SPUTUM SAMPLES

We compared the ability of the semiautomated BDProbeTec-SDA system, wh ich uses the strand displacement amplification (SDA) method, with that of the Recite Amplicor-PCR system and the Septi-Chek AFB culture syst em to directly detect Mycobacterium tuberculosis complex (MTB) and oth er mycobacteria in sputum samples. A total of 530 sputum samples from 299 patients were examined in this study. Of the 530 samples, 129 were culture positive for acid-fast bacilli with the Septi-Chek AFB system ; 95 for MTB, 29 for,ll. avium-M. intracellulare complex (MAC), and 5 for other mycobacteria. The BDProbeTec-SDA system detected 90 of the 9 5 samples culture positive for MTB (sensitivity, 94.7%), and the Ampli cor-PCR system detected 85 of the 95 samples culture positive for RITE (sensitivity, 89.5%). The specificity of each system, based on the cl inical diagnosis, was 99.8% for SDA and 100% for PCR, respectively. Am ong the 29 samples culture positive for ILIAC, the BDProbeTec-SDA syst em detected MAC in 24 samples (sensitivity, 82.8%), whereas the Amplic or-PCR system detected MAC in 24 samples (sensitivity, 79.3%). The spe cificities of the systems were 98.3 and 100%, respectively. The high d egrees of sensitivity and specificity of the BDProbeTec-SDA system sug gest that it should be very useful in clinical laboratories for the ra pid detection of mycobacteria in sputum samples.