Evaluation of the Enhanced Amplified Mycobacterium Tuberculosis Direct Test for Direct Detection of Mycobacterium tuberculosis Complex in Respiratory Specimens

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Abstract
Objective.—To evaluate the performance of the enhanced Mycobacterium Tuberculosis Direct Test (E-MTD), for the direct detection of M tuberculosis complex (MTBC) in respiratory specimens. Design.—Two hundred seventy-four respiratory specimens from 151 patients in respiratory isolation were tested with the E-MTD, and the results were compared with the results of mycobacterial smear, culture, and the earlier form of the test, MTD-1. Results.—Forty-one specimens were culture positive for mycobacteria (20 MTBC and 21 nontuberculous mycobacteria), 23 of which were smear positive (16 MTBC, 7 nontuberculous mycobacteria). Twenty-four specimens were positive by E-MTD, and 21 were positive by MTD-1. Of the 20 MTBC culture-positive specimens, 19 were positive by the E-MTD and 19 were positive by the MTD-1. The remaining specimens were MTBC negative by all methods. After resolution of discrepancies, the sensitivity, specificity, and positive and negative predictive values were 95.2%, 100%, 100%, 99.6% for the MTD-1 and 95.2%, 98.8%, 87.0%, and 99.6%, for the E-MTD. For the E-MTD smear-positive and smear-negative specimens, these same values were 93.8%, 100%, 100%, and 87.5% and 100%, 98.8%, 62.5%, and 100%, respectively. Conclusion.—The results suggest that the E-MTD is a reliable method for the direct detection of MTBC in smear-positive respiratory specimens.