Comparison of One-Tube Nested-PCR and PCR-Reverse Blot Hybridization Assays for Discrimination of Mycobacterium tuberculosis and Nontuberculous Mycobacterial Infection in FFPE tissues

Currently, molecular diagnostic assays based on nucleic acid amplification tests have been shown to effectively detect mycobacterial infections in various types of specimen, however, variable sensitivity was shown in FFPE samples according to the kind of commercial kit used. The present study therefore used automated PCR-reverse blot hybridization assay (REBA) system, REBA Myco-ID HybREAD 480^®, for the rapid identification of Mycobacterium species in various types of human tissue and compared the conventional one-tube nested-PCR assay for detecting Mycobacterium tuberculosis (MTB). In conventional nested-PCR tests, 25 samples (48%) were MTB positive and 27 samples (52%) were negative. In contrast, when conducted PCR-REBA assay, 11 samples (21%) were MTB positive, 20 samples (39%) were NTM positive, 8 samples (15%) were MTB-NTM double positive, and 13 samples (25%) were negative. To determine the accuracy and reliability of the two molecular diagnostic tests, the one-tube nested-PCR and PCR-REBA assays, were compared with histopathological diagnosis in discordant samples. When conducted nested-PCR assay, 10 samples (59%) were MTB positive and seven samples (41%) were negative. In contrast, when conducted PCR-REBA test, three samples (17%) were MTB positive, 10 samples (59%) were NTM positive and four samples (24%) were negative. In conclusion, the automated PCR-REBA system proved useful to identify Mycobacterium species more rapidly and with higher sensitivity and specificity than the conventional molecular assay, one-tube nested-PCR; it might therefore be the most suitable tool for identifying Mycobacterium species in various types of human tissue for precise and accurate diagnosis of mycobacterial infection.