Evaluation of Reverse Blot Hybridization Assay for Detection of Mycobacteria

Abstract

Mycobacterial infection is a contagious disease that can occur in all human organs, mostly the lungs (80%). Extrapulmonary mycobacterial infection can be found in several organs including lymph nodes, spine, abdomen, urinary tract, reproductive organs and neuronal organs. Conventional diagnosis of mycobacterial infection can be done by two methods, acid-fast staining (AFB) and mycobacterial culture. Each method has its own limitation, for instance, AFB staining requires large numbers of microbial pathogens in order to be detected, whereas mycobacterial culture takes 2 - 3 months to get the result. In this study, a novel molecular method, the REBA Myco-ID^® test kit using reverse blot hybridization assay, has been used to detect mycobacterial pathogen in specimens collected from various organs containing small number of mycobacteria or non-tuberculous mycobacteria (NTM). Comparative study of the results using real time PCR, DNA sequencing and REBA Myco-ID^® test in 34 samples showed the overall consistency with 100% sensitivity and specificity. In addition, the sensitivity of AFB staining, mycobacterial culture method and REBA Myco-ID^® test were also compared. The sensitivity of AFB staining was found to be 35.3% and that of the culture method was 66.7%. In conclusion, the results suggested that REBA Myco-ID^® test provides a high sensitivity and specificity test results for mycobacterial diagnosis. Despite the high cost, the method is considered worthwhile to be used for diagnosis of mycobacterial infection, particularly extrapulmonary mycobacterial infection, NTM infection and clinical specimens with low number of mycobacterial pathogens.