[Detection of rifampin-resistant Mycobacterium tuberculosis by line probe assay (LiPA)]

A recently described reverse hybridization-based line probe assay is used for the rapid detection of the mutations in the rpoB genes of rifampin-resistant Mycobacterium tuberculosis and for the identification of the M. tuberculosis complex. A multicenter study that included 5 laboratories was performed to evaluate the line probe assay in comparison with the in vitro susceptibility test. A total of 406 mycobacteria isolates which were composed of 103 rifampin-resistant and 230 rifampin-susceptible M. tuberculosis isolates, and 73 mycobacteria other than tubercle bacilli (MOTT), were subjected to this study. All 333 M. tuberculosis isolates were discriminated correctly from MOTT bacilli by a line probe assay. Concordance rates with sequencing results for five wild-type probes (S probes) and four specific mutations (R probes) for detecting the mutations in the rpoB genes were both 100%. The overall concordance rate with the in vitro susceptibility testing results was 98.5% (328 of 333 isolates). These results indicate that a line probe assay kit may be useful for the rapid diagnosis of rifampin-resistant tuberculosis.