Simultaneous detection of Mycobacterium tuberculosis complex and nontuberculous mycobacteria in respiratory specimens

Many nontuberculous mycobacteria (NTM) species have clinical significance, and the rapid and reliable identification of Mycobacterium tuberculosis complex (MTBC) and NTM species is important. We evaluated the simultaneous detection of MTBC and NTM in respiratory specimens. MTBC and NTM were simultaneously detected and identified by laboratory-developed (LDT) real-time PCR, multiplex real-time PCR/melting curve analysis, rpoB PCR restriction fragment length polymorphisms and the AdvanSure Mycobacteria GenoBlot assay (LG Life Sciences). Eighty-five respiratory specimens from 69 patients showed simultaneous detection of MTBC and NTM. A line probe assay showed 70.6% concordance with LDT. Ten patients (14.5%) had a history of tuberculosis, and eight patients (11.6%) had been previously diagnosed with bronchiectasis. Mixed cultures were present one time in 57 patients (82.6%) and repeatedly in 12 patients (17.4%). MTBC was more frequent in 44 patients (63.8%), and NTM was isolated in seven patients (10.1%). The commonly detected NTM species in the mixed cultures were Mycobacterium intracellulare (29.0%) and Mycobacterium abscessus (29.0%). Co-isolation caused a failure of antitubercular drug susceptibility testing in 2 patients (2.9%). Molecular methods allow MTBC and NTM species to be simultaneously identified in respiratory specimens. NTM isolated with MTBC has clinical significance in some patients and should not be ignored.