Effectiveness of the BDProbeTec ET system for detection of Mycobacterium tuberculosis complex in sputum and bronchoalveolar lavage specimens

objective: the diagnostic efficacy of the bdprobetec et mycobacterium tuberculosis (mtb) complex direct detection assay (dtb) performed on bronchoalveolar lavage (bal) specimens and sputum smears was compared with acid-fast bacilli (afb) smear microscopy. method: afb smear microscopy, dtb and culture results of 286 patients with pulmonary tuberculosis were retrospectively reviewed. a total of 120 patients provided expectorated sputum samples, and 166 patients provided bal specimens. culture results and clinical diagnosis were used as gold standards. results: the sensitivity and specificity of the dtb assay in detecting mtb in sputum specimens was significantly higher compared to afb smear microscopy (83.7% and 82.4%, vs. 75.6%, and 41.2%, respectively). the sensitivity and specificity of the dtb assay in detecting mtb in sputum samples was 77.2% and 100% compared to clinical diagnosis, while afb smear had a sensitivity and specificity of 70.3% and 26.3%, respectively. compared to culture, dtb had a sensitivity and specificity of 82.8% and 93.2%, respectively, in detecting mtb from bal specimens; afb smear had a sensitivity and specificity of 41.9% and 87.7%, respectively. compared to clinical diagnosis, dtb had a sensitivity and specificity of 67.2% and 100%, respectively, in detecting mtb from bal specimens; afb smear had a sensitivity and specificity of 34.8% and 79.5%, respectively. conclusions: the superior performance of the dtb assay relative to afb smear microscopy makes it a valuable tool to enable early diagnosis of mtb, thereby improving patient care and reducing transmission.