Diagnostic performance of genoType® MTBDRplus line probe assay in bronchoalveolar lavage for pulmonary tuberculosis diagnosis in sputum scarce and smear-negative patients

Background: MTBDRplus line probe assay (LiPA) has been endorsed by the World Health Organization for pulmonary tuberculosis (TB) diagnosis. However, its value for Mycobacterium tuberculosis (MTB) detection in bronchoalveolar lavage (BAL) needs exploration. This study determined the diagnostic performance of MTBDRplus in BAL for MTB complex detection and isoniazid/rifampicin resistance in smear-negative and sputum scarce patients. Materials and Methods: Retrospective evaluation of data (January-December 2013) from patients who underwent bronchoscopy was done. Of these, patients with high TB suspicion with available data on acid-fast bacilli (AFB) smear/culture and MTBDRplus were selected. Results of MTBDRplus were compared with AFB smear/culture and drug susceptibility. Sensitivity and specificity of MTBDRplus was determined using TB culture as gold standard. Results: Data on 383 patients who underwent bronchoscopy were collected. Of these, 154 previously untreated TB suspect patients that were either smear negative on sputum microscopy or sputum scarce were selected. Out of 154 patients, 11 were smear positive and 34 patients were AFB culture positive. MTBDRplus detected MTB in 23/34 cases, the sensitivity and specificity being 67.6% and 85% (P < 0.001) versus 32.4% and 100% (P < 0.001) compared to smear microscopy. All smear-positive cases (n = 11) were detected by MTBDRplus. There were no discrepancies between phenotypic drug susceptibility testing and LiPA for isoniazid and rifampicin resistance in patients. Two cases of multidrug-resistant TB were detected. Conclusion: MTBDRplus detected TB more rapidly and accurately than smear microscopy with significant accuracy for isoniazid and rifampicin resistance. Its use in clinical practice would lead to rapid detection and effective management.