Evaluation of the genotype MTBDRplus assay for the diagnosis of tuberculosis and rapid detection of rifampin and isoniazid resistance in clinical specimens

Aim: To determine the performance of the Genotype MTBDRplus assay for diagnosis of tuberculosis and rapid detection of rifampin (RIF) and isoniazid (INH) resistance in clinical specimens.Materials and methods: A total of 90 clinical specimens of 57 patients (69 sputum samples, 11 bronchoscopic aspirates, 5 bronchoalveolar lavage, 4 deep tracheal aspirate, 1 lymph aspirate) sent to the Ege University Medical Faculty, Department of Medical Microbiology, Mycobacteriology Laboratory between December 2007 and 2009 during the clinical routine were included in the study.Results: Overall 80 valid results were obtained for 90 clinical specimens (88.9%) with MTBDRplus. While 74 of 82 (90.2%) smear positive specimens gave interpretable results by MTDRplus, 2 of 8 smear negative specimens gave invalid results. The overall rates of concordance between the results of the MTBDRplus assay and those of the drug susceptibility testing for the assessment of RIF and INH resistance were 97.5% (78/80) and 98.8% (79/80), respectively.Conclusion: Although the MTBDRplus assay could be a useful tool for rapid identification of RIF- and INH-resistant Mycobacterium tuberculosis in both clinical samples and strains, the test results must always be confirmed by culture and drug susceptibility testing.