Background: Multidrug-resistant tuberculosis [MDR-TB] has emerged as an important global public health threat. As gold standard for drug-resistant tuberculosis diagnosis, TB culture and drug susceptibility testing [DST] results still take several weeks. A new molecular diagnostic technique, or commercial line probe assays [LPA], has been developed for rapid detection of drug-resistant TB.

Objective: To compare the efficacy of a LPA for rapid detection of rifampicin [RIF] and isoniazid [INH] resistant tuberculosis in clinical specimens with conventional method.

Materials and Methods: The LPA (GenoType MTBDRplus assay) was performed directly on 54 consecutive smear positive specimens at the clinical microbiology laboratory of Bamrasnaradura Infectious Diseases Institute [BIDI], Thailand between January 2014 and December 2014 for the detection of RIF and INH resistance TB. Results were compared with conventional liquid culture and DST.

Results: Overall concordance of RIF and INH susceptibility results between LPA and conventional culture with DST was 87.0% and 92.6%, respectively. Compared with conventional method, the sensitivity and specificity were subsequently 100% and 86.5% for the detection of RIF resistance; whereas, 100% and 92.1%, respectively, for the detection of INH resistance by LPA.

Conclusion: LPA is highly sensitive for diagnosis and detection of drug-resistant tuberculosis, with more diagnostic accuracy in INH resistance than RIF resistance when performed directly on smear positive specimens.

Keywords: Line probe assay, Conventional culture, Drug resistance, Tuberculosis