Comparative Efficacy of Line Probe Assay with Conventional Culture for Detection of Drug-Resistant Mycobacterium tuberculosis

Patama Suttha MD 1 , Nayot Panitantum MD 1 , Piyawadee Chathaisong NS 1 , Unchana Thawornwan MSc 1

Affiliation : 1 Bamrasnaradura Infectious Diseases Institute, Nonthaburi, Thailand

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 MTBDR plus 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

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