Diagnostic Plausibility of MTBDRplus and MTBDRsl Line Probe Assays for Rapid Drug Susceptibility Testing of Drug Resistant Mycobacterium tuberculosis Strains in Pakistan

Background: World health organization (WHO) recommends the use of line probe assays (LiPAs) for rapid drug susceptibility testing (DST). However, only a limited number of studies from Pakistan have documented the performance characteristics of line probe assays in testing multi-drug resistant (MDR) strains of Mycobacterium tuberculosis (MTB). Objectives: The objective of this work is to evaluate the diagnostic plausibility of the LiPA tests MTBDRplus and MTBDRsl on MDR MTB isolates from Pakistan. Patients and Methods: This was a cross-sectional study conducted at the Indus hospital, Karachi. LiPA testing was performed on 196 smear-positive samples using BACTEC MGIT 960 as a gold standard. Results: The sensitivity of MTBDRplus for isoniazid and rifampicin was found to be 88.8% and 90.2%, respectively, while sensitivity of MTBDRsl for fluoroquinolones, amikacin/capreomycin, and ethambutol was found to be 72.9%, 81.8%, and 56.6%, respectively. Conclusions: The MTBDRplus and MTBDRsl genotypic testing can serve as useful additional tools for DST in a high-burden country like Pakistan provided it is used in combination with phenotypic testing.