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

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). The objective of this work is to evaluate the diagnostic plausibility of the LiPA tests MTBDRplus and MTBDRsl on MDR MTB isolates from Pakistan. 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. 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. 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.