Diagnostic Performance of Genotype MTBDRsl Assay (Version 2) for Detecting 2nd Line Drug Resistance TB Compared to Sensititre MycoTBI MIC in MDR-TB Patients

Abstract

Objective: The diagnostic test aimed to compare the GenoType MTBDRsl assay (version 2) and minimum inhibitory concentration (MIC) using a Sensititre MycoTBI MIC plate to detect quinolone and aminoglycoside resistance. Materials and Methods: One hundred thirty-three remaining samples from individuals diagnosed with multidrug-resistance tuberculosis (MDR-TB) and having tested positive for TB cultures between September 2016 and August 2021 were included in the present study. Results: The sensitivity, specificity, PPV, and NPV using GenoType MTBDRsl version 2 compared to MIC of levofloxacin at greater than 0.5 μg/mL were 87.5% (95% CI of 67.6 to 97.3), 98.16% (93.5 to 99.8), 91.30% (72.0 to 98.9), and 97.2% (92.2 to 99.4). Similarly, for moxifloxacin at 2 mg/dL or greater for resistance, the values were 95.4% (95% CI of 77.2 to 99.9), 98.2% (93.6 to 99.8), 91.3% (72.0 to 98.9), and 99.0% (95.0 to 100). The sensitivity, specificity, and diagnostic performances of GenoType MTBDRsl version 2 compared to the MIC of amikacin of greater than 4 μg/mL and kanamycin of greater than 5 μg/mL were 100% (95% CI of 54.1 to 100), 99.2% (95.7 to 100), 99.2% (42.1 to 99.6), and 85.7% (97.1 to 100). Two location mutations at D94G and D94 N/Y were related to a high level of fluoroquinolone with median MIC values of 8 μg/mL of levofloxacin and greater than 4 of moxifloxacin. The mutation at C-14T did not cause resistance in phenotypic patterns. Conclusion: GenoType MTBDRsl (version 2) and MIC determination using Sensititre MycoTBI MIC plate are consistent with each other. Keywords: Sensititre MycoTBI MIC plate; MTBDRsl assay (version 2); Quinolone resistance; Aminoglycoside resistance