Diagnostic performance of the FluoroType MTBDR assay for rifampicin and isoniazid resistance in routine laboratory setting.

BACKGROUND:  Drug-resistant tuberculosis (DR-TB) continues to be a major public health threat, especially in high-burden settings like South Africa. Rapid and accurate diagnosis of resistance to rifampicin (RIF) and isoniazid (INH) is essential to ensure that patients receive the right treatment as early as possible. Current diagnostic tools, though effective, have limitations. This study addresses the urgent need for faster, reliable alternatives to improve DR-TB detection.

AIM:  The aim of this study is to assess the performance of the FluoroType MTBDR assay in detecting resistance to RIF and INH in a real-world diagnostic setting.

SETTING:  The study was carried out at the National Health Laboratory Services (NHLS) Polokwane Laboratory, a routine laboratory in Limpopo province, South Africa.

METHODS:  We tested 152 Mycobacterium tuberculosis (MTB) isolates collected from the 2023 laboratory repository using the FluoroType MTBDR version 2 assay. These results were compared with those from two established methods: GenoType MTBDRplus and Xpert MTB/RIF Ultra. Whole genome sequencing (WGS) was used to resolve any discrepancies, serving as the reference standard. Diagnostic accuracy was evaluated using sensitivity, specificity and predictive values.

RESULTS:  Of the 152 isolates, 65% were drug-resistant. FluoroType MTBDR showed excellent performance - 100% specificity and 96% sensitivity for RIF resistance and 91% sensitivity and 99% specificity for INH resistance - competing with the GenoType MTBDRplus.

CONCLUSION:  FluoroType MTBDR offers a reliable, rapid alternative for detecting DR-TB, with the potential to improve timely diagnosis and treatment.Contribution: This study highlights the FluoroType MTBDR assay as a valuable diagnostic tool for routine use, contributing to improved TB control strategies, especially in resource-limited, high-burden settings, consistent with the journal's scope.