Rifampicin Monoresistance in Treatment Naïve Pulmonary Tuberculosis Patients




Rifampicin monoresistance, Gene Xpert MTB/RIF assay, 1% proportion method


Background: Multi-drug resistant TB has become an area of growing concern nowadays in treatment naïve
pulmonary TB patients, despite the global efforts in controlling TB. It has emerged as a posing threat to human
survival and major challenge for the NTEP (National Tuberculosis Elimination Programme) in achieving
the global target of ending TB in 2035. Rifampicin monoresistance will contribute towards amplification of
resistance, eventually leading to emergence of MDR, if they are not managed properly.
Objectives: The present study aims to detect Rifampicin monoresistance in treatment naïve or newly
diagnosed pulmonary Tuberculosis patients using GeneXpert MTB/RIF assay and 1% proportion method.
The study is also aimed at evaluating the diagnostic efficacy of both the tests in detecting the same.
Materials and methods: Rifampicin monoresistance (RMR) was diagnosed by molecular/ genotypic testing
(GeneXpert MTB/RIF assay) and conventional phenotypic DST (drug sensitivity testing) method (1%
proportion method) among 162 sputum/ BAL samples obtained from treatment naïve or newly diagnosed
pulmonary Tuberculosis patients.
Results: Out of the 162 samples subjected to GeneXpert MTB/RIF (CBNAAT) assay, Mycobacterium
tuberculosis was detected in 108 (67%) samples and rifampicin resistance (rpoB gene) was detected in 8 (5
%) samples. Whereas phenotypic DST by 1% proportion method detected Rifampicin resistance in 13 (8%)
Conclusion: The study reveals that there is a discordance between molecular/ genotypic test, GeneXpert
MTB/RIF assay and conventional phenotypic DST method,1% proportion method in detecting rifampicin
resistance in newly diagnosed/ treatment naïve pulmonary Tuberculosis patients. Phenotypic method
detected more isolates with rifampin resistance compared to molecular method.