Research article Evaluation of Genotype MTBDRplus Assay for identifying Multidrug Resistant Mycobacterium tuberculosis isolates in Nepal

Abstract

Background and Objectives: Multidrug-resistant (MDR) Mycobacterium tuberculosis strains are serious threats to the control of tuberculosis and comprise an increasing public health problem. Rapid detection of such strains is quite critical in timely management of such issues. The study was performed with an objective to compare Genotype MTBDRplus reverse hybridization probe assay (Hain Lifescince, GmBH, Nehern, Germany) with culture based proportion method for rapidly identifying MDR-TB strains from suspected multi drug resistant cases, referred to GENETUP Kathmandu, Nepal.

Rapid Detection of Rifampicin and Isoniazid Resistant Mycobacterium tuberculosis Using Genotype MTBDRplus Assay in Nepal

“…S531L missense mutation that led amino acid substitutions of serine to threonine was most common in rpoB gene accounting for 50% (17/34) of all RIF resistant isolates. Similar result was found in South Vietnam [ 20 ] but it was found to be less frequent than in Thailand (63.6%) [ 21 ] and India (72%) [ 22 ] and more frequent than in a study from Nepal (37.14%) [ 16 ]. Amino acid substitution of aspartate to valine at 516 codon of rpoB gene was observed in 23.5% (8/34) of the RIF resistant strains studied.…”

“…Amino acid substitution of aspartate to valine at 516 codon of rpoB gene was observed in 23.5% (8/34) of the RIF resistant strains studied. This frequency was higher than recent studies reported from Nepal (5.71%) [ 16 ] and India (3.03%) [ 22 ]. Although various frequencies of mutation (2.8%–40%) are observed geographically in different regions of the world at codon 526 of rpoB gene substituting amino acid histidine [ 16 , 19 , 23 , 24 ], no mutation was observed in this gene region in this study.…”

“…Sensitivity of the assay for RIF resistance in this study was lower than reported from various meta-analyses, where calculated pooled sensitivities of assay range from 98.1% (95% CI, 95.9%–99.1%) [ 12 ] to 99% (95% CI, 96%–100%) [ 13 ] while it was higher than in South Africa (85.7%, 95% CI, 57.2–98.2%) [ 14 ]. Similarly, sensitivity of the assay for INH resistance in this study was higher than reported in Caribbean (35–73%) [ 15 ], Germany (88.4%) [ 7 ], and South Africa 62.1% [ 14 ] while it was lesser than in Nepal [ 16 ]. Comparing to various meta-analyses studies where calculated pooled sensitivities of assay range from 84.3% (95% CI, 76.6%–89.8%) [ 12 ] to 96% (93–98%) [ 13 ], sensitivity of the assay in our study for INH resistance is moderate.…”

Use of Genotype MTBDRplus Assay for Diagnosis of Multidrug-Resistant Tuberculosis in Nepal

“…In the present study, the predominant mutation for RIF resistance was found to be in rpoBS531L (71%), which was in agreement with the finding by Yadav et al (72%) [ 5 ]. Lower rates of S531L missense mutation in rpoB gene in comparison to our study were reported by Sharma et al (50%) [ 2 ] and Dahal et al (37.1%) [ 8 ]. In our study, the substitution of aspartate by valine at codon 516 of rpoB gene was found in 4.8% of the RIF resistant isolates which was similar to the findings of the studies in Nepal (5.7%) [ 8 ] and India (3.%) [ 5 ].…”

“…Lower rates of S531L missense mutation in rpoB gene in comparison to our study were reported by Sharma et al (50%) [ 2 ] and Dahal et al (37.1%) [ 8 ]. In our study, the substitution of aspartate by valine at codon 516 of rpoB gene was found in 4.8% of the RIF resistant isolates which was similar to the findings of the studies in Nepal (5.7%) [ 8 ] and India (3.%) [ 5 ]. In the present study, mutation in rpoBH526Y site was observed in 3.2% of the RIF resistant isolates.…”