Detection of Mutations in rpob Gene of Clinically Isolated M. Tuberculosis by DNA Sequencing

Sonia Sharma

doi:10.4172/2161-1068.1000156

Abstract

Aim: A population-based study was performed to detect the mutations in 81-bp rifampicin resistance determining region (RRDR) of rpoB gene in clinically isolated M. tuberculosis strains. Methods: Polymerase chain reaction (PCR) mediated direct DNA sequencing was used for rapid detection of rifampicin resistance of M. tuberculosis. Results: Among the 150 isolates, 115 were rifampicin sensitive and exhibited a wild-type pattern on PCR mediated direct sequencing, and remaining 35 isolates were found to be resistant. The codons most frequently involved in mutation were codon 531(40%), 526(23%), and 516(15%).Total twenty four kinds of mutation, which 18 point mutation, 4 insertion & 2 deletion were observed in 81-bp RRDR region of rpoB gene. Conclusion: The sequencing analysis for genotypic evaluation of rifampicin resistance is a highly sensitive assay and provides a practical alternative to in vitro testing in M. tuberculosis. Information on the profile of rpoB mutations in M. tuberculosis provides an improved diagnosis of rifampicin resistance by increasing the efficacy of gene sequencing based test.

Highlights

The diagnosis and control of tuberculosis (TB) is very significant problem in global health
Information on the profile of rpoB mutations in M. tuberculosis provides an improved diagnosis of rifampicin resistance by increasing the efficacy of gene sequencing based test
It has been observed that 95% of rifampcin–resistant strains of M. tuberculosis have a mutation within an 81 bp region of rpoB gene, this region is called rifampcinresistance-determining region (RRDR) corresponding to codons 507-533. [9,10,11]

Summary

Introduction

The diagnosis and control of tuberculosis (TB) is very significant problem in global health. A recent report by the world health organization (WHO) estimated that India is the highest TB-burden country in the world in terms of absolute numbers of incident cases that emerge each year and it contributed one fourth of the estimated global incident TB cases in 2010. The emergence and spread of MDR-TB, is an increasing public problem in India with an estimated number of 110,000 cases spread across the country [2]. Inappropriate treatment can result in the development of resistance to additional antibiotics [4,5] and increase mortality [6]. The detection of rifampicin resistance serves as surrogate marker for detecting MDR-TB [7]. It has been observed that 95% of rifampcin–resistant strains of M. tuberculosis have a mutation within an 81 bp region of rpoB gene, this region is called rifampcinresistance-determining region (RRDR) corresponding to codons 507-533. [9,10,11]

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Conclusion