Characterization of rpoB mutations in rifampin-resistant isolates of
Mycobacterium tuberculosis cultured from the Iranian patients
F Doustdar , A Khosravi , P Farnia , A Bahremand IJMM 2007; 1(1):17-22 ICID: 492274
Article type: Original article
IC™ Value: 3.25
Abstract provided by Publisher
Background and objectives: In this project we investigated the frequency of mutations within the rifampin resistance-determining region (RRDR) of rpoB gene to determine whether this region is useful for molecular detection of rifampin resistant isolates of Mycobacterium tuberculosis from Iranian patients.
Material and Methods: A set of 25 rifampin resistant and 5 randomly chosen fully susceptible M. tuberculosis complex strains obtained from sputum samples of individual patients were investigated. The M. tuberculosis H37RvT and CDC 1551 standard strains were used as controls. Using the specific primers, the entire RRDR of rpoB gene of selected samples was amplified and sequenced directly.
Results: Genetic alterations in the RRDR were present among 96.0% of isolates. The majority of rifampin resistant isolates (72.0 %) showed missense mutations in the core region of rpoB that led to substitutions of amino acids at Ser-531 (60.0 %), His-526 (16.0 %) or Asp-516 (8.0 %). While the codon 531 has been the most common site of nucleotide substitutions worldwide, the frequencies of mutations at the codons 526 and 516 among the Iranian isolates were different from other geographical regions. Mutation at codon 533 was found at higher frequency (8%) comparing to the report from other countries.
Conclusion: The high rate of mutations within the RRDR of the rpoB gene suggests that targeted screening of the RRDR may be feasible for the determination of rifampin resistance in clinical isolates of Mycobacterium tuberculosis from Iran.