title: Frequency of Mutations Associated with Rifampicin Resistance in Mycobacterium tuberculosis Strains Isolated from Patients in West of Iran.
abstract: OBJECTIVE
  Tuberculosis (TB) is a devastating infectious disease causing high mortality and morbidity worldwide. The most serious threat related to tuberculosis control is the recent emergence of drug-resistant tuberculosis strains. The aim of the present study was to identify various types of mutations in the rpoB region in rifampicin-resistant strains isolated from sputum of tuberculosis patients.
  
  
  METHODS
  Drug susceptibility of 125 Mycobacterium tuberculosis isolates was determined using the CDC standard conventional proportional method. Target DNA of M. tuberculosis was amplified by polymerase chain reaction, hybridized, and scanned. We used the low cost density array (LCD-array) to detect mutations within the 90-bp rpoB region. Each array is a transparent, prestructured polymer support using a nonfluorescent detection principle based on the precipitation of a clearly visible dark substrate.
  
  
  RESULTS
  Of the 125 M. tuberculosis isolates, 35 (28%) were found to be rifampicin-resistant and using the LCD array revealed point mutations at nine different codons as follows: S512T (AGC→ACC) (20%), D516V (GAC→GTC) (20%), H526D (CAC→GAC) (6%), H526R (CAC→CGC) (20%), H526Y (CAC→TAC) (23%), and S531W (TCG→TGG) (8%), and the most frequent site mutations were L511P (CCG→CTG) (46%), followed by S531l (TCG→TTG) (40%) and D516Y (GAC→TAC) (26%).
  
  
  CONCLUSIONS
  Our data significantly differs from previously reported mutation frequencies for codon 526 (CAC to GAC) among Italian isolates (40.1%) and Greek isolates (17.6%). Phenotypic testing is time-consuming and requires laboratory resources. Microarray rpoB is useful in detecting rifampicin resistance-determining region-associated site mutations of rifampicin-resistant M. tuberculosis isolates.
authors.affiliation: 1Department of Microbiology, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran.
authors.forename: Parviz
authors.initials: P
authors.lastname: Mohajeri
authors.affiliation: 2Student Research Committee, Kermanshah University of Medical Sciences, Kermanshah, Iran.
authors.forename: Hadis
authors.initials: H
authors.lastname: Sadri
authors.affiliation: 2Student Research Committee, Kermanshah University of Medical Sciences, Kermanshah, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Farahani
authors.affiliation: 2Student Research Committee, Kermanshah University of Medical Sciences, Kermanshah, Iran.
authors.forename: Baharak
authors.initials: B
authors.lastname: Norozi
authors.affiliation: 3West Tuberculosis Center, Kermanshah University of Medical Sciences, Kermanshah, Iran.
authors.forename: Sara
authors.initials: S
authors.lastname: Atashi
mesh_terms: D000328:Adult; D000995:Antitubercular Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D003062:Codon; D012321:DNA-Directed RNA Polymerases; D024881:Drug Resistance, Bacterial / Q000235:genetics; D054908:Extensively Drug-Resistant Tuberculosis / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D005260:Female; D015870:Gene Expression; D006801:Humans; D015994:Incidence; D007492:Iran / Q000453:epidemiology; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D059645:Mutation Rate; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D012293:Rifampin / Q000494:pharmacology*; D013183:Sputum / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology
chemical_list: D000995:Antitubercular Agents; D001426:Bacterial Proteins; D003062:Codon; C505805:rpoB protein, Mycobacterium tuberculosis; D012321:DNA-Directed RNA Polymerases; D012293:Rifampin