title: [Molecular characterization of embB306 gene in Mycobacterium tuberculosis isolates from tuberculosis patients in Chongqing municipality].
abstract: OBJECTIVE
  To understand the characteristics of embB gene mutation of Mycobacterium tuberculosis (MTB) isolates from tuberculosis patients in Chongqing, and the value of embB306 as a molecular marker used to diagnose ethambutol (EMB)-resistant MTB strains.
  
  
  METHODS
  Direct sequencing was used to analyze the polymorphism of embB mutation in 51 EMB-resistant MTB strains and 50 EMB-sensitive MTB strains. And diagnostic testing was used to evaluate the value of embB306 as a molecular marker of EMB -resistant MTB strains as compared with the traditional sensitivity test.
  
  
  RESULTS
  All 34 of 51 EMB-resistant strains (66.7%) and 3 of 51 EMB-sensitive strains (6%) had had embB306 mutation. The embB306 mutation rate in EMB-resistant strains coming from previously treated case was 87.5%, showing significantly higher than that from new cases (48.1%, P < 0.01); embB306 mutation rate was increased with the number of the resistant drugs; embB306 mutation serving as a marker to diagnose EMB-resistant MTB strains comparing with the traditional sensitivity test, had the rate of sensitivity = 66.7%, specificity = 94.0%, accuracy = 80.2% and Youden index = 60.7%.
  
  
  CONCLUSIONS
  embB306 mutation should be the main mechanism of MTB resistance to EMB in Chongqing, showing an association with the history of the treated and numbers of the resistant drugs. embB306 mutation should be a good marker to diagnose EMB-resistant MTB strains.
authors.affiliation: Department of Epidemiology of Third Military Medical University, Chongqing, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Lin
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.forename: Kuan-he
authors.initials: KH
authors.lastname: Jing
authors.forename: Jing
authors.initials: J
authors.lastname: Shen
authors.forename: Jian
authors.initials: J
authors.lastname: Zhan
authors.forename: Ya-fei
authors.initials: YF
authors.lastname: Li
authors.forename: Ru-fu
authors.initials: RF
authors.lastname: Xu
authors.forename: Hong-yan
authors.initials: HY
authors.lastname: Xiong
authors.forename: Jia
authors.initials: J
authors.lastname: Cao
mesh_terms: D002681:China; D004252:DNA Mutational Analysis; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D006801:Humans; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D010430:Pentosyltransferases / Q000235:genetics*; D018088:Tuberculosis, Multidrug-Resistant / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial; C540269:EmbB protein, Mycobacterium tuberculosis; D010430:Pentosyltransferases