[Molecular characterization of embB306 gene in Mycobacterium tuberculosis isolates from tuberculosis patients in Chongqing municipality].
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.
Lin
Hui
H
Department of Epidemiology of Third Military Medical University, Chongqing, China.
Liu
Jie
J
Chen
Lin
L
Jing
Kuan-he
KH
Shen
Jing
J
Zhan
Jian
J
Li
Ya-fei
YF
Xu
Ru-fu
RF
Xiong
Hong-yan
HY
Cao
Jia
J
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*
D004269:DNA, Bacterial; C540269:EmbB protein, Mycobacterium tuberculosis; D010430:Pentosyltransferases