title: Characterization of gyrA and gyrB mutations and fluoroquinolone resistance in Mycobacterium tuberculosis clinical isolates from Hubei Province, China.
abstract: OBJECTIVE
  The study aimed to investigate gyrA and gyrB mutations in Mycobacterium tuberculosis (MTB) clinical strains from 93 patients with pulmonary tuberculosis in Hubei Province, China, and analyze the association between mutation patterns of the genes and ofloxacin resistance level.
  
  
  RESULTS
  Among 93 MTB clinical isolates, 61 were ofloxacin-resistant by the proportion method, and 32 were ofloxacin-susceptible MDR-TB. No mutation in the gyrB gene was found in any MTB strains. In the 61 ofloxacin-resistant isolates, 54 mutations were observed in the gyrA gene. Only one mutation in the gyrA gene was found in ofloxacin-susceptible MDR-TB isolates. In this study, the mutation patterns of gyrA involved seven patterns of single codon mutation (A90V, S91P, S91T, D94N, D94Y, D94G or D94A) and two patterns of double codons mutation (S91P & D94H, S91P & D94A). The ofloxacin minimal inhibitory concentrations (MICs) of three patterns of single codon mutations in the gyrA gene (codons 94, 90 and 91) showed a statistically significant difference (p < 0.0001).
  
  
  CONCLUSIONS
  The gyrA mutations at codons 90, 91 and 94 constitute the primary mechanism of fluoroquinolone resistance in MTB, and mutations at codon 91 in the gyrA gene may be associated with low-level resistance to ofloxacin.
authors.affiliation: School of Public, Tongji Medical College, Huazhong University of Science and Technology, Ministry of Education Key Laboratory of Environment and Health, Wuhan, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.forename: Zhifei
authors.initials: Z
authors.lastname: Chen
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Xia
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.forename: Tian
authors.initials: T
authors.lastname: Chen
authors.forename: Liping
authors.initials: L
authors.lastname: Zhou
authors.forename: Bin
authors.initials: B
authors.lastname: Xu
authors.forename: Shunqing
authors.initials: S
authors.lastname: Xu
mesh_terms: D000293:Adolescent; D000328:Adult; D000995:Antitubercular Agents / Q000494:pharmacology*; D002681:China; D027081:DNA Gyrase / Q000235:genetics*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation / Q000235:genetics*; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D018088:Tuberculosis, Multidrug-Resistant / Q000235:genetics / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000382:microbiology*
chemical_list: D000995:Antitubercular Agents; D024841:Fluoroquinolones; D027081:DNA Gyrase