title: Characterization and distribution of drug resistance associated β-lactamase, membrane porin and efflux pump genes in MDR A. baumannii isolated from Zhenjiang, China.
abstract: BACKGROUND
  Acinetobacter baumannii (A. baumannii), especially the multidrug resistant A. baumannii (MDR-AB) is becoming a common opportunistic pathogen in hospital, and constitutes significant public health threats. This study aimed at investigating the relationship between drug resistance with expression of class A-D β-lactamase genes, mutation in membrane porin and over-expression of efflux pump genes among A. baumannii isolated from Zhengjiang, China.
  
  
  METHODS
  Antibiotic susceptibility assays were performed using Kirby-Bauer disc diffusion method. PCR was used to detect β-lactamase genes and carO, oprD, adeR, adeS. Real-time PCR was used to assess the mRNA expression level of efflux pump gene adeB. The software of DNAMAN was applied to assemble oprD and carO sequences, and the sequences were compared with those retrieved from GenBank (http://www.ncbi.nlm.nih.gov/).
  
  
  RESULTS
  27 isolates (61.4%) in this study were MDR-AB, in which five β-lactamases including TEM, CTX-M-2, ADC, OXA-23 and OXA-51 were found, and the positive rate was 96.3% (26), 14.8% (4), 92.6% (25), 88.9% (24) and 92.6% (25), respectively. In addition, the expression level of adeB mRNA was significantly increased in MDR-AB, it might due to adeR mutation. Some mutations were also found in carO and oprD.
  
  
  CONCLUSIONS
  MDR-AB showed high relationship with β-lactamase, mutation in membrane porin and overexpression of adeB, which may directly relates to the mutation in regulating gene adeR.
authors.affiliation: Department of Immunology, School of Medicine, Jiangsu University Zhenjiang 212013, PR China.
authors.forename: Huijian
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Immunology, School of Medicine, Jiangsu University Zhenjiang 212013, PR China.
authors.forename: Lan
authors.initials: L
authors.lastname: Huang
authors.affiliation: Department of Immunology, School of Medicine, Jiangsu University Zhenjiang 212013, PR China.
authors.forename: Prince Amoah
authors.initials: PA
authors.lastname: Barnie
authors.affiliation: Department of Immunology, School of Medicine, Jiangsu University Zhenjiang 212013, PR China.
authors.forename: Zhaoliang
authors.initials: Z
authors.lastname: Su
authors.affiliation: Wuxi Clone Gen-Tech Institute Wuxi 214026, PR China.
authors.forename: Zuhuang
authors.initials: Z
authors.lastname: Mi
authors.affiliation: Department of Laboratory Medicine, The First People's Hospital of Zhengjiang Zhenjiang 212001, PR China.
authors.forename: Jianguo
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Immunology, School of Medicine, Jiangsu University Zhenjiang 212013, PR China.
authors.forename: Vasudevan
authors.initials: V
authors.lastname: Aparna
authors.affiliation: Department of Immunology, School of Medicine, Jiangsu University Zhenjiang 212013, PR China.
authors.forename: Dinesh
authors.initials: D
authors.lastname: Kumar
authors.affiliation: Department of Immunology, School of Medicine, Jiangsu University Zhenjiang 212013, PR China.
authors.forename: Huaxi
authors.initials: H
authors.lastname: Xu
keywords: A. baumannii; efflux pump; membrane porin; multidrug resistant; β-lactamase