title: [Study on phenotypic and genotypic characterization of clinical multidrug-resistant Escherichia coli isolates].
abstract: OBJECTIVE
  To study the mechanisms on drug susceptibility and resistance of clinically multidrug-resistant Escherichia coli isolates, to provide information on related treatment.
  
  
  METHODS
  The susceptibility of E. coli strains that isolated from different kinds of samples in the last 3 years on drugs was analyzed by agar dilution test, with strains that exhibiting resistances to cefotaxime, ciprofloxacin and amikacin simultaneously collected for further analysis. Resistant genes which mediate resistance to β-lactamases, fluoroquinolone and aminoglycoside as well as phylogenic type were detected by PCR amplification while genetic relation was analyzed by PFGE. Transferability of resistant plasmids was identified by conjugation test.
  
  
  RESULTS
  In total, 137 multidrug-resistant E. coli isolates were collected. Only 1% of the isolates exhibited resistance to both imipenem and meropenem while 4% of the strains were resistant to piperacillin/tazobactam. Most (85%) of the isolates were positive to ESBL and majority of them produced CTX-M. Target substitution and production of methylases were the main mechanisms causing resistance to fluoroquinolones and aminoglycosides respectively.
  
  
  CONCLUSIONS
  The main source of clinical multidrug-resistance was collected from urine samples. Carbapenem and enzyme inhibitor-containing antibiotics seemed to be the available antibiotics that were sensitivity to the clinically multidrug-resistant E. coli isolates.
authors: Department of Laboratory Medicine, The 305th Hospital of PLA, Beijing 100017, China.
authors: Hui-zhong
authors: HZ
authors: Wang
authors: Hang
authors: H
authors: Sha
authors: Qian
authors: Q
authors: Chen
authors: Yan-ju
authors: YJ
authors: Guo
authors: Bing-hua
authors: BH
authors: Zhu
authors: Shao-hui
authors: SH
authors: Wang
authors: De-lu
authors: DL
authors: Gao
mesh_terms: D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D008826:Microbial Sensitivity Tests