title: [Co-existence of resistance genes and their association with the genetic marker of integrons among multi-resistant Escherichia coli isolates].
abstract: OBJECTIVE
  To investigate co-existence of resistance genes (beta-lactamases, BLs, and aminoglycoside-modifying enzymes, AMEs) and their association with the genetic marker genes of Class I, II, III integrons carried by multiresistant Escherichia coli isolates.
  
  
  METHODS
  We used VITEK-GNS to determine the susceptibility of 136 isolates to 14 antibiotics, disc agar diffusion test to confirm ESBL-producing isolates, PCR to analyze BLs, AMEs and integrons genes, conjugation and plasmids extraction to locate the methylase genes.
  
  
  RESULTS
  We found that 70.59% of the isolates produced ESBLs. They showed stronger resistance against 9 antibiotics than isolates without ESBLs in 14 antibiotics. PCR amplification showed that the positive rate of BLs, AMEs and qacEdelta1-sul1 was 96.32% , 100% and 94.12%, respectively, but Class II, III integrons genes were negative. Only one strain was oprD2 gene negative. 90.44% of the isolates were both positive for BLs and qacEdelta1-sul1 genes, and 94.12% for AMEs and qacEdelta1-sul1 genes, but there was no statistical significance. 90.44% of the isolates were all positive for the 3 genes. 12 strains carried 16S rRNA methylase genes including armA (2.21%), rmtB (7.35%) while rmtA, rmtC, rmtD were negative. The conjugation assay and plasmids mapping results showed that the methylase genes were located on the 23 kb plasmid, and the efficiency of transformation was 83.3%.
  
  
  CONCLUSIONS
  The results suggested that there was a tight correlation between the 3 genes (BLs, AMEs and qacEdelta1-sul1) and the incidences of multi-resistance of Escherichia coli, but there was no correlation of the incidence of multi-resistance with Class II, III integrons. 16S rRNA methylase genes harboured plasmids of -23 kb which transformed other isolates within the same strains efficiently.
authors.affiliation: School of Clinical Laboratory and Life Science, Institute of Microecology, Wenzhou Medical College, Wenzhou 325000, China. handongqing1122@163.com
authors.forename: Dongqing
authors.initials: D
authors.lastname: Han
authors.forename: Junwei
authors.initials: J
authors.lastname: Huang
authors.forename: Zhongbo
authors.initials: Z
authors.lastname: Shang
authors.forename: Rong
authors.initials: R
authors.lastname: Xu
authors.forename: Yongliang
authors.initials: Y
authors.lastname: Lou
authors.forename: Xiushu
authors.initials: X
authors.lastname: Chen
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D032023:Integrons; D008826:Microbial Sensitivity Tests; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D001618:beta-Lactamases