Molecular characterization and antimicrobial susceptibility testing of Escherichia coli isolates from patients with urinary tract infections in 20 Chinese hospitals

J Clin Microbiol. 2011 Jul;49(7):2496-501. doi: 10.1128/JCM.02503-10. Epub 2011 Apr 27.


A total of 222 urinary Escherichia coli isolates from 20 tertiary hospitals in 15 different provinces and 4 municipalities in mainland China were characterized by antimicrobial susceptibility, phylogrouping, and the presence of plasmid-mediated quinolone resistance genes. A subset of 138 suspected extended-spectrum cephalosporinase (ESC) producers were examined for genes encoding cephalosporin resistance. Forty-three isolates harboring bla(CTX-M-14) or bla(CTX-M-15) were analyzed by pulsed-field gel electrophoresis (PFGE), and plasmids containing these genes were typed using PCR-based replicon typing (PBRT). Thirteen phylogroup B2 bla(CTX-M-14)- and bla(CTX-M-15)-positive isolates were analyzed by multilocus sequence typing (MLST). A frequent occurrence of resistance (>46%) was observed toward cephalosporins, gentamicin, and fluoroquinolones. Among the 222 isolates, 4 qnrS1, 4 qepA, and 16 aac(6')-Ib-cr genes were confirmed. Four major phylogroups (A, B1, B2, and D) and nontypeable isolates (NTs) were found among the isolates, with phylogroup D (54%) being the most common phylogroup. A total of 110 (80%) of the 138 screened isolates harbored bla(CTX-M) genes, with bla(CTX-M-14) (71%) and bla(CTX-M-15) (24%) being the most prevalent of these genes. Nine of the 13 CTX-M-15- or CTX-M-14-containing B2 isolates belonged to ST131. PFGE typing showed a high level of diversity, and plasmid analysis indicated a very large pool of different resistance plasmids mediating the spread of bla(CTX-M) genes in mainland China. An equally very high frequency of resistance and equally high levels of diversity in phylogroups, PFGE types, and plasmids were observed among community- and hospital-acquired E. coli isolates, indicating the presence of a large reservoir in the community and a long-term spread of cephalosporin resistance in China.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • China
  • Cluster Analysis
  • Electrophoresis, Gel, Pulsed-Field
  • Escherichia coli / classification*
  • Escherichia coli / drug effects*
  • Escherichia coli / isolation & purification
  • Escherichia coli Infections / microbiology*
  • Genetic Variation
  • Genotype
  • Hospitals
  • Humans
  • Microbial Sensitivity Tests
  • Molecular Typing*
  • Multilocus Sequence Typing
  • Plasmids / analysis
  • Polymerase Chain Reaction
  • Urinary Tract Infections / microbiology*
  • beta-Lactamases / biosynthesis
  • beta-Lactamases / genetics


  • Anti-Bacterial Agents
  • beta-Lactamases