title: [Frequency of extended-spectrum β-lactamase (ESBL) and AmpC β-lactamase genes in Escherichia coli and Klebsiella pneumoniae over a three-year period in a University Hospital in Korea].
abstract: BACKGROUND
  The aim of this study was to determine the yearly prevalence and genotype distribution of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae collected over a 3-yr period in Gwangju, Korea.
  
  
  METHODS
  Clinical isolates of E. coli and K. pneumoniae collected at Chosun University Hospital from September 15, 2005 to September 14, 2008 were evaluated. Antimicrobial susceptibility testing was performed using the Vitek II system (bioMérieux, USA) and agar dilution methods. Screening for ESBL and AmpC β-lactamase genes was performed using PCR amplification of plasmid DNA followed by direct sequencing of the PCR products.
  
  
  RESULTS
  The percentage of ESBL-producing isolates was 12.6% (196/1,550) for E. coli and 26.2% (294/1,121) for K. pneumoniae. The ESBL gene sequencing results showed that the most prevalent ESBL types were CTX-M (93.5%) and SHV (12.9%) in E. coli, and SHV (73.2%) and CTX-M (46.3%) in K. pneumoniae. The most common ESBL in E. coli was CTX-M-15-like, followed by CTX-M-14-like, SHV-2a-like, and SHV-12-like. The most prevalent ESBL type in K. pneumoniae was SHV-12, followed by CTX-M-14-like and CTX-M-15-like. Fifty-one percent (21/41) of ESBL-producing K. pneumoniae with ESBL types verified by sequencing also had DHA-1-like AmpC β-lactamases. However, none of the ESBL-producing E. coli was positive in the AmpC β-lactamase PCR analysis.
  
  
  CONCLUSIONS
  In this study, the most common types of class A ESBLs identified were CTX-M-15-like in E. coli and SHV-12-like in K. pneumoniae.
authors.affiliation: Research Center for Resistant Cells, Chosun University College of Medicine, Gwangju, Korea.
authors.forename: Xue Min
authors.initials: XM
authors.lastname: Li
authors.forename: Sook-Jin
authors.initials: SJ
authors.lastname: Jang
authors.forename: Il Kwon
authors.initials: IK
authors.lastname: Bae
authors.forename: Geon
authors.initials: G
authors.lastname: Park
authors.forename: Young Sook
authors.initials: YS
authors.lastname: Kim
authors.forename: Jong Hee
authors.initials: JH
authors.lastname: Shin
authors.forename: Dae Soo
authors.initials: DS
authors.lastname: Moon
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Park
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000302:isolation & purification; D005787:Gene Frequency; D005838:Genotype; D006785:Hospitals, University; D006801:Humans; D007711:Klebsiella pneumoniae / Q000235:genetics* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D056910:Republic of Korea; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; C048795:AmpC beta-lactamases; D001618:beta-Lactamases