title: Extended spectrum cephalosporin resistance among clinical isolates of Enterobacteriaceae in West Norway during 2006-2013; a prospective surveillance study.
abstract: Routine surveillance of resistance to broad-spectrum cephalosporins in Enterobacteriaceae and phenotypic identification of underlying mechanisms using a simple strategy was commenced in 2006 at our laboratory, serving West Norway. This report focuses on the results until 2013. The classical plasmid-mediated extended spectrum beta-lactamase (ESBLA) among clinically relevant Escherichia coli isolates showed an increase from 0.6% to 4.3% during the surveillance period, while prevalence for other mechanisms remained stable, below 0.7%. ESBLAin Klebsiella pneumoniae had similar prevalence in 2006 (0.6%) and 2013 (4.4%), but in between it peaked to 3.9% in 2008 and to 9.3% in 2011. Within the other species, the numbers of clinically relevant isolates and isolates-producing ESBLAwere much lower. An increasing resistance due to hyperproduction of AmpC enzymes was seen in Enterobacter and Citrobacter, with prevalence increasing from 18% and 12.2% in 2006 to 27.5% and 26.1% in 2013, respectively. Hyperproduction of KOXY enzyme in Klebsiella oxytoca remained below 9.5% and did not show an increasing trend. The overall increase in the proportions of isolates-producing ESBLAin E. coli/K. pneumoniae and hyperproduction of AmpC in Enterobacter/Citrobacter necessitates measures to hinder the spread of resistant bacteria and vigilant antibiotic stewardship.
authors.affiliation: Department of Microbiology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Haima
authors.initials: H
authors.lastname: Mylvaganam
authors.affiliation: Department of Microbiology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Helge
authors.initials: H
authors.lastname: Kolstad
authors.affiliation: Department of Microbiology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Rebecca Irene
authors.initials: RI
authors.lastname: Breistein
authors.affiliation: Department of Microbiology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Grete
authors.initials: G
authors.lastname: Lind
authors.affiliation: Department of Microbiology, Haukeland University Hospital, Bergen, Norway.|Department of Clinical Science, University of Bergen, Bergen, Norway.
authors.forename: Dag Harald
authors.initials: DH
authors.lastname: Skutlaberg
mesh_terms: D018550:Cephalosporin Resistance; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000453:epidemiology* / Q000382:microbiology*; D062665:Epidemiological Monitoring; D009664:Norway / Q000453:epidemiology; D010957:Plasmids / Q000032:analysis; D015995:Prevalence; D011446:Prospective Studies
keywords: 
  Enterobacteriaceae
  ; Ambler class C; Norway; Resistance; extended spectrum β-lactamases