title: Molecular characterization of multiresistant Escherichia coli producing or not extended-spectrum β-lactamases.
abstract: BACKGROUND
  The prevalence and type of plasmids, resistance genes and integrons carried by two collections of multiresistant E. coli producing or not extended-spectrum β-lactamases have been compared. Rep-PCR was used to determine the clonal relationship of the organisms. Plasmids were classified according to their incompatibility. Class 1 and Class 2 integrons and antibiotic resistance genes were analysed by PCR and sequencing.
  
  
  RESULTS
  Both collections of organisms contained a large diversity of unrelated strains with some clones distributed in both groups of isolates. Large plasmids were identified in the two groups of organisms. Plasmids with replicons repK and repColE were more frequent among ESBL-producing isolates, while repFIA, repFII and repA/C replicons were more frequent in isolates lacking ESBL. Conjugative plasmids with repK and repA/C replicons coded for CTX-M-14 and CMY-2 β-lactamases, respectively. No significant differences were observed in the distribution of class 1 and class 2 integrons among multiresistant E. coli producing or not ESBL, and dfrA17-ant(3")-Ie was the cassette arrangement most commonly found.
  
  
  CONCLUSIONS
  In the concrete temporal and geographical context of this study, multiresistant E. coli producing ESBL or other mechanisms of resistance were largely clonally diverse and present some differences in the types of harboured plasmids. Still, some clones were found in both ESBL-producing and -lacking isolates.
authors.affiliation: Service of Microbiology, Hospital Universitario Marqués de Valdecilla-IFIMAV, Av/ de Valdecilla s/n, Santander 39008, Spain. biolbelen@hotmail.com
authors.forename: Belén
authors.initials: B
authors.lastname: Ruiz del Castillo
authors.forename: Laura
authors.initials: L
authors.lastname: Vinué
authors.forename: Elena Jesús
authors.initials: EJ
authors.lastname: Román
authors.forename: Beatriz
authors.initials: B
authors.lastname: Guerra
authors.forename: Alessandra
authors.initials: A
authors.lastname: Carattoli
authors.forename: Carmen
authors.initials: C
authors.lastname: Torres
authors.forename: Luis
authors.initials: L
authors.lastname: Martínez-Martínez
mesh_terms: D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000145:classification / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology; D005798:Genes, Bacterial; D014644:Genetic Variation; D006801:Humans; D032023:Integrons; D010957:Plasmids; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D062211:Spatio-Temporal Analysis; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001618:beta-Lactamases