title: Beta-lactamase characterization in Escherichia coli isolates with diminished susceptibility or resistance to extended-spectrum cephalosporins recovered from sick animals in Spain.
abstract: A total of 1439 Escherichia coli isolates from sick animals were received from the Spanish Network of Veterinary Antimicrobial Resistance Surveillance (VAV) from 1997 to 2001. Antimicrobial susceptibility tests were performed and diminished susceptibility to cefotaxime and ceftazidime was identified in 2.5% and 2.8% of the isolates, respectively. Beta-lactamase characterization was carried out in the group of 20 E. coli isolates with both characteristics. The MIC ranges of different beta-lactams showed by these 20 isolates were as follows (in microg/ml): ampicillin (64-->256), amoxicillin-clavulanic acid (4-64), ticarcillin (8-->128), cefazolin (32-->256), cefoxitin (4-->128), cefotaxime (1-64), ceftazidime (2-->64), ceftriaxone (0.5-64), imipenem (< or = 0.06-0.25), and aztreonam (2-->32). TEM, SHV, CMY, and FOX beta-lactamase genes were analyzed by PCR and sequencing. The beta-lactamase genes detected were the following ones (number of isolates): bla(TEM-1b) (3), bla(TEM-1a) (1), bla(TEM-30f) (2), bla(TEM-1b) + bla(CMY-2) (2), and bla(SHV-12) (1). Sequences of the promoter and/or attenuator region of the chromosomal ampC gene were studied in all the 20 isolates. Mutations at position -42 or -32 were detected in 16 isolates and these mutations were associated with the presence of a TEM type beta-lactamase in 6 isolates. Besides, a high variety of plasmidic beta-lactamases was detected including TEM-30 and CMY-2. To our knowledge, this is the first time that TEM-30 beta-lactamase has been detected in E. coli isolates of animal origin.
authors.affiliation: Area de Bioquímica y Biología Molecular, Universidad de La Rioja, 26006 Logroño, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Briñas
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Moreno
authors.forename: Tirushet
authors.initials: T
authors.lastname: Teshager
authors.forename: Myriam
authors.initials: M
authors.lastname: Zarazaga
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Sáenz
authors.forename: Concepción
authors.initials: C
authors.lastname: Porrero
authors.forename: Lucas
authors.initials: L
authors.lastname: Dominguez
authors.forename: Carmen
authors.initials: C
authors.lastname: Torres
mesh_terms: D000820:Animal Diseases / Q000453:epidemiology / Q000382:microbiology*; D000818:Animals; D018550:Cephalosporin Resistance / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics*; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology* / Q000662:veterinary*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013030:Spain / Q000453:epidemiology; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001618:beta-Lactamases