title: Reduced Susceptibility to Cefepime in Clinical Isolates of Enterobacteriaceae Producing OXA-1 Beta-Lactamase.
abstract: An increase of Enterobacteriaceae isolates with reduced susceptibility to cefepime (FEP) and amoxicillin/clavulanate (AMC) has been observed in our area. The aim of this study was to characterize this antibiotic resistance phenotype and its molecular epidemiology. A total of 33 Enterobacteriaceae strains were studied. blaOXA-1 genes and their genetic environment were analyzed by polymerase chain reaction (PCR) and sequencing. Plasmids were transferred by conjugation and/or transformation and classified using PCR-based inc/rep typing and IncF subtyping. Escherichia coli isolates were typed by phylogroup, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing. Outer membrane proteins were studied by sodium dodecylsulfate-polyacrylamide gel electrophoresis and expression of blaOXA-1 genes by reverse transcription-PCR. FEP minimum inhibitory concentration yielded values of 1-16 mg/L. Twenty-nine (87.9%) isolates produced OXA-1, of which 24 (82.7%) were located in class 1 integron, and 9 (27.3%) produced TEM-1. Among the 24 E. coli OXA-1-producers, PFGE revealed two main clusters: one belonged to C-ST88 and the other to B23-ST131. Thirteen plasmids containing blaOXA-1 were transferred, nine belonged to IncF replicon (4 F2:A1:B-, 2 F1:A1:B1, 1 F1:A2:B-, 1 F18:A2:B1, 1 F5:A-:B1) and four were nontypeable. In conclusion, reduced susceptibility to FEP was mostly due to OXA-1 beta-lactamase. In E. coli, this increase is mainly due to the dissemination of two clones, which have captured different IncF plasmids. Among non-E. coli strains, five isolates produced OXA-1 and one isolate produced only TEM-1.
authors: 1 Infectious Diseases and Clinical Microbiology Unit, University Hospital Virgen Macarena , Seville, Spain .
authors: Eva
authors: E
authors: Torres
authors: 1 Infectious Diseases and Clinical Microbiology Unit, University Hospital Virgen Macarena , Seville, Spain .|2 Department of Microbiology, University of Seville , Seville, Spain .
authors: Lorena
authors: L
authors: López-Cerero
authors: 2 Department of Microbiology, University of Seville , Seville, Spain .
authors: José Manuel
authors: JM
authors: Rodríguez-Martínez
authors: 1 Infectious Diseases and Clinical Microbiology Unit, University Hospital Virgen Macarena , Seville, Spain .|2 Department of Microbiology, University of Seville , Seville, Spain .
authors: Álvaro
authors: Á
authors: Pascual
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000077723:Cefepime; D002511:Cephalosporins / Q000494:pharmacology; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000188:drug therapy / Q000382:microbiology; D015870:Gene Expression; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013030:Spain; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D004269:DNA, Bacterial; D007527:Isoenzymes; D000077723:Cefepime; C039404:beta-lactamase OXA-2; D001618:beta-Lactamases