title: Frequency of Plasmid-Mediated AmpC β-Lactamases in Escherichia coli Isolates from Urine Samples in São Paulo, Brazil.
abstract: Plasmid-mediated AmpC β-lactamases (PMACBLs) in Enterobacteriaceae encode resistance to third-generation cephalosporins, and these can mediate carbapenem resistance when associated with porin loss. However, no standardized phenotypic method is available for detecting these enzymes in the clinical microbiology laboratory. Limited data are available concerning the frequency of PMACBLs in Enterobacteriaceae in Brazil. This study was conducted in response to an increased cefoxitin (CFO) resistance rate of 3.7% in Escherichia coli isolates from urine samples from patients with suspected urinary tract infections during 2010. We collected 2,266 E. coli isolates prospectively during January 2012. A total of 109 (4.8%) isolates were nonsusceptible to CFO. These strains were further examined using multiplex PCR for the presence of genes encoding PMACBLs and using inhibitor assays with CFO and ceftazidime (CAZ) disks with and without phenylboronic acid. Pulsed-field gel electrophoresis was used to evaluate clonal dissemination. Genes encoding PMACBLs were detected in 1.8% of the isolates from inpatients and 0.46% of isolates from outpatients. The most prevalent gene was blaCMY-2 and blaCMY-4 was also detected. The phenotypic analysis showed 100% sensitivity and specificity for CMY-2 and CMY-4 when CFO-resistant isolates with a minimum zone diameter difference of 5 mm for CAZ or CAZ and CFO were considered positive. Although most of the isolates were nonclonal, one clonal group with two isolates was observed. Thus, the most frequent PMACBL in E. coli from São Paulo, Brazil is CMY-2, and both clonal and plasmid-mediated dissemination occur.
authors.affiliation: 1 Clinical Analysis and Toxicology Department, School of Pharmacy, University of São Paulo , São Paulo, Brazil .
authors.forename: Darlan Augusto Costa
authors.initials: DA
authors.lastname: Rocha
authors.affiliation: 1 Clinical Analysis and Toxicology Department, School of Pharmacy, University of São Paulo , São Paulo, Brazil .
authors.forename: Juliana Coutinho
authors.initials: JC
authors.lastname: Campos
authors.affiliation: 2 University Hospital, University of São Paulo , São Paulo, Brazil .
authors.forename: Lilian Ferri
authors.initials: LF
authors.lastname: Passadore
authors.affiliation: 3 Microbiology Department, Federal University of São Paulo , São Paulo, Brazil .
authors.forename: Suely Carlos Ferreira
authors.initials: SC
authors.lastname: Sampaio
authors.affiliation: 4 Department of Infectious and Parasitic Diseases, University of São Paulo , Medical School, São Paulo, Brazil .
authors.forename: Antonio Carlos
authors.initials: AC
authors.lastname: Nicodemo
authors.affiliation: 1 Clinical Analysis and Toxicology Department, School of Pharmacy, University of São Paulo , São Paulo, Brazil .|5 Fleury Diagnostic Medicine-Microbiology Section , São Paulo, Brazil .
authors.forename: Jorge Luiz Mello
authors.initials: JL
authors.lastname: Sampaio
mesh_terms: D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000145:classification / Q000235:genetics*; D001938:Brazil / Q000453:epidemiology; D002440:Cefoxitin / Q000494:pharmacology; D018550:Cephalosporin Resistance / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000652:urine; D005260:Female; D015870:Gene Expression; D022761:Gene Transfer, Horizontal; D006801:Humans; D015994:Incidence; D007297:Inpatients; D008297:Male; D017720:Molecular Epidemiology; D060885:Multiplex Polymerase Chain Reaction; D010045:Outpatients; D010802:Phylogeny; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism*; D014552:Urinary Tract Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology / Q000652:urine; D001618:beta-Lactamases / Q000145:classification / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002440:Cefoxitin; C048795:AmpC beta-lactamases; D001618:beta-Lactamases