title: Molecular characterisation of acquired and overproduced chromosomal blaAmpC in Escherichia coli clinical isolates.
abstract: Escherichia coli recovered from three hospitals in Barcelona (Spain) were studied to determine the prevalence of isolates with acquired AmpC (ac-AmpC) and/or overproduced chromosomal AmpC (c-AmpC). Mechanisms involved in blac-AmpC overexpression, blaac-AmpC and the plasmids associated with their distribution as well as the prevalence of plasmid-mediated quinolone resistance (PMQR) in AmpC-producing isolates were also determined. Isolates were selected according to their resistance phenotype. blaac-AmpC, alterations in the blac-AmpC promoter/attenuator, and PMQR genes [qnrA, qnrB, qnrS, aac(6')-Ib-cr and qepA] were characterised by PCR and sequencing. blac-AmpC expression was determined by qRT-PCR. Population structure analysis was performed using PFGE, MLST and phylogenetic group PCR. Plasmids carrying blaac-AmpC were characterised by PCR-based replicon typing and S1-PFGE. IncI1 and IncF plasmids were also analysed by plasmid MLST and replicon sequence typing, respectively. Among 21563 E. coli isolates, 240 (1.1%) overproduced AmpC β-lactamases, including 180 (75.0%) harbouring ac-AmpC (132 CMY-2 variants and 48 DHA-1) and 60 (25.0%) c-AmpC enzymes. Three mutation profiles in the blac-AmpC promoter/attenuator were associated with a 72.5-, 19.9- and 5.8-fold increased expression, respectively. Moreover, 63.3% of ac-AmpC and 43.3% of c-AmpC isolates belonged to B2, D, E or F phylogenetic groups. PMQR was found in 31% of ac-AmpC isolates [38 qnrB4, 8 aac(6')-Ib-cr, 6 qnrS1 and 3 qnrB19] and in 10% of c-AmpC isolates [5 aac(6')-Ib-cr and 1 qnrS1]. IncI1-ST12 and IncF were associated with blaCMY-2 and blaDHA-1, respectively. These results suggest that ac-AmpC β-lactamases were the main mechanism of AmpC production. Isolates and plasmids both showed high genetic diversity.
authors.affiliation: Hospital de la Santa Creu i Sant Pau and Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain; Universitat Autònoma de Barcelona, Barcelona, Spain; La Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Noemí
authors.initials: N
authors.lastname: Alonso
authors.affiliation: Hospital de la Santa Creu i Sant Pau and Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain; La Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Elisenda
authors.initials: E
authors.lastname: Miró
authors.affiliation: Hospital Universitari MútuaTerrassa, Barcelona, Spain.
authors.forename: Vanesa
authors.initials: V
authors.lastname: Pascual
authors.affiliation: Hospital de la Santa Creu i Sant Pau and Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain.
authors.forename: Alba
authors.initials: A
authors.lastname: Rivera
authors.affiliation: CatLab, Barcelona, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Simó
authors.affiliation: Consorci Sanitari de Terrassa, Barcelona, Spain.
authors.forename: Maria Consol
authors.initials: MC
authors.lastname: Garcia
authors.affiliation: CatLab, Barcelona, Spain.
authors.forename: Mariona
authors.initials: M
authors.lastname: Xercavins
authors.affiliation: CatLab, Barcelona, Spain.
authors.forename: Maria Antonia
authors.initials: MA
authors.lastname: Morera
authors.affiliation: Consorci Sanitari de Terrassa, Barcelona, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Espejo
authors.affiliation: Hospital de la Santa Creu i Sant Pau and Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain; Universitat Autònoma de Barcelona, Barcelona, Spain; La Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Mercè
authors.initials: M
authors.lastname: Gurguí
authors.affiliation: CatLab, Barcelona, Spain.
authors.forename: Josefa
authors.initials: J
authors.lastname: Pérez
authors.affiliation: Hospital Universitari MútuaTerrassa, Barcelona, Spain.
authors.forename: Mònica
authors.initials: M
authors.lastname: Rodríguez-Carballeira
authors.affiliation: Hospital Universitari MútuaTerrassa, Barcelona, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Garau
authors.affiliation: Hospital Universitari MútuaTerrassa, Barcelona, Spain; Universitat Internacional de Catalunya, Barcelona, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Calbo
authors.affiliation: Hospital de la Santa Creu i Sant Pau and Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain; Universitat Autònoma de Barcelona, Barcelona, Spain; La Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain. Electronic address: fnavarror@santpau.cat.
authors.forename: Ferran
authors.initials: F
authors.lastname: Navarro
authors.affiliation: Hospital de la Santa Creu i Sant Pau and Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain; Universitat Autònoma de Barcelona, Barcelona, Spain; La Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Mirelis
authors.affiliation: Hospital de la Santa Creu i Sant Pau and Institut d'Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain; Universitat Autònoma de Barcelona, Barcelona, Spain; La Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Pere
authors.initials: P
authors.lastname: Coll
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D002876:Chromosomes, Bacterial; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification / Q000201:enzymology* / Q000235:genetics*; D004927:Escherichia coli Infections / Q000382:microbiology*; D015870:Gene Expression; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D014644:Genetic Variation; D006801:Humans; D058885:Multilocus Sequence Typing; D009154:Mutation; D010957:Plasmids; D016133:Polymerase Chain Reaction; D015363:Quinolones / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013030:Spain; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D015363:Quinolones; C048795:AmpC beta-lactamases; D001618:beta-Lactamases
keywords: AmpC promoter; Antimicrobial resistance; Cephalosporins; PMQR; pMLST