title: Characterization of carbapenem nonsusceptible Pseudomonas aeruginosa in Denmark: a nationwide, prospective study.
abstract: From January 1st 2011 through June 30th 2011, 116 nonreplicate, noncystic fibrosis-related Pseudomonas aeruginosa isolates with reduced carbapenem susceptibility were collected from 12 out of 13 Danish departments of clinical microbiology. The presence of acquired β-lactamases was assessed with combination tablet-diffusion methodology and polymerase chain reaction. In addition, antimicrobial susceptibility testing, an efflux pump inhibitor assay, and pulsed-field gel electrophoresis (PFGE) were performed. Isolates producing acquired β-lactamases were further investigated by serotyping and multi locus sequence typing. Eight isolates produced the metallo-β-lactamase (MBL) VIM-2, and one isolate produced OXA-10 and VEB-1-like extended-spectrum beta-lactamase (ESBL). Phenotypic indications of derepressed AmpC and efflux pump were seen in 56 and 43 isolates, respectively. Overall, the results indicate that mutational factors related to permeability--often combined with derepressed, chromosomal AmpC--is the main factor behind carbapenem nonsusceptibility in Danish P. aeruginosa isolates. The ESBL producer and all the VIM producers belonged to international clones. PFGE revealed that most of the isolates were unrelated, but clonal spread was seen; the 116 isolates distributed in 97 PFGE types, with the largest cluster consisting of 4 isolates (including three isolates from the same hospital with 100% similarity). Thirty-two isolates were pair-wise related, while the remaining isolates were clonally unrelated, as were all nine ESBL/MBL producers.
authors: 1 Statens Serum Institut , Copenhagen, Denmark .
authors: Frank
authors: F
authors: Hansen
authors: Helle Krogh
authors: HK
authors: Johansen
authors: Claus
authors: C
authors: Østergaard
authors: Magnus
authors: M
authors: Arpi
authors: Dennis Schrøder
authors: DS
authors: Hansen
authors: Pia
authors: P
authors: Littauer
authors: Anette
authors: A
authors: Holm
authors: Ole
authors: O
authors: Heltberg
authors: Helga
authors: H
authors: Schumacher
authors: Kurt
authors: K
authors: Fuursted
authors: Mari-Ann Domar
authors: MA
authors: Lykke
authors: Birgitte
authors: B
authors: Tønning
authors: Anette M
authors: AM
authors: Hammerum
authors: Ulrik Stenz
authors: US
authors: Justesen
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015780:Carbapenems / Q000494:pharmacology*; D003550:Cystic Fibrosis / Q000150:complications / Q000188:drug therapy / Q000382:microbiology; D003718:Denmark; D016521:Electrophoresis, Gel, Pulsed-Field; D015870:Gene Expression; D006801:Humans; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D011446:Prospective Studies; D011552:Pseudomonas Infections / Q000150:complications / Q000188:drug therapy / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D012703:Serotyping; D018440:beta-Lactam Resistance / Q000187:drug effects / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; C425107:beta-lactamase OXA-10; C055187:beta-lactamase PSE-2; C425108:beta-lactamase bla(vim-2); C048795:AmpC beta-lactamases; D001618:beta-Lactamases