title: Characterization of carbapenem resistance mechanisms and integrons in Pseudomonas aeruginosa strains from blood samples in a French hospital.
abstract: Metallo-β-lactamases (MBLs), porin OprD, integrons, virulence factors and the clonal relationships were characterized in imipenem-resistant Pseudomonas aeruginosa (IRPA) isolates. Fifty-six IRPA strains were recovered from blood samples of different patients at a Toulouse teaching hospital from 2011 to 2013. Susceptibility testing of 14 antibiotics was performed by the disc diffusion method. Detection and characterization of MBLs, the oprD gene and integrons were studied by PCR and sequencing. Thirteen genes involved in the virulence of P. aeruginosa were analysed. Molecular typing of IRPA strains was performed by PFGE and multilocus sequence typing. In this study, 61 % of the IRPA isolates showed a multi-resistance phenotype. The MBL phenotype, detected in three isolates (5.4 %), was linked to the blaVIM-2 gene. The oprD gene was amplified in 55 (98.2 %) IRPA strains, and variations were observed in 54 of them. Insertion sequences (IS) truncating oprD were detected in eight IRPA strains, with the novel ISPa56 identified in two strains. Class 1 integrons were detected in 24 (42.9 %) IRPA strains. The blaVIM-2 gene was found inside the class 1 integron arrangements. The new integrons In1054 (intI1-aacA56-qacEΔ1-sul1) and In1160 (intI1-aacA4-aacC1d-ISKpn4-gcuE-qacEΔ1-sul1) have been described for the first time, to the best of our knowledge, in this study. A high clonal diversity was found in our strains. Among the variety of sequence types (STs) found, ST175, ST233, ST235, ST244 and ST654 were noteworthy as epidemic clones. In conclusion, 5.4 % of IRPA strains showed an MBL phenotype linked to the blaVIM-2 gene. The identified oprD high polymorphism could be implicated in the variable resistance to carbapenems in IRPA strains. The dissemination of high-risk clones is a cause of concern.
authors.affiliation: Centro de Investigación Biomédica de La Rioja (CIBIR), Área de Microbiología Molecular, Logroño, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Rojo-Bezares
authors.affiliation: CHU Toulouse, Hôpital Purpan, Service de Bactériologie-Hygiène, Toulouse, France.|Centre de Physiopathologie de Toulouse Purpan (CPTP), Inserm UMR1043 - CNRS UMR5282 - INRA USC1360, Université Toulouse III, Toulouse, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Cavalié
authors.affiliation: CHU Toulouse, Hôpital Purpan, Service de Bactériologie-Hygiène, Toulouse, France.|Centre de Physiopathologie de Toulouse Purpan (CPTP), Inserm UMR1043 - CNRS UMR5282 - INRA USC1360, Université Toulouse III, Toulouse, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Dubois
authors.affiliation: CHU Toulouse, Hôpital Purpan, Service de Bactériologie-Hygiène, Toulouse, France.|Centre de Physiopathologie de Toulouse Purpan (CPTP), Inserm UMR1043 - CNRS UMR5282 - INRA USC1360, Université Toulouse III, Toulouse, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Oswald
authors.affiliation: Centro de Investigación Biomédica de La Rioja (CIBIR), Área de Microbiología Molecular, Logroño, Spain.|Universidad de La Rioja, Área de Bioquímica y Biología Molecular, Logroño, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Torres
authors.affiliation: Centro de Investigación Biomédica de La Rioja (CIBIR), Área de Microbiología Molecular, Logroño, Spain.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Sáenz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015780:Carbapenems / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D005260:Female; D005602:France / Q000453:epidemiology; D006784:Hospitals, Teaching; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D032023:Integrons; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D058885:Multilocus Sequence Typing; D016133:Polymerase Chain Reaction; D018272:Porins / Q000235:genetics; D011552:Pseudomonas Infections / Q000453:epidemiology / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D037521:Virulence Factors / Q000235:genetics*; D055815:Young Adult; D018440:beta-Lactam Resistance / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D018272:Porins; D037521:Virulence Factors; C077157:OprD protein, Pseudomonas aeruginosa