title: Carbapenem-resistance mechanisms of multidrug-resistant Pseudomonas aeruginosa.
abstract: Clonal dissemination of multidrug-resistant Pseudomonas aeruginosa (MDRPA) is a major concern worldwide. The aim of this study was to explore the mechanisms leading to the carbapenem resistance of an MDRPA clone. Isolates were obtained from a surgical wound, sputum, urine and a blood culture. Pulsed-field gel electrophoresis (PFGE) showed high genomic homogeneity of these isolates and confirmed the circulation of an endemic clone belonging to serotype O4. Outer membrane protein (OMP) bands were visualized by SDS-PAGE, meropenem accumulation was measured in a bioassay and integrons were detected by PCR. Efflux pumps were studied for several antimicrobial agents and synergic combinations thereof in the presence or absence of both carbonyl cyanide m-chlorophenylhydrazone (CCCP) and Phe-Arg-β-naphthylamide (PAβN) at final concentrations of 10 and 40 mg l(-1), respectively. On OMP electrophoretic profiles, MDRPA showed a reduction of outer membrane porin D (OprD) and PCR demonstrated the presence of a class 1 integron with a cassette encoding aminoglycoside adenyltransferase B (aadB). Meropenem accumulation was slightly higher in bacilli than in the filamentous cells that formed in the presence of antibiotics. Overexpression of the efflux pump MexAB-OprM and a functional MexXY-OprM were detected in all isolates.
authors.affiliation: Laboratory of Molecular Microbiology and Antimicrobials, Department of Pathology and Experimental Therapeutics, University of Barcelona-IDIBELL, Campus de Bellvitge, L'Hospitalet, Barcelona.
authors.forename: Ester
authors.initials: E
authors.lastname: Fusté
authors.affiliation: Laboratory of Molecular Microbiology and Antimicrobials, Department of Pathology and Experimental Therapeutics, University of Barcelona-IDIBELL, Campus de Bellvitge, L'Hospitalet, Barcelona.
authors.forename: Lídia
authors.initials: L
authors.lastname: López-Jiménez
authors.affiliation: Laboratori de Referencia de Catalunya, Prat de Llobregat, Barcelona.
authors.forename: Concha
authors.initials: C
authors.lastname: Segura
authors.affiliation: Praxis Pharmaceuticals, Vitoria, Spain.
authors.forename: Eusebio
authors.initials: E
authors.lastname: Gainza
authors.affiliation: Laboratory of Molecular Microbiology and Antimicrobials, Department of Pathology and Experimental Therapeutics, University of Barcelona-IDIBELL, Campus de Bellvitge, L'Hospitalet, Barcelona.
authors.forename: Teresa
authors.initials: T
authors.lastname: Vinuesa
authors.affiliation: Laboratory of Molecular Microbiology and Antimicrobials, Department of Pathology and Experimental Therapeutics, University of Barcelona-IDIBELL, Campus de Bellvitge, L'Hospitalet, Barcelona.
authors.forename: Miguel
authors.initials: M
authors.lastname: Viñas
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D015780:Carbapenems / Q000494:pharmacology*; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D004151:Dipeptides / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial; D004357:Drug Synergism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D018272:Porins / Q000235:genetics / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D013845:Thienamycins / Q000494:pharmacology; D014031:Tobramycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D015780:Carbapenems; D004151:Dipeptides; D026901:Membrane Transport Proteins; C402791:MexXY protein, Pseudomonas aeruginosa; C402263:OprM protein, Pseudomonas aeruginosa; D018272:Porins; D013845:Thienamycins; C474925:phenylalanylarginine-naphthylamide; C077157:OprD protein, Pseudomonas aeruginosa; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000077731:Meropenem; D014031:Tobramycin