title: Evaluation of fluoroquinolone resistance mechanisms in Pseudomonas aeruginosa multidrug resistance clinical isolates.
abstract: Efflux transporters have a considerable role in the multidrug resistance (MDR) of Pseudomonas aeruginosa, an important nosocomial pathogen. In this study, 45 P. aeruginosa clinical strains, with an MDR phenotype, have been isolated in a hospital of Northern Italy and characterized to identify the mechanisms responsible for their fluoroquinolone (FQ) resistance. These isolates were analyzed for clonal similarity, mutations in genes encoding the FQ targets, overexpression of specific Resistance Nodulation-cell Division efflux pumps, and search for mutations in their regulatory genes. The achieved results suggested that the mutations in genes encoding ciprofloxacin targets represented the main mechanism of FQ resistance of these strains; 97.8% of these isolates showed mutations in gyrA, 28.9% in gyrB, 88.9% in parC, and 6.7% in parE. Another mechanism of resistance was overexpression of the efflux pumps in some representative strains. In particular, overexpression of MexXY-OprM drug transporter was found in five isolates, whereas overexpression of MexCD-OprJ was detected in two isolates; surprisingly, in one of these last two isolates, also overexpression of MexAB-OprM pump was identified.
authors.affiliation: Department of Genetics and Microbiology, University of Pavia, Pavia, Italy. mariarosalia.pasca@unipv.it
authors.forename: Maria Rosalia
authors.initials: MR
authors.lastname: Pasca
authors.forename: Claudia
authors.initials: C
authors.lastname: Dalla Valle
authors.forename: Ana Luisa
authors.initials: AL
authors.lastname: De Jesus Lopes Ribeiro
authors.forename: Silvia
authors.initials: S
authors.lastname: Buroni
authors.forename: Maria Cristiana
authors.initials: MC
authors.lastname: Papaleo
authors.forename: Silvia
authors.initials: S
authors.lastname: Bazzini
authors.forename: Claudia
authors.initials: C
authors.lastname: Udine
authors.forename: Maria Loreto
authors.initials: ML
authors.lastname: Incandela
authors.forename: Silvio
authors.initials: S
authors.lastname: Daffara
authors.forename: Renato
authors.initials: R
authors.lastname: Fani
authors.forename: Giovanna
authors.initials: G
authors.lastname: Riccardi
authors.forename: Piero
authors.initials: P
authors.lastname: Marone
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D027081:DNA Gyrase / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D024841:Fluoroquinolones / Q000494:pharmacology*; D015964:Gene Expression Regulation, Bacterial; D005809:Genes, Regulator; D006801:Humans; D026901:Membrane Transport Proteins / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D009154:Mutation; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D019105:Random Amplified Polymorphic DNA Technique
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D024841:Fluoroquinolones; D026901:Membrane Transport Proteins; D027081:DNA Gyrase