Evaluation of fluoroquinolone resistance mechanisms in Pseudomonas aeruginosa multidrug resistance clinical isolates

Maria Rosalia Pasca, Claudia Dalla Valle, Ana Luisa De Jesus Lopes Ribeiro, Silvia Buroni, Maria Cristiana Papaleo, Silvia Bazzini, Claudia Udine, Maria Loreto Incandela, Silvio Daffara, Renato Fani, Giovanna Riccardi, Piero Marone

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Pages (from-to)23-32
Number of pages10
JournalMicrobial Drug Resistance
Issue number1
Publication statusPublished - Feb 1 2012

ASJC Scopus subject areas

  • Microbiology (medical)
  • Pharmacology
  • Immunology
  • Microbiology


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