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Difference in quinolone resistance in Pseudomonas aeruginosa from cystic fibrosis and non-cystic fibrosis patients

Abstract number: p1266

Henrichfreise  B., Wiegand  I., Noll  I., Pfister  W., Wiedemann  B.

Objectives: 

German Network for Antimicrobial Resistance Surveillance (GENARS) data reveal for P. aeruginosa strains from cystic fibrosis patients (CFP) a higher rate but lower level of resistance to quinolones compared to strains from non-CF patients (nCFP). The aim of our study was to investigate this phenomenon on a molecular level.

Methods: 

76 CFP and 207 nCFP GENARS strains from Jan 2002 to Jun 2004 with reduced susceptibility to ciprofloxacin (CIP) were included. For 12 CFP and 10 nCFP strains the QRDR of gyrA and parC, mexR and nfxB were sequenced. Clonal relationship among those strains was precluded by PFGE and a PCR screening for qnr was carried out.

Results: 

In Table 1 the MIC distributions of CIP for CFP and nCFP strains are shown. In CFP strains MICs <= 4 mg/L were the most frequent, single mutations in gyrA predominated and no mutation in parC was found. Multiple mutations and a 4-fold higher rate of MICs >= 16 mg/L was found in nCFP strains. Qnr was not detected.

Conclusion: 

In several strains other mechanisms than the tested seem to contribute to CIP resistance. In CFP strains resistance to CIP was characterized by low-level resistance mostly due to single mutations in gyrA. In contrast, high-level resistance and multiple mutations were typically found in nCFP strains. Lower concentrations of quinolones in the mucus of the CF lung or biofilm formation may reduce the need for multiple mutations in CFP strains.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Subject:
Location: Oxford, UK
Presentation type:
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