title: Mutant prevention concentrations of ciprofloxacin against urinary isolates of Escherichia coli and Klebsiella pneumoniae.
abstract: BACKGROUND
  The aim of this work was to study the ability of ciprofloxacin to restrict the development of resistant mutants of Escherichia coli and Klebsiella pneumoniae through determination of the Mutant Prevention Concentration (MPC).
  
  
  METHODS
  We studied 140 strains of E. coli and 86 strains of K. pneumoniae with different profiles of sensitivity to fluoroquinolones and extended spectrum beta lactamase (ESBL) production. The MPCs were determined using an inoculum of 1010 CFU/ml in Mueller-Hinton agar plates with serial concentrations of ciprofloxacin.
  
  
  RESULTS
  Ciprofloxacin-susceptible ESBL-producing strains showed a higher MPC for ciprofloxacin (P <0.001) than ciprofloxacin-susceptible non ESBL-producing strains, while ciprofloxacin-resistant ESBL-producing and non ESBL-producing strains did not significantly differ. The presence of qnr variants was associated with elevated MPCs. This was observed for both tested organisms.
  
  
  CONCLUSIONS
  Our study helps to explain the frequent finding of resistance to fluoroquinolones in ESBL-producing strains. Consequently, the use of concentrations of ciprofloxacin higher than the MIC in order to prevent the recovery and growth of resistant mutants is recommended.
authors: University of Balamand, Tripoli, Lebanon. ziad.daoud@balamand.edu.lb.
authors: Ziad
authors: Z
authors: Daoud
authors: Elie Salem
authors: ES
authors: Sokhn
authors: Eid
authors: E
authors: Azar
authors: Khalil
authors: K
authors: Masri
authors: Shira
authors: S
authors: Doron
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D002939:Ciprofloxacin / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics; D024841:Fluoroquinolones / Q000494:pharmacology; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D009154:Mutation; D014552:Urinary Tract Infections / Q000188:drug therapy / Q000382:microbiology*; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D024841:Fluoroquinolones; C485384:Qnr protein, E coli; C485385:Qnr protein, Klebsiella pneumoniae; D002939:Ciprofloxacin; D001618:beta-Lactamases