title: Molecular analysis of ciprofloxacin resistance and clonal relatedness of clinical Escherichia coli isolates from haematology patients receiving ciprofloxacin prophylaxis.
abstract: OBJECTIVE
  Widespread use of fluoroquinolones has led to increased levels of resistance in clinical isolates of Escherichia coli. We investigated the evolution of ciprofloxacin susceptibility and molecular epidemiology of clinical E. coli isolates in haematology patients receiving ciprofloxacin prophylaxis on the population and individual patient level.
  
  
  METHODS
  From August 2006 through December 2007 we collected all E. coli isolates (n = 404) from surveillance and infection-site cultures from 169 haematology patients receiving ciprofloxacin prophylaxis. Analysis of the gyrase A (gyrA) gene was performed by denaturing gradient gel electrophoresis (DGGE) in 364 isolates and clonal relatedness was determined by the single-enzyme amplified fragment length polymorphism (seAFLP) technique in 162 isolates. One hundred of these isolates were also subjected to qnrA analysis.
  
  
  RESULTS
  The average number of samples per patient was 2.4 (maximum 20) and 122 (30%) of 404 E. coli isolates were resistant to ciprofloxacin. In 124 patients only ciprofloxacin-susceptible strains were detected. DGGE revealed 11 different gyrA sequence patterns and, based on AFLP analysis, there was evidence of selection of ciprofloxacin-resistant strains under antibiotic pressure, as well as the occurrence of genetically indistinguishable ciprofloxacin-resistant and -susceptible E. coli isolates within one patient. Clonal dissemination of ciprofloxacin-resistant E. coli was observed, but did not predominate.
  
  
  CONCLUSIONS
  The genetic evolution of clinical E. coli isolates in haematology patients receiving ciprofloxacin prophylaxis is characterized by selection of ciprofloxacin-resistant strains. However, we did find evidence for de novo resistance mutation in ciprofloxacin-susceptible E. coli in individual patients under selective pressure.
authors.affiliation: Department of Medical Microbiology and Immunology, St Antonius Hospital, Postbus 2500, 3430 EM Nieuwegein, The Netherlands. bcvanhees@hotmail.com
authors.forename: Babette C
authors.initials: BC
authors.lastname: van Hees
authors.forename: Matthijs
authors.initials: M
authors.lastname: Tersmette
authors.forename: Rob J L
authors.initials: RJ
authors.lastname: Willems
authors.forename: Ben
authors.initials: B
authors.lastname: de Jong
authors.forename: Douwe
authors.initials: D
authors.lastname: Biesma
authors.forename: Erik J
authors.initials: EJ
authors.lastname: van Hannen
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use*; D019072:Antibiotic Prophylaxis / Q000379:methods*; D002939:Ciprofloxacin / Q000494:pharmacology / Q000627:therapeutic use*; D016000:Cluster Analysis; D027081:DNA Gyrase; D004269:DNA, Bacterial / Q000235:genetics; D058645:Denaturing Gradient Gel Electrophoresis; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000517:prevention & control*; D005838:Genotype; D019337:Hematologic Neoplasms / Q000150:complications; D006801:Humans; D017720:Molecular Epidemiology; D058889:Molecular Typing; D012150:Polymorphism, Restriction Fragment Length
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D002939:Ciprofloxacin; D027081:DNA Gyrase