title: Impact of quinolone restriction on resistance patterns of Escherichia coli isolated from urine by culture in a community setting.
abstract: BACKGROUND
  Decreased antimicrobial susceptibility after increased antibiotic use is a known phenomenon. Restoration of susceptibility once antimicrobial use is decreased is not self-evident. Our objective was to evaluate, in a community setting, the impact of quinolone restriction on the antimicrobial resistance of E. coli urine isolates.
  
  
  METHODS
  We conducted a retrospective, quasi-experimental ecological study to assess the proportion of quinolone-susceptible E. coli urine isolates in the periods before, during, and after a nationwide restriction on ciprofloxacin use was implemented. We used an interrupted time interval analysis for outcome evaluation.
  
  
  RESULTS
  We found a significant decline in quinolone consumption, measured as defined daily doses (DDDs) per month, between the preintervention and intervention periods (point estimate, -1827.3 DDDs per month; 95% confidence interval [CI], -2248.8 to -1405.9 DDDs per month; p < .001). This decline resulted in a significant decrease in E. coli nonsusceptibility to quinolones, from a mean of 12% in the preintervention period to a mean of 9% in the intervention period (odds ratio, 1.35; p = .014). The improved susceptibility pattern reversed immediately when quinolone consumption rose. Moreover, a highly significant inverse relationship was found between the level of quinolone use (regardless of intervention period) and the susceptibility of E. coli urine isolates to quinolone (odds ratio, 1.70; 95% CI, 1.26-2.28). During the months of highest quinolone use (8321 DDDs per month), the proportion of nonsusceptibility was 14%, whereas during the months of lowest quinolone use (4027 DDDs per month), the proportion of nonsusceptibility was 9%. An average decrease in resistance of 1.16% was observed for each decrease of 1000 DDDs.
  
  
  CONCLUSIONS
  Reducing quinolone consumption can lead to an immediate increase in the susceptibility of E. coli urine isolates to quinolones.
authors.affiliation: Infectious Diseases Unit, Meir Medical Center, Kfar Saba, Israel.
authors.forename: Bat Sheva
authors.initials: BS
authors.lastname: Gottesman
authors.forename: Yehuda
authors.initials: Y
authors.lastname: Carmeli
authors.forename: Pnina
authors.initials: P
authors.lastname: Shitrit
authors.forename: Michal
authors.initials: M
authors.lastname: Chowers
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D002939:Ciprofloxacin / Q000008:administration & dosage / Q000494:pharmacology*; D017714:Community-Acquired Infections / Q000188:drug therapy / Q000382:microbiology; D004305:Dose-Response Relationship, Drug; D024881:Drug Resistance, Bacterial / Q000187:drug effects; D004363:Drug Utilization / Q000706:statistics & numerical data; D004926:Escherichia coli / Q000187:drug effects* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000188:drug therapy* / Q000382:microbiology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007557:Israel; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D012189:Retrospective Studies; D014556:Urine / Q000382:microbiology*; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D002939:Ciprofloxacin