Impact of quinolone restriction on resistance patterns of Escherichia coli isolated from urine by culture in a community setting

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