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

Bat Sheva Gottesman, Yehuda Carmeli, Pnina Shitrit, Michal Chowers

Research output: Contribution to journalArticlepeer-review

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. Conclusion. Reducing quinolone consumption can lead to an immediate increase in the susceptibility of E. coli urine isolates to quinolones.

Original languageEnglish
Pages (from-to)869-875
Number of pages7
JournalClinical Infectious Diseases
Volume49
Issue number6
DOIs
StatePublished - 15 Sep 2009

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