Emergence of ciprofloxacin resistance in Escherichia coli isolates from outpatient urine samples.

This study investigated the association between prescription of fluoroquinolones and emergence of ciprofloxacin resistance among Escherichia coli isolates in the urine of outpatients from whom a ciprofloxacin-sensitive E. coli strain had been isolated previously. Patients were identified and followed using the healthcare databases of Emilia-Romagna Region, Italy. The outcome of interest was the first isolation from urine of an E. coli strain resistant to ciprofloxacin. Prescription of fluoroquinolones during the previous 6 months was associated independently with the emergence of ciprofloxacin resistance; the strength of the association varied according to individual fluoroquinolone agents.