Risk factors for urinary tract infections due to ciprofloxacin-resistant Escherichia coli in a tertiary care urology department in Switzerland.

QUESTIONS UNDER STUDY: Monitoring of antimicrobial resistance is a key component of antibiotic stewardship programs. In 2007, a significantly higher resistance rate of Escherichia coli to ciprofloxacin was found at the Department of Urology, University Hospital Zurich, Switzerland, when compared to other hospital units. Thus, we aimed to determine the risk factors for this increased fluoroquinolone resistance in outpatients and inpatients with urinary tract infection (UTI) or colonisation with E. coli.

METHODS: We performed a cross sectional study including 275 patients of the Department of Urology in whom E. coli was isolated from urine or blood cultures between 01.01.2006 and 31.08.2007. Clinical data were collected from patients' records using a structured questionnaire. Multivariable analysis was performed for the detection of risk factors.

RESULTS: Ciprofloxacin-resistant E. coli was detected in 22% of patients. Risk factors for ciprofloxacin-resistant E. coli included prior use of fluoroquinolones (odds ratio [OR] (95% confidence intervals): 2.24 (1.08-4.62), p = 0.030), prior urinary tract catheterisation (OR: 2.41 (1.02-5.67), p = 0.044) and recurrent UTIs (OR: 2.26 (1.07-4.78), p = 0.032). 60.8% of all prescriptions in urinary tract infections were for fluoroquinolones, and this antibiotic class was the empiric antibiotic regimen of choice in 72.5% of all acute, uncomplicated, urinary tract infections.

CONCLUSIONS: The increasing prevalence of ciprofloxacin-resistant E. coli makes empiric therapy in UTIs with this agent questionable, especially in patients with one or several of the above mentioned risk factors. Due to the increasing resistance rate, continuous surveillance and susceptibility testing in individual patients, particularly with complicated UTIs, is indispensable for adequate therapy.