Risk factors for acquisition of urinary tract infections caused by ciprofloxacin resistant Escherichia coli.

From January 1990 to December 1992, ciprofloxacin resistant Escherichia coli was isolated in 125 of 1,946 urine cultures (6.4%) with more than 10(5) colony-forming units per ml. To determine the risk factors for acquisition of urinary tract infections caused by ciprofloxacin resistant E. coli a retrospective chart review was done. Data from 54 patients with urinary tract infections caused by ciprofloxacin resistant E. coli were compared with 51 controls matched by temporal occurrence and randomly selected among 540 patients with urinary tract infections caused by ciprofloxacin susceptible E. coli. Patients had greater proportions of asymptomatic bacteriuria or lower urinary tract symptoms (85% versus 61%, p = 0.01) and of relapse (22% versus 0%, p = 0.001) than controls. Urinary tract abnormalities (odds ratio 7.98, 95% confidence interval 2.7 to 3.1, p < 0.001), patient age 65 years or older (odds ratio 6.48, 95% confidence interval 2.2 to 19.1, p < 0.001), previous treatment with quinolones (odds ratio 19.09, 95% confidence interval 2.2 to 166.5, p = 0.008) and urinary catheterization (odds ratio 2.92, 95% confidence interval 1.1 to 8.5, p = 0.048) were independently associated with infections caused by ciprofloxacin resistant strains. Our results suggest that patients with urological abnormalities previously treated with quinolones are especially prone to urinary tract infection caused by ciprofloxacin resistant strains.