Ciprofloxacin treatment of urinary infections results in increased resistance of urinary E. coli to ciprofloxacin and co-trimoxazole.

Between 2000 and 2006 the sum of ciprofloxacin and folic acid antagonists prescriptions to Bavarian (South-eastern Gemany) outpatients stayed constant. However, prescription numbers of ciprofloxacin increased while those of folic acid antagonists decreased suggesting an apparent shift in the treatment of urinary infections toward ciprofloxacin. During the observation period the proportion of E. coli resistant against ciprofloxacin increased from 5% to 10% while that against co-trimoxazole increased from 21% to 27%. The proportion of E. coli simultaneously exhibiting resistance to ciprofloxacin and co-trimoxazole increased from 3.9% to 8.5%. A leading influence of ciprofloxacin application for these developments is discussed.