Ciprofloxacin (Cipro) is more effective than amoxicillin-clavulanate (Augmentin) as a treatment for bladder infections in women, even when the microbe is susceptible to the latter drug, according to a report in the Journal of the American Medical Association.

Currently, the standard treatment for bladder infections or cystitis is trimethoprim-sulfamethoxazole (Bactrim), but emerging resistance to this agent has led to greater use of “fluoroquinolone” drugs, such as ciprofloxacin. In an effort to maintain the usefulness of this drug class, however, there has been a push to use non-fluoroquinolone antibiotics.

Despite increasing use of amoxicillin-clavulanate for cystitis, few studies have assessed the effectiveness of this treatment, according to Dr. Thomas M. Hooton of Harborview Medical Center in Seattle, and colleagues.

To investigate, the researchers assessed cure rates in 370 women with cystitis who were randomly selected to receive a 3-day course of ciprofloxacin or amoxicillin-clavulanate.

Cure was achieved in 77 percent of ciprofloxacin-treated women compared with just 58 percent of amoxicillin-clavulanate-treated women. Moreover, even when the analysis was confined to women infected with bacteria susceptible to amoxicillin-clavulanate, ciprofloxacin still provided a higher cure rate.

The authors believe that ciprofloxacin may have worked better than amoxicillin-clavulanate because of eradication of E. coli bacteria in the vagina. At 2-week follow-up, 45 percent of women treated with amoxicillin-clavulanate had vaginal E. coli compared with just 10 percent of women treated with ciprofloxacin.

The results, the investigators conclude, suggest that amoxicillin-clavulanate should only be considered as a treatment for cystitis when “use of other first- and second-line antibiotics is not feasible.”

SOURCE: Journal of the American Medical Association, February 23, 2005.