Study examines three-day antibiotic regimens for treating bladder infection in women


CHICAGO A three-day regimen of the antibiotic amoxicillin-clavulanate is not as effective as ciprofloxacin at treating an uncomplicated bladder infection in women, according to a study in the February 23 issue of JAMA.

Acute uncomplicated urinary tract infections (UTIs) are among the most commonly encountered bacterial infections in women, according to background information in the article. Management of these infections has been made more complicated in recent years by increasing antimicrobial resistance, which has led to increased use of alternative antibiotics. There have been no published studies on the efficacy of one such antibiotic, amoxicillin-clavulanate, in the treatment of acute cystitis (inflammation of the urinary bladder) in the current era of high-level amoxicillin resistance.

Thomas M. Hooton, M.D., of the University of Washington and Harborview Medical Center, Seattle, and colleagues conducted a randomized trial that compared 3-day regimens of amoxicillin-clavulanate and ciprofloxacin for treatment of women with acute uncomplicated cystitis and used follow-up to evaluate the women for recurrent infection. Ciprofloxacin is in the fluoroquinolone class of antibiotics, a potent and frequently prescribed group that has shown increasing resistance. The trial included 370 women, aged 18 to 45 years. Subjects were randomly assigned to receive amoxicillin-clavulanate (500 mg/125 mg twice daily) or ciprofloxacin (250 mg twice daily) for 3 days and were followed for 4 months.

The researchers found that clinical cure resolution of the symptoms associated with UTI was observed in 93 (58 percent) of 160 women treated with amoxicillin-clavulanate compared with 124 (77 percent) of 162 women treated with ciprofloxacin. Amoxicillin-clavulanate was not as effective as ciprofloxacin even among women infected with bacterial strains susceptible to amoxicillin-clavulanate (65 [60 percent] of 109 women in the amoxicillin-clavulanate group vs. 114 [77 percent] of 149 women in the ciprofloxacin group. The difference in clinical cure rates occurred almost entirely within the first 2 weeks after therapy. Microbiological cure (determine by follow-up urine culture) at 2 weeks was observed in 118 (76 percent) of 156 women treated with amoxicillin-clavulanate compared with 153 (95 percent) of 161 women treated with ciprofloxacin.

"Trimethoprim-sulfamethoxazole should continue to be the first-line treatment for acute cystitis if the woman has no history of allergy to the drug and if the likelihood of trimethoprim-sulfamethoxazole resistance is low. In areas where the likelihood of trimethoprim-sulfamethoxazole resistance is high (greater than 20 percent) or in women who have risk factors for trimethoprim-sulfamethoxazole resistance, nitrofurantoin or a fluoroquinolone [ciprofloxacin] is an appropriate choice. Amoxicillin-clavulanate in a 3-day regimen is not as effective as a fluoroquinolone for the treatment of acute uncomplicated cystitis, even in those women with UTIs caused by susceptible uropathogens, and should be considered only when use of other first- and second-line antibiotics is not feasible," the authors write.

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Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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