Antibiotic failure in the treatment of urinary tract infections in young women.

Urinary tract infections (UTIs) are a common problem in young women. The aim of this study was to describe the pattern of antibiotic prescribing to young women presenting with new UTIs and to investigate the proportion who required further treatment if prescribed antibiotics. A secondary aim was to investigate whether the likelihood of treatment failure varied between different antibiotics and, in the case of trimethoprim (the antibiotic most frequently prescribed for UTIs) between prescriptions of different duration. The study included all women aged 15-44 years registered on the UK General Practice Research Database. All diagnoses of UTI or cystitis with an associated prescription for an antibiotic were identified. A further prescription of an antibiotic within 28 days was taken to indicate failure of the initial treatment. Overall, 14% of 75045 newly treated patients with UTI received a second antibiotic within 28 days. Older women, aged 35-44, pregnant patients and those with diabetes were significantly more likely to require further treatment. With trimethoprim as the reference antibiotic, after 28 days patients prescribed amoxicillin were significantly more likely to require a second course of antibiotics. Those prescribed co-trimoxazole were significantly less likely to require further treatment. In each case the difference in failure rate was small and may be of little clinical significance. There was no significant difference between trimethoprim and nitrofurantoin, norfloxacin, ciprofloxacin or the cephalosporins. Three-day prescriptions for trimethoprim appeared as effective as those for 5 or 7 days. This study gives some observational evidence of the effectiveness of antibiotic prescribing in young women with UTIs and shows that between 12% and 16% of patients will return within 28 days for further treatment, irrespective of the antibiotic prescribed initially.