Context Guidelines for the management of acute uncomplicated
cystitis in women that recommend empirical therapy in
properly selected patients rely on the predictability of the agents
causing cystitis and knowledge of their antimicrobial susceptibility
Objective To assess the prevalence of and trends in antimicrobial
resistance among uropathogens causing well-defined episodes of acute
uncomplicated cystitis in a large population of women.
Design Cross-sectional survey of antimicrobial susceptibilities of
urine isolates collected during a 5-year period (January, May, and
Setting Health maintenance organization.
Patients Women aged 18 to 50 years with an outpatient diagnosis of
Main Outcome Measures Proportion of uropathogens demonstrating in
vitro resistance to selected antimicrobials; trends in resistance over
the 5-year study period.
Results Escherichia coli and Staphylococcus
saprophyticus were the most common uropathogens, accounting for
90% of the 4342 urine isolates studied. The prevalence of resistance
among E coli and all isolates combined was more than 20% for
ampicillin, cephalothin, and sulfamethoxazole in each year studied. The
prevalence of resistance to trimethoprim and
trimethoprim-sulfamethoxazole rose from more than 9% in 1992 to more
than 18% in 1996 among E coli, and from 8% to 16% among all
isolates combined. There was a statistically significant increasing
linear trend in the prevalence of resistance from 1992 to 1996
amongE coli and all isolates combined to ampicillin
(P<.002), and to cephalothin, trimethoprim, and
trimethoprim-sulfamethoxazole (P<.001). In contrast, the
prevalence of resistance to nitrofurantoin, gentamicin, and
ciprofloxacin hydrochloride was 0% to 2% among E coli and
less than 10% among all isolates combined, and did not change
significantly during the 5-year period.
Conclusions While the prevalence of resistance to
trimethoprim-sulfamethoxazole, ampicillin, and cephalothin increased
significantly among uropathogens causing acute cystitis, resistance to
nitrofurantoin and ciprofloxacin remained infrequent. These in vitro
susceptibility patterns should be considered along with other factors,
such as efficacy, cost, and cost-effectiveness in selecting empirical
therapy for acute uncomplicated cystitis in women.