The prevalence of resistance among E. coli and all pathogens combined was more than 20 percent for ampicillin, cephalothin and sulfamethoxazole in each year studied. The prevalence of resistance to trimethoprim and trimethoprim-sulfamethoxazole rose from more than nine percent in 1992 to more than 18 percent in 1996 among E coli, and from eight percent to 16 percent among all isolates combined. In contrast, the prevalence of resistance to nitrofurantoin, gentamicin and ciprofloxacin hydrochloride was zero percent to two percent among E coli and less than 10 percent among all pathogens combined and did not change significantly during the five-year period. Of considerably greater concern is the increasing prevalence of resistance to trimethoprim and trimethoprim-sulfamethoxazole that we observed. These data suggest that trimethoprim and trimethoprim-sulfamethoxazole, which are now commonly used as first line regimens in the treatment of acute cystitis, may not be acceptable choices for empirical therapy for much longer.
Bacterial strains tend to develop resistance to antibiotics that are used frequently.
Thus, rates of resistance of bacteria to a particular antibiotic vary from community to community, depending on which antibiotics are commonly prescribed. The authors state that, in their view, when the prevalence of resistance to trimethoprim or trimethoprim-sulfamethoxazole among cystitis bacterial isolates exceeds 15 percent to 20 percent in a community, those antibiotic should not be used routinely to treat acute cystitis. They conclude that when physicians are choosing a therapy for patients with this type of urinary tract infection, antibiotic resistance must be considered in addition to other factors such as efficacy, adverse effects, cost and cost-effectiveness. The continued evolution of antimicrobial resistance among community-acquired isolates is worrisome and mandates both further surveillance and new approaches to slow the emergence of resistance. Any question regarding a medical diagnosis, treatment, referral, drug availability or pricing should be directed to either a licensed physician or to the product's manufacturer.