Effect of subminimal inhibitory concentrations of gentamicin, penicillin, trimethoprim-sulfamethoxazole on adherence of uropathogenic Escherichia coli strains.

Evaluating the adherence factor of uropathogenic Escherichia coli is important for assessing the relative efficiency of antimicrobials when used at sub-minimal inhibitory concentration (sub-MICs). The microdilution method was used to determine the MICs of gentamicin, trimethoprim-sulfamethaxozole and penicillin. Then the efficacy of antimicrobial sub-MICs was determined by hemagglutination and adherence assays. Instead of showing nearly the same MICs, gentamicin had nearly twice the activity of trimethoprim-sulfamethaxozole. Gentamicin, as a "long acting" agent, can be accepted as being more effective than trimethoprim-sulfamethaxozole or penicillin, especially at sub-MICs, against adherence factors of uropathogenic E. coli, and can be used as monotherapy for urinary tract infections.