Sultamicillin versus trimethoprim/sulfamethoxazole in the treatment of urinary tract infections.

Sultamicillin, a novel compound in which ampicillin and the beta-lactamase inhibitor sulbactam are linked as a double ester, was compared with trimethoprim/sulfamethoxazole with regard to in vitro activity, therapeutic efficacy and safety in the treatment of UTIs. The MICs of ampicillin and ampicillin in combination with sulbactam (10 micrograms), trimethoprim and trimethoprim in combination with sulfamethoxazole (1:19) were determined for 400 isolates causing UTI using an agar dilution technique (multipointer, cfu = 10(4]. The organisms isolated consisted of about one-third E. coli, one-third other Gram-negative strains and one-third Gram-positive strains. About half of the Gram-positive strains were enterococci and the other half staphylococci. A concentration of 8 micrograms/ml ampicillin inhibited 76% of the isolates while ampicillin in combination with sulbactam inhibited 86%. A concentration of 4 micrograms/ml trimethoprim inhibited 77% of the isolates, while trimethoprim in combination with sulfamethoxazole inhibited 83%. In a prospectively randomized clinical trial, 38 patients with UTI were treated orally with either sultamicillin (375 mg) or trimethoprim/sulfamethoxazole (160 mg/800 mg) twice daily for 7 d. Sultamicillin eradicated bacteriuria during therapy and up to 1 to 2 weeks after therapy in 63% and trimethoprim/sulfamethoxazole in 50% of evaluable patients. Side effects were reported for 2 sultamicillin (gastric pain, diarrhea) and 2 trimethoprim/sulfamethoxazole patients (gastric pain, exanthema), with the latter 2 being withdrawn after 6 days of therapy. Sultamicillin appeared as effective and safe as trimethoprim/sulfamethoxazole in the treatment of UTI.