Cefaclor versus ampicillin for outpatient treatment of urinary tract infections.

An unblinded, randomized, prospective clinical trial of cefaclor, 250 mg twice daily, versus ampicillin, 500 mg four times daily, for a total of ten days of therapy, was conducted with 100 patients presenting to an emergency department with signs, symptoms, and urinalysis results suggestive of urinary tract infection (UTI). Eighty patients had a UTI proven by pre-therapy urine culture. Significantly more of the bacteria isolated were sensitive to cefaclor (96.3%) than to ampicillin (78.0%), P less than 0.01. Seventy-one patients returned for all follow-up visits and urine cultures. The overall success rate in the cefaclor group was 75.7% and in the ampicillin group 79.4%. There was a 10% failure rate in treating clinical cystitis with both regimens, and the satisfactory outcome rate for pyelonephritis and cystitis was similar in both treatment groups.