Single-dose amoxicillin therapy for urinary tract infection. Multicenter trial using antibody-coated bacteria localization technique.

Urine specimens from 134 women with acute, uncomplicated urinary tract infection at three medical centers were examined by the antibody-coated bacteria (ACB) assay. Patients with negative assays (suggesting bladder infection alone) were randomized to receive either a single 3-g oral dose of amoxicillin trihydrate or conventional ten-day courses of sulfa-methoxazole-trimethoprim or oral ampicillin sodium. Comparable results were obtained with the three regimens for ACG-negative infection: 90% eradication of the original organism with single-dose amoxicillin, 100% with sulfamethoxazole-trimethoprim, and 96% with ampicillin. The overall incidence of ACB positivity was 32.1%, ranging from 8% to 63% at the three institutions. This difference seemed to be related to the ease of access to medical care: women with easy access having low rates of ACB positivity and those with poor access having high rates.