Effect of amoxicillin on simultaneous Chlamydia trachomatis infection in men with gonococcal urethritis: comparison of three dosage regimens.

Of 92 men with gonococcal urethritis who were treated orally with amoxicillin, 25 (27.1%) had a simultaneous Chlamydia trachomatis infection. At the first visit 25 patients were treated with a single dose of 1 g of amoxicillin plus 1 g of probenecid (group 1); 24 men were treated with 1 g of amoxicillin twice a day for two days (group 2); and 43 men were treated with 0.75 mg of amoxicillin three times a day for seven days (group 3). At the follow-up visit, one patient in each group still had Neisseria gonorrhoeae-positive cultures. C. trachomatis was not isolated again after treatment from men in group 3, but was isolated from 81.8% in groups 1 and 2 combined (P less than 0.05). One (10%) of the ten men in group 3 who were C. trachomatis-positive before treatment developed postgonococcal urethritis, as compared with seven (63.6%) of 11 in groups 1 and 2 combined (P less than 0.05). Thus a multiple-dose amoxicillin regimen may prove to be a useful alternative to the present-day treatment of chlamydial infections of the urogenital tract.