Effect of treatment regimens for Neisseria gonorrhoeae on simultaneous infection with Chlamydia trachomatis.

We evaluated the effect of treatment of gonorrhea on simultaneous Chlamydia trachomatis infection by randomly assigning 293 heterosexual men and 246 heterosexual women with gonorrhea to receive one of the following treatment regimens: (1) 4.8 million units of aqueous procaine penicillin plus 1 g of probenecid, (2) nine tablets of trimethoprim-sulfamethoxazole daily for three days, or (3) 500 mg of tetracycline four times a day for five days. Among the men, gonococcal infection was cured in 99 per cent given penicillin plus probenecid, 96 per cent given trimethoprim-sulfamethoxazole, and 98 per cent given tetracycline. Among the women, only 90 per cent given tetracycline were cured, in contrast to 97 per cent given penicillin plus probenecid and 99 per cent given trimethoprim-sulfamethoxazole. Chlamydial infection, present in 15 per cent of the men and 26 per cent of the women, was cured in 30 of 32 patients given trimethoprim-sulfamethoxazole and 27 of 29 given tetracycline, but in only 10 of 23 given penicillin plus probenecid. Among chlamydia-positive patients, postgonococcal urethritis in men and cervicitis in women occurred more often in patients given penicillin plus probenecid. Salpingitis developed in 6 of 20 women given penicillin plus probenecid, but in only 1 of 26 given trimethoprim-sulfamethoxazole and in none of 24 given tetracycline. We conclude that the use of penicillin plus probenecid alone for gonorrhea in heterosexual patients carries an unacceptably high risk of postgonococcal chlamydial morbidity. Trimethoprim-sulfamethoxazole and tetracycline were highly effective against both pathogens and were well tolerated in men, but both drugs caused frequent side effects in women. The failure of tetracycline to cure gonorrhea in 10 per cent of women argues against its use alone; treatment with penicillin followed by tetracycline has been recommended for further trial.