Sulfa drugs were commonly used against Gonorrhea and Chlamydia in the 30's and 40's and still remain effective against Chlamydia....not so much against Gonorrhea. However, resistance to sulfa drugs has steadily increased and typically treatment for one includes treatment for the other.. and today Chlamydia is usually treated with doxycycline.
Do you know what the dosage would be for Sulfamethoxazole-trimethoprim to work on Chlamydia?
I'm afraid I can't answer that question. I'm not a doctor. I'll see if I can find any info though.