Having been treated once for a bacterial STI like gonorrhea, syphilis or chlamydia does NOT protect you from future infections. Treatment with antibiotics helps get rid of STIs but it doesn't keep you from getting them again. Every day at SF City Clinic, we see patients with a new STI that they have had before. Each germ is a little different and your immune system does not always protect you. Condoms are the most effective way to protect yourself against STIs.