What is the most common sexually transmitted bacterial infection?

The most common sexually transmitted bacterial infection is chlamydia. It is caused mainly by the bacterium Chlamydia trachomatis, which can infect the cervix, urethra, rectum, throat, and eyes.

Chlamydia is especially difficult to detect because many infections cause no noticeable symptoms. When symptoms occur, they may include burning during urination or unusual genital discharge. Untreated infection can lead to pelvic inflammatory disease, infertility, ectopic pregnancy, or epididymitis, although complications are not inevitable.

A common mix-up is HIV, which is a virus rather than a bacterium. Syphilis and gonorrhea are also bacterial sexually transmitted infections, but chlamydia is generally identified as the most common bacterial STI in standard health references and surveillance discussions. Rankings can vary by country, year, reporting practices, and whether undiagnosed infections are estimated.

Testing usually uses a urine sample or a swab. Chlamydia is treatable with antibiotics, but reinfection is common if partners are not tested and treated. Condoms reduce transmission risk, and screening is important because symptoms alone cannot reliably identify infection.