Chlamydia infection is a common sexually transmitted infection in humans caused by the bacterium Chlamydia trachomatis. Chlamydia is a major infectious cause of human genital and eye disease. Chlamydia infection is one of the most common sexually transmitted infections worldwide.Symptoms that may occur include: a painful or burning sensation when urinating, an unusual discharge from the penis, testicular pain or swelling, or fever. The purulent penile discharge is generally not as thick and is lighter in color than that for gonorrhea. If left untreated, chlamydia in men can spread to the testicles causing epididymitis, which in rare cases can lead to sterility if not treated within 6 to 8 weeks.Chlamydia can usually be effectively treated with antibiotics. More than 95% of people will be cured if they take their antibiotics correctly. Most commonly prescribed antibiotics for chlamydia are azithromycin and doxycyclinze.