Chlamydia is a sexually transmitted disease (STD) caused by a common bacterium that can cause serious complications if not treated. It’s a serious disease that often has minimal or no symptoms. Chlamydia testing identifies the bacteria Chlamydia trachomatis as the cause of a person’s infection. If you do have symptoms, some include painful urination, vaginal discharge and abdominal pain (for women) or unusual discharge from the penis, and pain on urination (for men). These symptoms are very similar to Gonorrhea, so you might want to consider the comprehensive STD panel; it tests for Chlamydia and Gonorrhea, as well as several others.