Chlamydia are a wide-branched family of bacteria that, depending on their subgroups, can cause various diseases. Chlamydia is an intracellular pathogen and requires cells from other organisms for its survival and multiplication. Two important subgroups can be distinguished:
1. Chlamydia pneumoniae
2. Chlamydia trachomatis
Infection with Chlamydia trachomatis is the most common sexually transmitted disease in the United States. In males, the urethra is infected and in females it can infect both urethra and cervix. It also causes pelvic inflammation, which can lead to infertility and ectopic pregnancy. An infected individual may never develop any signs or symptoms.