Chlamydia trachomatis Antibody, IgG

The Chlamydia trachomatis Antibody, IgG assay (also reported as Anti-Chlamydia trachomatis IgG or Chlamydia trachomatis IgG antibody) is used to corroborate prior exposure or established infection when interpreted alongside other serologic markers, microbiologic results, and the clinical presentation. It also assists in evaluations where evidence of previous Chlamydia trachomatis infection informs risk assessment or management, including workups for tubal factor infertility or review of a history of ectopic pregnancy.

Chlamydia trachomatis is an obligate intracellular pathogen that alternates between an infectious elementary body and a replicative reticulate body during a biphasic developmental cycle. The organism targets mucosal epithelium of the urethra, endocervix, rectum, conjunctiva, and oropharynx and is transmitted through sexual contact or from mother to infant at delivery. In women, infection commonly presents as cervicitis and can ascend to cause salpingitis, with potential sequelae including tubal obstruction, infertility, or ectopic pregnancy. In men, manifestations include urethritis, epididymitis, and prostatitis. Neonates exposed intrapartum may develop conjunctivitis or pneumonia. Humoral responses involve IgM, IgA, and IgG at different phases of infection. IgG typically appears 3–4 weeks after a primary infection and can remain detectable for prolonged periods after clinical resolution. Accordingly, a positive IgG result supports prior exposure or established infection but does not indicate acute infection on its own and requires interpretation in the context of symptoms and other laboratory findings.