Chlamydia trachomatis IgA antibody determination

Chlamydia – a sexually transmitted infection (STI) caused by the bacterium Chlamydia trachomatis.

It is the most common bacterial STI, often showing no symptoms. This can delay diagnosis and lead to transmission to sexual partners, potentially causing health issues related to fertility and sexual health, especially among young people.

Source of infection

The source of infection is a person infected with chlamydia. The incubation period ranges from 7 to 21 days. Up to 80% of women and 50% of men show no symptoms.

Routes of transmission

Chlamydia is transmitted during all types (vaginal, oral, anal; heterosexual or homosexual) of sexual intercourse. An infected mother can transmit the infection to her baby during childbirth.

Clinical presentation (incubation period, symptoms, complications)

Chlamydial infection is known as a “silent” infection because those infected often show no symptoms and do not complain. Only a third (up to 30%) of infected women show clinical signs of infection, while up to 75% of men do. Symptoms of chlamydia usually appear 7–14 days after infection. Common symptoms in women include mucous or purulent vaginal discharge, painful urination, a burning sensation during urination, difficulty urinating, bleeding after sexual intercourse, pain in the lower abdomen or during sex, bleeding between periods, and heavier periods. The chlamydial infection can spread from the cervix deeper into the urinary and reproductive organs, causing pelvic inflammatory disease (PID).

In men, chlamydia can present with white or clear discharge from the urethra, a burning sensation during urination, difficulty urinating, and itching around the urethral opening. Chlamydia can reach the internal urinary and reproductive organs, causing inflammation of the testicles and epididymis, leading to scrotal pain and swelling. Symptoms of rectal inflammation (pain, discharge, bleeding) may also occur. Inflammation of the prostate may cause aching pain in the sacrum, perineum, groin, testicles, and urethra, increased urination especially at night, decreased sexual potency, and fever.

The chlamydial pathogen can also reach the eyes through contaminated hands (Chlamydia trachomatis), causing eye inflammation. Untreated chlamydia can lead to infertility, chronic prostatitis, and pelvic inflammatory disease; it may also cause ectopic pregnancy. Infections acquired during anal intercourse may cause anal pain and bleeding.

IgA antibodies appear 2–3 weeks after infection, indicating active, ongoing, or chronic reactivated infection in the mucosa. They gradually disappear after successful treatment (over several months).

Interpretation of results

• IgA Positive (+):
• Indicates active or persistent (chronic) C. trachomatis infection.
• Together with positive IgG, confirms active or exacerbated chronic infection.
• If several months have passed after treatment and IgA remains positive (or its titer increases), it may indicate ineffective treatment, reinfection, or a persistent (prolonged) form of infection.