Aetiology

Infections are caused by the bacterium Chlamydia trachomatis.[2][5]

Chlamydia is almost always transmitted by sexual contact. The bacterium may cause symptoms, but in most people the infection is asymptomatic.[1]

Pathophysiology

Chlamydia trachomatis is a small Gram-negative bacterium that lives as an obligate intracellular parasite.[7] It has two life-cycle phases. During the first phase, the organism enters the cell and forms large inclusion bodies called elementary bodies. The elementary bodies re-organise into smaller, reticulate bodies. The reticulate bodies replicate and mature back into elementary bodies. Once the maturation is complete, the cell ruptures within 2 to 3 days. The freed bacteria then penetrate other cells to continue the replication process.[8] Due to this unique life-cycle, the organism cannot be cultured on artificial media.[9]

After exposure to C trachomatis, the incubation period is usually 7 to 21 days. Infection in the urogenital tract leads to urethral inflammation or cervical inflammation in women. In some cases, the infection can migrate up into the reproductive tract in women and cause an infection in the pelvis, pelvic inflammatory disease (PID), or peri-hepatitis (Fitzhugh-Curtis' syndrome). In men, ascension of the infection can lead to epididymitis or prostatitis.[2]

Classification

Serotypes L1, L2, L3

Lymphogranuloma venereum (LGV): more invasive serotype causing genital ulcer and/or inguinal lymphadenopathy, or proctitis with rectal infection.

Serotypes A, B, Ba, C

Ocular trachoma.

Serotypes B, Ba, D through to K

Oculogenital disease in adults and children, infant pneumonia.

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