Lymphogranuloma venerum is caused by which organism?

• A. Neisseria gonorrhoeae
• B. Treponema pallidum
• C. Chlamydia trachomatis
• D. Haemophilus ducreyi

Answer: (C)

Lymphogranuloma venereum is caused by Chlamydia trachomatis, specifically the L1–L3 serovars. This organism is an obligate intracellular bacterium that cycles between infectious elementary bodies and replicating reticulate bodies. Infection often starts with a small, sometimes unnoticed genital lesion, and weeks later leads to painful inguinal lymphadenopathy (buboes) and possible systemic symptoms. This pattern helps distinguish it from other sexually transmitted infections: Neisseria gonorrhoeae causes gonorrhea with purulent discharge, Treponema pallidum causes syphilis with a painless chancre and potential systemic disease, and Haemophilus ducreyi causes chancroid with a painful ulcer and tender nodes. Diagnosis is typically by nucleic acid amplification testing from the lesion or regional lymph nodes, and standard treatment options include doxycycline or azithromycin.