A 22-year-old man presents with painless urethral discharge. NAAT on urethral swab is positive for Chlamydia trachomatis. He is treated with a single dose of azithromycin 1 g. Six months later he returns with rectal bleeding and inguinal lymphadenopathy with grooves (groove sign/sign of the groove). Which Chlamydia trachomatis serovars are responsible for lymphogranuloma venereum (LGV)?

• A Serovars A, B, Ba, C (trachoma serovars)
• B Serovars D through K (urogenital serovars)
• C Serovars L1, L2, L2b, L3 (LGV serovars) ✓
• D Serovars E and F only (the most common urogenital serovars)

Explanation

Lymphogranuloma venereum (LGV) is caused exclusively by C. trachomatis serovars L1, L2 (and subtype L2b — emerging in men-who-have-sex-with-men), and L3. These serovars are more invasive than D-K serovars, spreading to regional lymphatics and causing the characteristic inguinal bubo with the pathognomonic groove sign (enlargement of lymph nodes above and below Poupart's ligament). Serovars A-C cause trachoma (ocular infections). D-K cause urogenital infections. LGV treatment requires doxycycline 100 mg BD for 21 days (not single-dose azithromycin).

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.