Chlamydia trachomatis serovars L1, L2, L3 cause lymphogranuloma venereum (LGV). What is the pathognomonic inguinal finding and the preferred diagnostic laboratory method for LGV?
- A Soft chancre (painful ulcer) with inguinal adenitis; culture on McCoy cells
- B Painless hard chancre with bilateral painless inguinal lymphadenopathy; serology (TPPA)
- C Groove sign (inguinal ligament divides enlarged inguinal lymphadenopathy); NAAT (PCR) on rectal/urethral swab or bubo aspirate with LGV genotyping ✓
- D Multiple painful vesicles with tender inguinal adenopathy; PCR for HSV-2
Explanation
LGV (caused by C. trachomatis serovars L1-L3) classically presents with transient painless genital ulcer followed by inguinal lymphadenopathy showing the 'groove sign' — a depression running along the inguinal ligament dividing enlarged lymph nodes into groups above and below, caused by hyperplasia of femoral and inguinal nodes on each side of the ligament (Poupart's ligament). Preferred diagnosis is NAAT (PCR/molecular) on urethral/rectal swabs, urine, or bubo aspirate, with genotype-specific testing to confirm L serovars. Frei test (intradermal) is historical. McCoy cell culture is done for research.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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