A 28-year-old man presents with painful genital ulcers followed by tender unilateral inguinal swelling. Examination shows a groove between the femoral and inguinal portions of the swollen mass. Which organism is the most likely cause?
- A Treponema pallidum
- B Haemophilus ducreyi
- C Chlamydia trachomatis serotypes L1-L3 ✓
- D Klebsiella granulomatis
Correct answer: C. Chlamydia trachomatis serotypes L1-L3
Explanation
The groove sign is characteristic of lymphogranuloma venereum, caused by Chlamydia trachomatis biovar lymphogranuloma venereum serotypes L1 to L3. The groove separates enlarged femoral nodes from enlarged inguinal nodes because lymph from the vulvar fourchette drains along the round ligament to femoral nodes while penile and scrotal lymph goes to inguinal nodes. Chancroid causes painful ulcers with inguinal bubo but no groove sign.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.