A 31-year-old Haitian woman is evaluated for infertility. Pelvic examination shows a markedly enlarged vulva, inguinal lymph node enlargement, and rectal stricture. Biopsy of an inguinal lymph node reveals necrotizing granulomas, neutrophilic infiltrates, and inclusion bodies within macrophages. Which of the following is the most likely etiology of infertility in this patient?

Lymphogranuloma venereum is a sexually transmitted infection that is endemic in tropical countries but rare in developed ones. The disease is caused by C. trachomatis, which is a Gram-negative obligate, intracellular rickettsia. This organism has been found in the genital tract of about 8% of asymptomatic women and in 20% of women presenting with symptoms of a lower genital tract infection. After a few days to a month, a small painless vesicle forms at the site of inoculation. It heals rapidly, and in many instances, the vesicle is not even noticed. The second stage presents with bilaterally enlarged inguinal lymph nodes that may rupture and form suppurative fistulas. In some untreated patients, a third stage appears, which causes lymphatic obstruction and resulting genital elephantiasis and rectal strictures. Mycobacterium tuberculosis (choice D) induces granulomatous inflammation but does not feature inclusion bodies. Gardnerella vaginalis (choice B) causes nonspecific vaginitis. Molluscum contagiosum (choice C) does not involve the lymph nodes. Treponema pallidum (choice E) does not cause granulomas.Diagnosis: Lymphogranuloma venaereum