A 20-year-old sexually active woman presents with swelling of the vaginal labia. Examination of the perineal sharply defined subcutaneous bleeding nodules that appear to erode through the skin. The most likely etiologic agent in this case is

This patient is suffering from donovanosis, a chronic progressively destructive bacterial infection of the genital region that was formerly known as granuloma inguinale or granuloma venereum. This disease is caused by gram-negative pleomorphic encapsulated intracellular bacterium called C. granulomatis. Although there may be some patients who develop this disease on the basis of nonintimate contact, it is most likely that this is a sexually transmitted disease. The incubation is usually 1 to 4 weeks but may be longer. Most patients have disease limited to the genital area; extragenital lesions occur in about 6% and may include oral lesions and bleeding and/or bone disease. Diagnosis involves demonstration of intracellular Donovan bodies within the mononuclear cells obtained from a lesion. Syphilitic plaques are usually white rather than the red lesions characteristic of donovanosis. Donovanosis lesions can be so necrotic that squamous cell carcinoma m9Y be considered.