Cat-scratch disease. Bacteria in skin at the primary inoculation site.

Cat-scratch disease is a zoonotic infection characterized by a skin papule at the site of the scratch followed by regional lymphadenitis. Recently, small gram-negative pleomorphic bacilli were demonstrated in sections of lymph node from patients with the disease. We now report identical bacteria in the primary inoculation site of three patients with cat-scratch disease. Lymph nodes from two of these patients also contained the same bacilli. Identical bacteria in both skin and lymph nodes from these patients are further evidence that the bacilli are the cause of cat-scratch disease. In early infections, biopsy of the primary site of inoculation and demonstration of bacilli may replace excision and histologic examination of lymph node in establishing the diagnosis of cat-scratch disease.