Lung Abscess Caused by Actinomyces odontolyticus

A 64-year-old woman with periodontal disease was admitted because of fever, right chest pain, and bloody sputum. Her chest radiograph revealed a nodular shadow in the right middle lung fields. From the results of a needle aspiration biopsy, she was diagnosed with a lung abscess due to Actinomyces odontolyticus (A. odontolyticus) and Streptococcus spp. The patient improved quickly with antibiotics. To our knowledge, only nine cases of pulmonary infection due to A. odontolyticus have been reported, and we report the first case in Japan. Although respiratory disease caused by A. odontolyticus is rare, the association of this organism should be considered even in healthy individuals. (Internal Medicine 42: 723-725, 2003)