actinomycosis /ak′tinōmīkō″sis/ , a chronic bacterial disease most frequently located in the jaw, thorax, or abdomen. It is characterized by deep, lumpy abscesses that extrude a thin, granular pus through multiple sinuses. The disease occurs worldwide but is seen most frequently in those who live in rural areas. It is not spread from person to person or from animals to humans. The most common causative organism in humans is Actinomyces israelii, a normal inhabitant of the bowel and mouth. Disease occurs after tissue damage, usually in the presence of another infectious organism. It can be diagnosed by microscopic identification of sulfur granules, pathognomonic of Actinomyces, in the exudate. There are several forms of actinomycosis. Orocervicofacial actinomycosis occurs with the spread of the bacterium into the subcutaneous tissues of the mouth, throat, and neck as a result of dental or tonsillar infection. Thoracic actinomycosis may represent proliferation of the organism from cervicofacial abscesses into the esophagus, or it may result from inhalation of the bacterium into the bronchi. Abdominal actinomycosis usually follows an acute inflammatory process in the stomach or intestines, such as appendicitis, diverticulum of the large bowel, or a perforation found in the groin or another area that drains exudate into the stomach. A large mass may be palpated, and sinus tracts from abscesses deep in the abdomen may form. Pelvic actinomycosis is most commonly associated with intrauterine devices. Central nervous system actinomycosis is a rare cause of brain abscess. Bacterial endocarditis is very rarely caused by actinobacillus infection. Musculoskeletal actinomycosis involves subcutaneous tissue, muscle, and bone. Disseminated Actinomycosis follows hematogenous spread of the infection and may involve the skin, brain, liver, and urogenital system. All forms of actinomycosis are treated with at least 6 weeks of daily injections of penicillin in large doses. Abdominal actinomycosis can be cured in 40% of cases, thoracic actinomycosis in 80%, and orocervicofacial actinomycosis in 90%.
