Actinomycosis of the colon: a rare form of presentation.

Actinomycosis is an uncommon entity, caused by an anaerobic bacterium, Actinomyces israelii, which is a component of the human oral and gastrointestinal flora. The cervicofacial region is the commonest site of disease, and the abdomen is the second commonest. In this situation the disease is almost always unifocal and restricted to the right colon, especially to the cecum. We report here the case of a patient with a very rare form of this entity, characterized by multiple foci of abdominal involvement with the most severe lesions localized in the transverse and sigmoid colon. The clinical presentation resembled a picture of colon perforation by cancer or diverticulitis, and the diagnosis was made by histopathologic examination of the lesions removed at surgery. No predisposing factor was found. The infection was successfully treated with a prolonged course of penicillin, after the surgical removal of the lesions.