Actinomycosis of the colon and rectum

Two cases of primary actinomycotic infection involving the colon and rectum are reported. The cases illustrate different clinical modalities, from a localized and relatively benign form, to an extensive and overwhelming type of infection. Both patients recovered completely after surgical drainage and intensive penicillin therapy. The diagnosis can be most difficult, and may require a high index of clinical suspicion, as well as diligent search by the clinician, until the causative organism is identified.