Actinomycetes are fungus-like bacteria that form filamentous branches.
These Gram-positive obligate anaerobes are known to reside in the mouth and in the intestinal tract. Pathogenic proliferation of the organisms, which is usually a result of trauma to the region of infection, can lead to actinomycosis. The patient will form abscesses and swelling at the site of infection. A diagnosis can be made upon microscopic examination of pus. The fluid will have a granular texture which is caused by sulfur granules.