Actinomycosis is a chronic suppurative inflammation mainly caused by Actinomyces israeli. Fistulas are formed and pus with sulfur-colored particles flows out. According to modern biological classification, actinomycetes are not fungi but anaerobic bacteria. Because the lesions caused by them are similar to mycosis and in accordance with past habits, actinomycosis is usually still described together with fungal diseases. Actinomycetes have cell walls, whose chemical composition is similar to that of bacteria, and no nuclear membrane. The bacteria are filamentous, similar to fungi, and the thickness of the hyphae is similar to that of ordinary bacilli, generally not exceeding 1μm in diameter. The hyphae are branched and can be broken into rods. With the widespread use of antibiotics, the incidence of this disease has a downward trend.