infectious diseases
Actinomycosis
Key Points
Actinomycosis usually involves multiple, small, communicating abscesses with sinus tracts that drain a purulent discharge. Infection typically involves the neck and face, lungs, or abdominal and pelvic organs. Microscopically,Actinomycesappears as distinctive "sulfur" granules (rounded or spherical particles, usually yellowish, and≤1 mm in diameter) or as tangled masses of branched and unbranched wavy bacterial filaments. High-dose penicillin is usually effective but must be given long-term (8 weeks to 1 year). Surgery to drain abscesses and excise fistulas may be needed. 