Actinomycosis

Overview 
Theory 
Diagnosis 
Management 
Follow up 
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Last reviewed: 17 Mar 2025

Last updated: 11 May 2023

Actinomycosis is a rare, pyogenic, granulomatous, subacute to chronic infection caused by actinomycetes. Actinomycetes are a group of anaerobic gram-positive bacteria with high guanine-cytosine content found as natural flora of the oral cavity.

The most frequent features are ulcer and granuloma formation, and the presence of multiple abscesses and sinus tracts that may discharge sulfur granules. The pathogens often spread into neighbouring tissues.

Actinomycetes often invade the body by microfissures, and the most common clinical form of actinomycosis is cervicofacial, either after oral surgery or caused by poor dental hygiene. Thoracic and abdominal actinomycoses also occur frequently, and pelvic actinomycosis is possible in women.

Prolonged antibiotic treatment is necessary.

Definition

Actinomycosis is an infectious disease caused by anaerobic, gram-positive actinomycetes. The most common clinical forms of actinomycosis are cervicofacial and abdominal.[1] In women, pelvic actinomycosis is possible.[2] Many other sites of infection have been described, although less frequently than cervicofacial and abdominal actinomycoses. Because the disease is rare and most physicians have not seen a patient with actinomycosis, diagnosis is often delayed.

Whipple's disease, which may be interpreted as a special form of actinomycosis because it is caused by Tropheryma whipplei, a pathogen from the clade of actinomycetes, is not discussed here. See Whipple’s disease.