Last updated: September 20, 2021

Summarytoggle arrow icon

Actinomycosis is an infection caused by Actinomyces bacteria (especially Actinomyces israelii), which is ubiquitous in the oral cavity and is sometimes found in the gut or female genital tract. Actinomyces thrives in anaerobic environments, which are created by the proliferation of oxygen-consuming aerobic bacteria. The most frequent form of infection is cervicofacial actinomycosis, which occurs after injury to the oral cavity, face, or neck, although Actinomyces infection may also affect other parts of the body. The initial disease manifests as coarse, inflammatory nodules, which frequently develop into purulent, draining fistulae. Imaging enables a tentative diagnosis, but definitive diagnosis is based on culture and microscopic identification of Actinomyces. Antibiotics are used to treat actinomycosis and, in severe cases, surgery is required to remove lesions. Untreated cases of actinomycosis result in chronic, progressive disease.

Epidemiologytoggle arrow icon


Epidemiological data refers to the US, unless otherwise specified.

Etiologytoggle arrow icon


Predisposing factors


Pathophysiologytoggle arrow icon

Actinomyces is part of the normal flora of the oral cavity (less common in the lower gastrointestinal tract and female genital tract).

Actinomycosis infection spreads contiguously, with no regard for anatomical borders, and develops into multiple draining fistulae.


Clinical featurestoggle arrow icon

  • Cervicofacial actinomycosis
    • Slowly progressive mass in the neck and/or face; most commonly in the mandible region
    • Usually painless nodular lesions
    • Becomes indurated with purulent discharge that contains sulfur granules: from fistulae and draining sinus tracts. [3]
    • Canaliculitis: affects the lacrimal ducts or mouth, typically in the perimandibular region [2]
  • Abdominal and pelvic actinomycosis
    • Fever, abdominal discomfort, changes in bowel habits
    • Possible pathological vaginal bleeding or discharge
  • Thoracic actinomycosis

Diagnosticstoggle arrow icon

Suspected cases based on the clinical presentation (e.g., presence of sulfur granules) can be confirmed via identification of the organism from tissue specimen (e.g., pus, biopsy tissue from suspected lesion) or sulfur granules.

Definitive diagnosis is based on the identification of actinomycotic sulfur granules or bacteria.


Treatmenttoggle arrow icon

Prognosistoggle arrow icon

  • Adequate treatment often results in full recovery, however, early follow-up is required to identify possible recurrent infection.
  • Without treatment: chronic-progressive disease with contiguous spread (hematogenous spread is rare.)

Referencestoggle arrow icon

  1. Sharma S, Hashmi MF, Valentino III DJ. Actinomycosis. StatPearls. 2021.
  2. Canaliculitis. Updated: July 1, 2016. Accessed: March 24, 2017.
  3. Sulfur Granule. . Accessed: March 24, 2017.
  4. Huang R, Li M, Gregory RL. Bacterial interactions in dental biofilm. Virulence. 2011; 2 (5): p.435-444.doi: 10.4161/viru.2.5.16140 . | Open in Read by QxMD
  5. Valour F, Sénéchal A, Dupieux C et al. Actinomycosis: etiology, clinical features, diagnosis, treatment, and management. Infect Drug Resist. 2014; 7: p.183-197.doi: 10.2147/IDR.S39601 . | Open in Read by QxMD
  6. Actinomycosis. Updated: June 1, 2014. Accessed: March 24, 2017.
  7. Actinomycosis. Updated: January 1, 2016. Accessed: March 24, 2017.
  8. Pappas PG, Kauffman CA, Andes DR et al. Clinical Practice Guideline for the Management of Candidiasis: 2016 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2015; 62 (4): p.e1-e50.doi: 10.1093/cid/civ933 . | Open in Read by QxMD
  9. Actinomycosis. Updated: December 10, 2015. Accessed: March 24, 2017.

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