Etiology

Pathogen

• Actinomyces are primarily anaerobic, gram-positive, non-acid fast, branching, rod-shaped bacteria.
• Actinomyces bacteria, particularly Actinomyces israelii, are found in the normal oral flora.

Predisposing factors

• Cervicofacial actinomycosis (most frequent form of actinomycosis)
  • Poor dental hygiene (e.g., dental caries)
  • Oral surgery (e.g., tooth extraction)
  • Maxillofacial trauma
  • Local tissue inflammation (e.g., tonsillitis, tumor)
  • Comorbidities (e.g., diabetes)
• Abdominal and pelvic actinomycosis (See PID)
  • Intestinal surgery
  • Foreign body ingestion
  • Tumor
  • Ascending infection from the uterus, associated with intra-uterine contraceptive devices
• Thoracic actinomycosis
  • History of aspiration
  • Recent oral infection

Clinical features

• 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.
    • Sulfur granules refer to macroscopic grains – approx. 1 mm in diameter – of hard clumps of bacterial filaments, pus, debris, and hyaline. The granules appear yellow within pus, although despite the name they do not contain sulfur.
• Thoracic actinomycosis
  • Cough, chest pain
  • Possible hemoptysis with yellow granules

Diagnostics

• Microscopy: direct visualization and staining of specimen → accumulations of radially protruding and branching Actinomyces (conglomerates with a “cauliflower-like” appearance) that are surrounded by numerous granulocytes

An aggregate of basophilic bacteria with radially branching filaments is visible at the center, which has a cauliflower-like appearance (yellow overlay).
The bacteria are surrounded by numerous granulocytes, resulting in a lesion with a rosette-like pattern (green overlay).

This is the typical histopathological appearance of a yellow “sulfur granule” caused by actinomycosis.

Treatment

Penicillin