Actinomyces species

Microbiology

• Weakly Gram-positive bacterium that looks fungal under microscopy
• Oral and gut flora
• Spreads by direct invasion through tissue and creating fistulae

Syndromes

Cervicofacial actinomycosis

• "Lumpy jaw syndrome" with painless jaw mass, trismus, and eventually pain
• Most common form, accounting for ~50% of cases

Abdominal actinomycosis

• Presents as an abdominal mass that fistulizes to skin

Pulmonary actinomycosis

• Presents as a chronic, non-resolving pneumonia or as a lung cancer
• Can spread directly to involve heart as well

Others

• Endocarditis

Management

• IV penicillin x4-6 weeks then PO penicillin x6-12 months
• Alternatives include ceftriaxone, amox/clav