Actinomycosis is a slowly growing infection caused by anaerobic or microaerophilic bacteria, primarily of the genus Actinomyces, which colonize the mouth, colon, and vagina. The most common presentation is painful abscesses with multiple draining sinuses.

1,000 (US); 20,000 (Global)
Actinomyces israelii infection; A. gerencseriae; A. naeslundii; A. odontolyticus; A. viscosus; A. turicensis; A. meyeri; Propionibacterium propionicum;
Days to months after precipitating event, e.g., trauma; [CCDM, p. 2]
Oral cervicofacial: abscess, otitis, sinusitis & canaliculitis; Thoracic: chest pain, fever & cough; Abdominal: abscess/mass or urogenital infection; Pelvic: pain, fever & bleeding; CNS: abscess; Soft tissue: sinus tracts; Disseminated: liver & lung;
Standard; "Not transmitted from person to person." [CDC 2007 Guideline for Isolation Precautions] Becomes part of normal oral flora; Infection rarely transmitted by human bite; [CCDM, p. 2]
Most common sites of infection are oral cervicofacial, thoracic, abdominal, pelvic, musculoskeletal, soft tissue, central nervous system (rarely), and disseminated (most commonly to liver and lungs). Risk factors include poor dental hygiene, intrauterine contraceptive devices, trauma, and treatment with immunosuppressants (anti-tumor necrosis factor alpha agents, glucocorticoids, bisphosphonates). [Harrisons, p. 500-1] The most common sites of infection are the jaw (55%), thorax (15%), and abdomen (20%) in which organisms grow in clusters (sulfur granules). [CCDM, p. 1-2] Sulfur granules are round, usually yellow, and <1 mm in diameter. Organisms are Gram positive. [Merck Manual, p. 1462-3] Person-to-person transmission has not been reported. The most common location of infection is submandibular. About 20% of patients have abdominal disease with weight loss, pain, and change in bowel movements. Hepatic involvement is common in disseminated disease; liver function tests may be normal. CNS infection is rare. Otitis media or sinusitis may be the source of chronic meningitis. The role played by the immune system in preventing or controlling this infection is not clear. Infections of joints after trauma and hematogenous seeding, including hip and knee prostheses, have been reported. Lymphadenopathy is uncommon in oral-cervicofacial disease. [PPID, p. 3072-77] Usually a mixed infection with Actinobacillus actinomycetemcomitans, Eikenella corrodens, Bacteroides spp, S. aureus and Streptococcus spp.; Similar to Nocardia on Gram stain, but Nocardia stains weakly AFB, and it usually infects the immunocompromised. Actinomyces are normal flora (mouth, GI tract, and genital tract). Chronic lesion is dense fibrosis (woody), draining fistulae, sulfur granules; it grows across rather than within tissue planes. [ABX Guide] "In the thoracic form, lung involvement resembles TB.". [Merck Manual, p. 1463] Chronic meningitis may arise from mouth or ear infections. [Cohen, p. 186t] Most cases are polymicrobial. This infection occurs when there is a breach in the mucosal integrity and often in the presence of foreign bodies; it is not clearly associated with immunocompromised patients. [ID, p. 1860] Most patients are immunocompetent, but corticosteroid therapy and AIDS are considered to be predisposing factors. [Cecil, p. 2030]
Identify sulfur granules in purulent material and gram-positive branching bacteria after Gram stain; Sulfur granules are usually yellow; [PPID, p. 3077]
  • >arthralgia
  • >fever
  • E nasal ulcers
  • E pharyngitis
  • E stomatitis
  • G abdominal mass
  • G abdominal pain
  • G constipation
  • G diarrhea
  • G liver function test, abnormal
  • G nausea, vomiting
  • H anemia
  • H leukocytosis
  • H lymphadenopathy
  • N headache
  • O conjunctivitis, acute
  • O oculoglandular syndrome
  • R chest pain
  • R cough
  • R hemoptysis
  • R sputum production
  • S pustule
  • S skin or subcutaneous nodule
  • S ulcer of skin
  • U hematuria
  • U pyuria
  • X cystic or cavitary lesions
  • X hilar lymphadenopathy
  • X lung infiltrates
  • X pleural effusions
  • *arthritis
  • *bowel obstruction
  • *brain abscess or lesion
  • *cranial neuropathy
  • *encephalitis
  • *endocarditis
  • *mediastinitis
  • *meningitis
  • *myocarditis
  • *osteomyelitis
  • *parotitis
  • *pericarditis
  • *pneumonia
  • *sepsis
  • *weight loss




  • AIDS patients
IV penicillin is the preferred drug. [ABX Guide] ". . medical therapy alone is usually sufficient for cure, including extensive invasive disease." [PPID, p. 3077]
1. (US) Annually reported cases were about 60 in the US in 1930-36; In the antibiotic era, about 1/100,000 in the Netherlands and 1/300,000 in Cleveland. [ID, p. 1858-9] Cases were common in the preantibiotic era. [PPID, p. 3071] Fewer than 100 cases/year are reported in the US, but many cases are probably not diagnosed. [Cecil, p. 2030] Incidence is about 1 in 300,000 in the US and 1 in 100,000 in Europe; [Gorbach, p. 64] 1 in 300,000 = 1000 in 300 million;
2. (Global) 20 X US cases/yr;