Actinomycosis

• Glenn G. Fort, M.D., M.P.H.

 Basic Information

Definition

Actinomycosis is an indolent, slowly progressive infection caused by anaerobic or microaerophilic bacteria, mostly from the genus Actinomyces, that normally colonize the mouth, vagina, and colon. Actinomycosis is characterized by the formation of painful abscesses, soft tissue infiltration, and draining sinuses.

Synonyms

1. Actinomyces infection

2. Lumpy jaw

ICD-10CM CODES
A42.9	Actinomycosis, unspecified
A42.0	Pulmonary actinomycosis
A42.1	Abdominal actinomycosis
A42.2	Cervicofacial actinomycosis
A42.89	Other forms of actinomycosis

Epidemiology & Demographics

Geographic Distribution

1. •

   Actinomycosis is worldwide in distribution.

2. •

   Commonly found as normal flora of the oral cavity (within gingival crevices, tonsillar crypts, periodontal pockets, dental plaques, and carious teeth), pharynx, tracheobronchial tree, gastrointestinal tract, and female urogenital tract

Incidence

1. •

   1:300,000 in 1970s but now less with better oral hygiene and antibiotic use

2. •

   Males infected more often than females (3:1)

3. •

   Can occur at any age but commonly seen in midlife

Physical Findings & Clinical Presentation

Actinomycosis can affect any organ. Although not typically considered as opportunistic pathogens, Actinomyces species capitalize on tissue injury or mucosal breach to invade adjacent structures in the head and neck regions. As a result, dental infections and oromaxillofacial trauma are common antecedent events. Characteristic manifestations include:

1. •

   Cervicofacial disease (most common site):

   1. 1.

      Occurs in the setting of poor dental hygiene, recent dental surgery, or minor oral trauma

   2. 2.

      Painful soft tissue swelling (Fig. E1) commonly seen at the angle of the mandible

      

   3. 3.

      Fever, chills, and weight loss

   4. 4.

      Trismus

   5. 5.

      Soft tissue facial infection with sinus tract or fistula formation

2. •

   Thoracic disease:

   1. 1.

      Can involve the lungs, pleura, mediastinum, or chest wall.

   2. 2.

      Presumed secondary to aspiration of Actinomyces organisms in patients with poor oral hygiene.

   3. 3.

      Fever, cough, weight loss, and pleuritic chest pains are common symptoms.

   4. 4.

      Signs of pneumonia or pleural effusion may be present.

   5. 5.

      With extension beyond the lungs to mediastinal structures and the chest wall, signs and symptoms of pericarditis, empyema, chest wall sinus drainage, and tracheoesophageal fistula can all occur (Fig. E2).

      

3. •

   Abdominal disease:

   1. 1.

      Occurs most commonly after appendectomy, perforated bowel, diverticulitis, or surgery to the gastrointestinal tract.

   2. 2.

      Lesions develop most commonly in the ileocecal valve, causing abdominal pain, fever, weight loss, and a palpable mass.

   3. 3.

      Extension may occur to the liver, causing jaundice and abscess formation.

   4. 4.

      Sinus tracts to the abdominal wall can occur.

4. •

   Pelvic disease:

   1. 1.

      Commonly occurs by extension from abdominal disease of the ileocecal valve to the right adnexa (80% of cases).

   2. 2.

      Endometritis.

Etiology

1. •

   Actinomycosis is most commonly caused by Actinomyces israelii. Other causes are A. naeslundii, A. odontolyticus, A. viscosus, and A. meyeri.

2. •

   Actinomyces are gram-positive, non–spore-forming, filamentous, anaerobic or microaerophilic rods.

3. •

   Actinomycosis infections are polymicrobial, usually associated with Eikenella corrodens, and Streptococcus, Bacteroides, Enterococcus, and Fusobacterium spp.

4. •

   Infects individuals only after entry into disrupted mucosa or tissue injury.

5. •

   Predisposing conditions include diabetes mellitus, malnutrition, and immunosuppression.

Diagnosis

Isolating the bacteria in the proper clinical setting makes the diagnosis of actinomycosis.

Differential Diagnosis

1. •

   Cervicofacial disease: odontogenic abscesses, brachial cleft cyst

2. •

   Pulmonary disease: nocardiosis, botryomycosis, chromomycosis, fungal disease of the lung, tuberculosis

3. •

   Intestinal disease: intestinal tuberculosis, ameboma, Crohn’s disease, colon cancer

4. •

   Pelvic disease: chronic pelvic inflammatory disease, Crohn’s disease

5. •

   CNS disease: other forms of brain abscess, brain tumors, toxoplasmosis, intracranial hematoma

Workup

The workup includes obtaining specimens either by aspirating abscesses, excising sinus tracts, or tissue biopsies. All specimens should be set up to culture anaerobic bacteria and held at least 5 to 7 days.

Laboratory Tests

1. •

   Isolating “sulfur granules” from tissue specimens or draining sinuses confirms the diagnosis of actinomycosis. Actinomyces are noted for forming characteristic sulfur granules in infected tissue but not in vitro. The term sulfur granule is a misnomer, reflecting only the yellow color of the granule in pus, because the granules are not composed of any sulfur at all.

   1. 1.

      Sulfur granules are nests of Actinomyces species. Sulfur granules may be macroscopic or microscopic.

   2. 2.

      Sulfur granules are crushed and stained for identification of Actinomyces organisms and may take up to 3 wk to grow in culture media.

Imaging Studies

Imaging studies are useful adjunctive tests in localizing the site and spread of infection.

1. 1.

   Chest x-ray examination.

2. 2.

   CT scan of the head, chest, abdomen, and pelvic areas is useful.

Treatment

Nonpharmacologic Therapy

1. •

   Incision and drainage of abscesses

2. •

   Excision of sinus tract

Acute General Rx

1. •

   Ampicillin 50 mg/kg/day in 3-4 divided doses x 4-6 wk; then Pen VK 2-4 g/day PO x 4-6 wk. In place of ampicillin, can also use penicillin 3-4 million units IV q4h for 4-6 wk.

2. •

   In penicillin-allergic patients, erythromycin (500-1000 mg IV q6h), tetracycline or doxycycline (100 mg IV q12h), and clindamycin (900 mg IV q8h) are reasonable alternatives. Other alternatives include ceftriaxone, imipenem, and piperacillin/tazobactam.

3. •

   Avoid use of metronidazole, aminoglycosides, oxacillin, and cephalexin.

Chronic Rx

1. •

   After 4 to 6 wk IV amoxicillin or penicillin, oral penicillin V 500 mg PO qid for 4 to 6 wk. Longer treatment with 6 to 12 months of antibiotic therapy is often necessary in some cases.

2. •

   Other available oral agents are erythromycin, doxycycline, and clindamycin.

3. •

   Treatment of associated microorganisms is not needed.

4. •

   Surgical debridement for complicated abscesses, fibrous tracts, necrotic tissues, fistulas, and bone involvement may also be required.

Disposition

1. •

   Clinical actinomycosis, if not treated, spreads to contiguous tissues and structures ignoring tissue planes. Hematogenous spread, although possible, is rare.

2. •

   Actinomycosis is very sensitive to antibiotics but requires chronic long-term treatment to prevent relapse.

Referral

If the diagnosis of actinomycosis is suspected, consultation with an infectious disease specialist is suggested. General surgical consultation for excision of sinus tracts and abscess incision and drainage is recommended.

Pearls & Considerations

Comments

1. •

   There is no person-to-person transmission of Actinomyces.

2. •

   Isolation of the organism in an asymptomatic individual does not mean the person has actinomycosis. Active symptoms must be present to make the diagnosis.

3. •

   Pelvic actinomycosis has been associated with use of an intrauterine device (IUD).

4. •

   Actinomycosis can also involve the CNS, causing multiple brain abscesses.

Suggested Reading

• S. Bonnefond, et al.: Clinical features of actinomycosis: a retrospective, multicenter study of 28 cases of miscellaneous presentations. Medicine (Baltimore). 95 (24):e3923 2016 27311002