Actinomycosis

BASIC INFORMATION
Actinomycosis is a chronic bacterial infection characterized by the formation of painful abscesses, soft tissue infiltration, and draining sinuses.
SYNONYMS
Actinomyces infection
EPIDEMIOLOGY & DEMOGRAPHICS
• Actinomycosis is worldwide in distribution.
• Commonly found as normal flora of the oral cavity, pharynx, tracheobronchial tree, gastrointestinal tract, and female urogenital tract.
• Incidence 1:300,000.
• Males infected more often than females 3:1.
•Can occur at any age but commonly seen in midlife.

• Incidence has decreased since the 1950s and is attributed to better oral hygiene and antibiotics.
PHYSICAL FINDINGS & CLINICAL PRESENTATION
Actinomycosis can affect any organ and characteristically manifests as:
• Cervicofacial disease (most common site):
1. Occurs in the setting of poor dental hygiene, recent dental surgery, or minor oral trauma
2. Painful soft tissue swelling commonly seen at the angle of the mandible
3. Fever, chills, and weight loss
4. Trismus
5. Soft tissue facial infection with sinus tract or fistula formation
• Thoracic disease:
1. Can involve the lungs, pleura, mediastinum, or chest wall.

2. Presumed secondary to aspiration of Actinomyces organisms in patients with poor oral hygiene.
3. Fever, cough, weight loss, and pleuritic chest pains are common symptoms.
4. Signs of pneumonia or pleural effusion may be present.
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.
• Abdominal disease:
1. Occurs most commonly after appendectomy, perforated bowel, diverticulitis, or surgery to the gastrointestinal tract.
2. Lesions develop most commonly in the ileocecal valve, causing abdominal pain, fever, weight loss, and a palpable mass.
3. Extension may occur to the liver, causing jaundice and abscess formation.
4. Sinus tracts to the abdominal wall can occur.
• Pelvic disease:
1. Commonly occurs by extension from abdominal disease of the ileocecal valve to the right adnexa (80% of cases).
2. Endometritis.
ETIOLOGY
• Actinomycosis is most commonly caused by Actinomyces israelii. Other causes are A. naeslundii, A. odontolyticus, A. viscosus, A. meyeri, and A. gerencseriae.

• Actinomyces are gram-positive, non-spore-forming, anaerobic or microaerophilic rods.
• Actinomycosis infections are polymicrobial, usually associated with Streptococcous, Bacteroides, Eikenella corrodens, Enterococcus, and Fusobacterium.
• Infects individuals only after entry into disrupted mucosa or tissue injury.
DIAGNOSIS
Isolating the bacteria in the proper clinical setting makes the diagnosis of actinomycosis.
DIFFERENTIAL DIAGNOSIS
Nocardiosis, botryomycosis, chromomycosis, intestinal tuberculosis, ameboma, Crohn’s disease, colon cancer, and other causes of acute, subacute, or chronic infections of the lung, abdomen, hepatic, GI, GU, musculoskeletal, and CNS system.
WORKUP
The workup includes obtaining specimens either by aspirating abscesses, excising sinus tracts, or tissue biopsies.
LABORATORY TESTS
• Isolating “sulfur granules” from tissue specimens or draining sinuses confirm the diagnosis of actinomycosis.
1. Sulfur granules are nests of Actinomyces species. Sulfur granules may be macroscopic or microscopic.
2. Sulfur granules are crushed and stained for identification of Actinomcyes organisms and may take up to 3 wk to grow in culture media.
TREATMENT
NONPHARMACOLOGIC THERAPY
• Incision and drainage of abscesses
• Excision of sinus tract
ACUTE GENERAL Rx
• Penicillin 10 to 20 million units per day in 4 divided doses for 4 to 6 wk.
• In penicillin-allergic patients, erythromycin, tetracycline, clindamycin, or cephalosporins (depending on the type of penicillin allergy) are reasonable alternatives.
• Chloramphenicol 50 to 60 mg/kg/day has been used for CNS actinomycosis.
CHRONIC Rx
• Following 4 to 6 wk IV penicillin, oral penicillin V 500 mg PO qid for 6 to 12 mo.
• Treatment of associated microorganisms is not needed.
DISPOSITION
• Clinical actinomycosis, if not treated, spreads to contiguous tissues and structures ignoring tissue planes. Hematogenous spread, although possible, is rare.
• 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.