Highlights & Basics
- Actinomycosis is a rare, pyogenic granulomatous, subacute to chronic infection caused by actinomycetes. Actinomycetes are a group of anaerobic gram-positive bacteria with high guanine-cytosine content found as natural flora of the oral cavity.
- The most frequent features are ulcer and granuloma formation, and the presence of multiple abscesses and sinus tracts that may discharge sulfur granules. The pathogens often spread into neighboring tissues.
- Actinomycetes often invade the body by microfissures, and the most common clinical form of actinomycosis is cervicofacial, either after oral surgery or caused by poor dental hygiene. Thoracic and abdominal actinomycoses also occur frequently, and pelvic actinomycosis is possible in women.
- Prolonged antibiotic treatment is necessary.
Quick Reference
History & Exam
Key Factors
soft-tissue swelling
Other Factors
multiple sinuses
skin discoloration
chewing difficulties
constitutional symptoms
change in bowel habits
abdominal discomfort
nausea and vomiting
sensation of abdominal mass
vaginal bleeding or discharge
dry or productive cough
blood-streaked sputum
shortness of breath
chest pain
focal neurologic defects
Diagnostics Tests
1st Tests to Order
culture of pus or affected tissue
histology of affected tissue
immunohistology
CBC
CT or MRI of abdomen
Emerging Tests
PCR of affected tissue
Treatment Options
acute
non-penicillin allergic
non-penicillin allergic
with extensive lesions, extensive necrosis, large abscess formation, and/or persistent fistula
penicillin allergic
penicillin allergic
with extensive lesions, extensive necrosis, large abscess formation, and/or persistent fistula
Definition
Classifications
Taxonomic classification
Vignette
Common Vignette 1
Common Vignette 2
Epidemiology
Etiology
Pathophysiology
Images
Diagnostic Approach
Cervicofacial actinomycosis
- Mandible (54%)
- Cheek (16%)
- Chin (13%)
- Submaxillary ramus and angle (11%)
- Upper jaw (6%).Image
Abdominal and pelvic actinomycosis
Other manifestations
Laboratory tests: general considerations
- Direct cultivation of the agent from affected tissue
- Histology and immunohistology.
Culture
Histology and immunohistology
Other laboratory techniques
Risk Factors
History & Exam
Tests
Differential Diagnosis
Abdominal abscess
Differentiating Signs/Symptoms
- Features of sepsis or an acute abdomen are generally prominent, although the early symptoms of abdominal actinomycosis may be similar to an abdominal abscess.
Differentiating Tests
- Histology and culture for actinomycetes are negative.
- Blood or site cultures identify etiologic organism.
Ovarian or oviductal tumor
Differentiating Signs/Symptoms
- Symptoms may be similar to pelvic actinomycosis. However, the association of a pelvic mass in an IUD user strongly suggests the diagnosis of actinomycosis. Leukorrhea is less likely to be present.
Differentiating Tests
- Histopathology shows malignancy. Histology and culture for actinomycetes are negative.
Appendicitis
Differentiating Signs/Symptoms
- Features of an acute abdomen are generally prominent, but symptoms may be otherwise similar to abdominal actinomycosis.
Differentiating Tests
- Histology and culture for actinomycetes are negative.
Blastomycosis
Differentiating Signs/Symptoms
- Lung blastomycosis may spread to the skin, but otherwise symptoms may be similar to pulmonary actinomycosis.
Differentiating Tests
- Sputum smear and culture using KOH preparations or specific stains can confirm diagnosis. Histology and culture for actinomycetes are negative.
Brain abscess
Differentiating Signs/Symptoms
- Clinical features may be similar to actinomycosis of the CNS.
Differentiating Tests
- Blood cultures may be positive with a bacterial abscess. Histology and culture for actinomycetes are negative.
Colon cancer
Differentiating Signs/Symptoms
- Clinical features of abdominal actinomycosis may mimic colon cancer.
Differentiating Tests
- Histology shows malignant tissue. Histology and culture for actinomycetes are negative.
Gastric adenocarcinoma
Differentiating Signs/Symptoms
- Symptoms of abdominal actinomycosis may mimic gastric adenocarcinoma.
Differentiating Tests
- Histology shows malignant tissue. Histology and culture for actinomycetes are negative.
Crohn disease
Differentiating Signs/Symptoms
- Clinical features may be indistinguishable from abdominal actinomycosis.
Differentiating Tests
- Colonoscopy shows skip lesions. Biopsy shows characteristic changes. Histology and culture for actinomycetes are negative.
Ulcerative colitis
Differentiating Signs/Symptoms
- Clinical features may be indistinguishable from abdominal actinomycosis.
Differentiating Tests
- Biopsies show continuous distal disease with characteristic changes and an absence of granulomata. Histology and culture for actinomycetes are negative.
Diverticulitis
Differentiating Signs/Symptoms
- Clinical features may be indistinguishable from abdominal actinomycosis.
Differentiating Tests
- Colonoscopy or sigmoidoscopy may show diverticula. Histology and culture for actinomycetes are negative.
Liver abscess
Differentiating Signs/Symptoms
- Clinical features may be indistinguishable from abdominal actinomycosis.
Differentiating Tests
- Blood cultures may be positive in pyrogenic liver abscess. Histology and culture on aspirated fluid is negative for actinomycetes. Ultrasound demonstrates a variably echoic lesion.
Lung abscess
Differentiating Signs/Symptoms
- Clinical features may be indistinguishable from thoracic actinomycosis.
Differentiating Tests
- Very high WBC count is common. Sputum Gram stain and culture may reveal a causative pathogen. Histology and culture for actinomycetes are negative.
Differentiating Signs/Symptoms
- Clinical features may be indistinguishable from thoracic actinomycosis.
Differentiating Tests
- Sputum cytology may reveal malignant cells. Biopsy shows malignant cells. Histology and culture for actinomycetes are negative.
Nocardiosis
Differentiating Signs/Symptoms
- Clinical features may be indistinguishable from abdominal actinomycosis.
Differentiating Tests
- Modified acid-fast staining of biopsy tissue or other samples allows distinction between Nocardia and Actinomyces.
Pelvic inflammatory disease
Differentiating Signs/Symptoms
- History of recent sexual contact, recent onset of menses, or a sexually transmitted infection in the partner, as well as a past history of PID, are common. However, the clinical symptoms of PID may resemble pelvic actinomycosis, and definitive diagnosis requires laparoscopy with biopsy sampling followed by histology.
Differentiating Tests
- Culture of vaginal secretions may be positive for a sexually transmitted organism. Endometrial biopsy may show changes of endometritis. Histology and culture for actinomycetes are negative.
Pneumonia (fungal, bacterial, or aspiration)
Differentiating Signs/Symptoms
- Clinical features may be indistinguishable from thoracic actinomycosis.
Differentiating Tests
- Sputum Gram stain and culture may reveal a causative pathogen. Histology and culture for actinomycetes are negative.
- CXR may typically show focal changes in bacterial pneumonia, with large pleural effusion, cavitating changes indicating an abscess, or multifocal or interstitial changes.
Pulmonary tuberculosis
Differentiating Signs/Symptoms
- Clinical features may be indistinguishable from thoracic actinomycosis.
Differentiating Tests
- Sputum smear and culture positive for acid-fast bacilli. Tuberculin skin testing is usually positive. Histology and culture for actinomycetes are negative.
Intestinal tuberculosis
Differentiating Signs/Symptoms
- Clinical features may be indistinguishable from abdominal actinomycosis.
Differentiating Tests
- Histology and culture of infected tissue positive for acid-fast bacilli. Tuberculin skin testing is usually positive. Histology and culture for actinomycetes are negative.
Uterine cancer
Differentiating Signs/Symptoms
- Clinical features may be indistinguishable from pelvic actinomycosis.
Differentiating Tests
- Biopsy tissue at laparoscopy shows malignant tissue. Histology and culture for actinomycetes are negative.
Differentiating Signs/Symptoms
- Typically presents as an acute GI illness, with fever, diarrhea, and weight loss, often with features of malabsorption such as steatorrhea, edema, fatigue, and lethargy. A severe wasting syndrome with abdominal lymphadenopathy and abdominal pain may develop. Joint problems often occur, and a seronegative migratory arthralgia of the large joints or other forms of arthritis may be the presenting feature. Most patients are anemic.
Differentiating Tests
- Anti-Tropheryma whipplei-positive macrophages, carried out on biopsied tissue, are a diagnostic marker. Polymerase chain reaction testing of duodenal biopsies positive for T whipplei (although carriers may also have positive results).
Treatment Approach
Management and antibiotic treatment
Excision of lesions
Treatment Options
non-penicillin allergic
penicillin or amoxicillin
Primary Options
penicillin G potassium
10-20 million units/day intravenously/intramuscularly given in divided doses every 4-6 hours for 4-6 weeks
and
penicillin V potassium
2-4 g/day orally given in 4-6 divided doses for 3-6 months after cessation of intravenous therapy
- ampicillin
50 mg/kg/day intravenously given in divided doses every 8 hours for 4-6 weeks
and
- amoxicillin
500 mg orally three times daily for 3-6 months after cessation of intravenous therapy
- ampicillin
Comments
- Prolonged high-dose antibiotic therapy with a penicillin is the preferred treatment. Given parenterally for 4 to 6 weeks, followed by oral therapy for a further 3 to 6 months. Parenteral therapy can be given on an inpatient or outpatient basis, depending on severity of disease.[1] [11] [51] [59] Consultation with an expert in microbiology or infectious diseases is recommended.[7]
with extensive lesions, extensive necrosis, large abscess formation, and/or persistent fistula
surgical excision of lesions
Comments
- These patients may require surgery to excise the lesions in addition to antibiotics.[58]
penicillin allergic
non-penicillin antibiotics
Primary Options
- ceftriaxone
2 g intravenously/intramuscularly every 12-24 hours for 4-6 weeks
and
- doxycycline
100 mg orally twice daily for 3-6 months after cessation of intravenous therapy
- ceftriaxone
- erythromycin lactobionate
500 mg intravenously every 6 hours for 4-6 weeks
and
- erythromycin base
500 mg orally twice daily for 3-6 months after cessation of intravenous therapy
- erythromycin lactobionate
- doxycycline
100 mg twice daily orally for 4-6 months
- doxycycline
Comments
- Patients with mild cervicofacial actinomycosis of endodontic origin may be given oral doxycycline from the outset. Consultation with an expert in microbiology or infectious diseases is recommended.[7]
with extensive lesions, extensive necrosis, large abscess formation, and/or persistent fistula
surgical excision of lesions
Comments
- These patients may require surgery to excise the lesions in addition to antibiotics.[58]
Emerging Tx
Chloramphenicol in CNS disease in patients allergic to penicillin and ceftriaxone
Prevention
Secondary Prevention
Follow-Up Overview
Prognosis
Monitoring
Citations
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Acevedo F, Baudrand R, Letelier LM, et al. Actinomycosis: a great pretender: case reports of unusual presentations and a review of the literature. Int J Infect Dis. 2008 Jul;12(4):358-62.[Abstract]
Wong VK, Turmezei TD, Weston VC. Actinomycosis. BMJ. 2011 Oct 11;343:d6099.[Abstract]
Martin MV. The use of oral amoxycillin for the treatment of actinomycosis: a clinical and in vitro study. Br Dent J. 1984 Apr 7;156(7):252-4.[Abstract]
Spilsbury BW, Johnstone FR. The clinical course of actinomycotic infections: a report of 14 cases. Can J Surg. 1962 Jan;5:33-48.[Abstract]
Sudhakar SS, Ross JJ. Short-term treatment of actinomycosis: two cases and a review. Clin Infect Dis. 2004 Feb 1;38(3):444-7.[Abstract][Full Text]
Bennhoff DF. Actinomycosis: diagnostic and therapeutic considerations and a review of 32 cases. Laryngoscope. 1984 Sep;94(9):1198-217.[Abstract]
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