Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 33-33: Actinomycosis + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ History of recent dental infection, abdominal trauma, or intrauterine contraception device placement Chronic pneumonia or indolent cervicofacial or intra-abdominal abscess Sinus tract formation +++ General Considerations ++ Organisms are anaerobic, gram-positive, branching filamentous bacteria (1 mcm in diameter) that may fragment into bacillary forms Occur in the normal flora of the mouth and tonsillar crypts When introduced into traumatized tissue and associated with other anaerobic bacteria, actinomycetes become pathogens Most common site of infection is cervicofacial area (about 60% of cases) Infection typically follows extraction of a tooth or other trauma Lesions may develop in the gastrointestinal tract or lungs following ingestion or aspiration of the organism from its endogenous source in the mouth + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs +++ Cervicofacial actinomycosis ++ Develops slowly, becomes markedly indurated, and the overlying skin becomes reddish or cyanotic Abscesses eventually drain to the surface Persist for long periods Sulfur granules—masses of filamentous organisms—may be found in the pus There is usually little pain unless there is secondary infection +++ Thoracic actinomycosis ++ Fever, cough, sputum production Night sweats, weight loss Pleuritic pain Multiple sinuses may extend through the chest wall to the heart or abdomen +++ Abdominal actinomycosis ++ Pain in the ileocecal region Spiking fever and chills Vomiting Weight loss Irregular abdominal masses may be palpated Pelvic inflammatory disease caused by actinomycetes has been associated with prolonged use of an intrauterine contraceptive device Sinuses draining to the exterior may develop +++ Differential Diagnosis ++ Lung cancer Tuberculous lymphadenitis (scrofula) Other cause of cervical lymphadenopathy Nocardiosis Crohn disease Pelvic inflammatory disease from another cause + Diagnosis Download Section PDF Listen +++ +++ Laboratory Tests ++ Organisms may be demonstrated as a granule or as scattered branching gram-positive filaments in the pus Anaerobic culture is necessary to distinguish from Nocardia Histopathology exam of affected tissue and bone is useful in identifying organisms, which are fastidious and slow to culture +++ Imaging Studies ++ Chest radiograph shows areas of consolidation and, in many cases, pleural effusion Abdominal pelvic CT scanning reveals an inflammatory mass that may extend to involve bone + Treatment Download Section PDF Listen +++ +++ Medications ++ Penicillin G Drug of choice 10–20 million units intravenously for 4–6 weeks followed by penicillin V, 500 mg four times daily orally Alternatives include Ampicillin, 12 g/day intravenously for 4–6 weeks, followed by amoxicillin, 500 mg three times daily orally or Doxycycline, 100 mg twice daily intravenously or orally Sulfonamides such as sulfamethoxazole may be an alternative regimen at a total daily dosage of 2–4 g Therapy should be continued for weeks to months after clinical manifestations have disappeared in order to ensure cure +++ Surgery ++ Drainage and resection may be beneficial +++ Therapeutic Procedures ++ Therapy should be continued for weeks to months after clinical manifestations have disappeared in order to ensure cure Response to therapy is slow + Outcome Download Section PDF Listen +++ +++ Prognosis ++ With penicillin and surgery, the prognosis is good The difficulties of diagnosis may result in extensive destruction of tissue before therapy is started +++ When to Refer ++ Refer early to an infectious disease specialist for diagnosis and management +++ When to Admit ++ All patients with thoracic or abdominal actinomycosis Patients with cervicofacial actinomycosis if the diagnosis is in question, to control symptoms, or initiate intravenous antibiotics + References Download Section PDF Listen +++ + +Könönen E et al. Actinomyces and related organisms in human infections. Clin Microbiol Rev. 2015 Apr;28(2):419–42. [PubMed: 25788515] + +Steininger C et al. Resistance patterns in clinical isolates of pathogenic Actinomyces species. J Antimicrob Chemother. 2016 Feb;71(2):422–7. [PubMed: 26538502] + +Xu Y et al. Disseminated actinomycosis. N Engl J Med. 2018 Sep 13;379(11):1071. [PubMed: 30207906]