Pediatric Actinomycosis Workup

Updated: Oct 28, 2021
  • Author: Jorge M Quinonez, MD; Chief Editor: Russell W Steele, MD  more...
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Laboratory Studies

Microbiologic identifications of the organisms that cause actinomycosis are uncommon. Diagnosis usually relies on the clinical picture and the presence of sulfur granules either observed macroscopically or microscopically. No serologic test or skin test for actinomycosis is available. Actinomyces is usually part of the normal flora; its presence on sputum samples, bronchial washings, or cervicovaginal secretions is not enough to make the diagnosis. Polymerase chain reaction has been used for diagnosis in some research laboratories.

  • Gram stain

    • Gram stain is more sensitive than culture.

    • Actinomyces are identified as gram-positive rods that are non–acid fast in diphtheroidal arrangement.

  • Hematoxylin-eosin stain of sulfur granules - Basophilic masses with a radiating border of eosinophilic terminal clubs

  • Culture

    • Tissue, pus, or sulfur granules are ideal.

    • Use anaerobic transport media.

    • No prior use of antibiotics is imperative.

    • Brain and heart infusion blood agar is cultured anaerobically or enriched with carbon dioxide.

    • Growth is in 5-7 days and may take 2-4 weeks.

  • Other useful stains

    • Grocott-Gomori methenamine-silver nitrate stain

    • P-aminosalicylic acid

    • Goodpasture stain

    • Brown-Brenn stain


Imaging Studies

CT scanning of the involved area is useful in differentiating between an inflammatory mass and a tumor. [12]

Abdominal and pelvic ultrasonographic studies have been used for diagnosing masses that may be due to actinomycosis.

Chest radiography in thoracic actinomycosis may provide some idea of the degree of pulmonary and pleural involvement; however, diagnosing the disease on the basis of radiographic findings alone is impossible.



Fine-needle aspiration, biopsy, CT scanning, or ultrasound-guided aspirations and biopsies can be successfully used to retrieve clinical materials for diagnosis.


Histologic Findings

Histologic diagnosis is difficult because many specimens contain only a few sulfur granules.

The use of a specific monoclonal antibody conjugated with fluorescein is a useful alternative that allows rapid identification by direct staining of clinical materials even after they have been fixed in formalin.