<i>Actinomyces</i> and <i>Nocardia</i>

Both Actinomyces and Nocardia are Gram-positive rods that form fungus-like branched networks of hyphae-like filaments.

Actinomyces israelii

Basics

• chronic, progressive granulomatous disease caused by filamentous Gram-positive anaerobic bacteria from the Actinomycetaceae family.
• typically causes oral/facial abscesses with sulphur granules in sinus tracts
• may also cause an abdominal mass e.g. in the right iliac fossa

Actinomyces are commensal bacteria that become pathogenic when a mucosal barrier is breached.

The disease most commonly occurs in the head and neck, although it may also occur in the abdominal cavity and in the thorax.

The mass will often enlarge across tissue planes with the formation of multiple sinus tracts.

Abdominopelvic actinomycosis occurs most frequently in individuals that have had appendicitis (65%).

Pathology

• On histological examination Gram-positive organisms and evidence of sulphur granules.
• Sulphur granules are colonies of organisms that appear as round or oval basophilic masses.
• They are also seen in other conditions such as nocardiosis

Treatment

• Long-term antibiotic therapy usually with penicillin
• Surgical resection is indicated for extensive necrotic tissue, non-healing sinus tracts, abscesses or where biopsy is needed to exclude malignancy.

References
Wong V, Turmezei T and Weston V. Actinomycosis. BMJ 2011;343d6099.



Nocardia

Basics

• typically causes pneumonia in immunocompromised patients
• may also cause brain abscesses