Microbiology

• Actinomycosis can be difficult to diagnose and is often mistaken for other processes such as tumours.
• Diagnosis is made by examination of pus or biopsy specimens.  The presence of sulphur granules is pathognomonic, and on Gram staining the organisms appear as characteristic Gram-positive filaments.

Management of cervicofacial actinomycosis

Adequate surgical debridement and early treatment with antibiotics produces the best results, but response is slow and treatment must be prolonged.

The actinomycetes employ a range of strategies to avoid host defences, including the ability to survive intracellularly once engulfed by phagocytes and the establishment of cohesive colonies enmeshed in an extracellular matrix, which protects the organisms from antibiotics.  Treatment may need to be continued for up to one year.

Antibiotic rationale

Actinomycetes are susceptible to a wide range of antibiotics, including penicillins, tetracycline, erythromycin, clindamycin and ciprofloxacin.

Antibiotics must be given in high doses and for a long period.  Because of the long-term treatment required, which must continue after symptoms have resolved, the drug chosen should have a good tolerability profile.

Treatment for extensive actinomycosis might comprise:

• High-dose IV penicillin for 2–6 weeks.
  Followed by
• Oral penicillin for 6–12 months.

Many cervicofacial cases may require less extensive treatment and oral therapy alone with amoxicillin has been used successfully.

• Suitable alternative therapy in penicillin-allergic patients includes:
• Tetracycline
• Erythromycin (preferred in pregnancy)
• Doxycycline
• Clindamycin.

Surgery is required to aspirate abscesses; consult with an ENT surgeon. If the infection does not respond to treatment, drainage may reduce the burden of infection and allow successful antibiotic treatment.

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