actinomycosis

Introduction

A chronic local or systemic granulomatous disease.

Etiology

• Actinomyces israelii (most common)
• other Actinomyces species

Pathology

• Actinomyces species are commensals in the mouth & GI tract
• portal of entry is through:
  • aspiration
  • a break in the integrity of the mucosa
• poor dental hygiene & dental abscess predispose to cervico- facial lesions
• within the GI tract, appendiceal abscesses are most common
• infection spread
  • direct extension
  • hematogenous dissemination
• pelvic actinomycosis
  • may originate in the female reproductive tract or intestine
  • IUDs left in place for more than 2 years increase risk
• histopathology:
  • grains (a few mm in diameter) surrounded by neutrophils
  • adjacent tissue shows subacute or chronic inflammation with fibrosis & formation of sinus tracts

Clinical manifestations

• General
  • multiple draining sinuses
  • pus contains 'sulfur granules'
• cervicofacial actinomycosis
  • red or purplish, indurated, firm
  • subcutaneous mass typically submandibular (jaw mass)
  • one or more draining sinuses may be present
  • tenderness is minimal
• pulmonary actinomycosis:
  • cough with purulent sputum
  • may present as subcutaneous abscess
  • weight loss, variable low-grade fever, lethargy
• abdominal actinomycosis
  • pain &/or palpable mass
  • weight loss, variable low-grade fever, lethargy
• cutaneous actinomycosis involving extremity (knee)

Laboratory

• complete blood count (CBC)
  • anemia & leukocytosis common in abdominal & thoracic actinomycosis
• Actinomyces antibody in serum
  • Actinomyces israelii Ab in serum
• microscopic examination of sulfur granules shows gram positive filaments
• Actinomyces identified by culture
  • growth in anaerobic culture
  • isolation of Actinomyces often difficult because of mixed flora often present in actinomycotic abscesses
• blood cultures are rarely positive

Radiology

• chest X-ray
  • dense pneumonitis may be seen
  • fibrosis, empyema or cavitation may be seen
• ultrasound may show abscess
• computed tomography (CT) may show abscess
• barium enema may show extrinsic mass

Differential diagnosis

• botryomycosis
• mycetoma
• Nocardia

Management

• mild cases
  • penicillin V 2-4 g/day
  • tetracycline
  • duration of therapy 2-4 months
• severe cases
  • penicillin G 2-6 million units/day for 6 weeks
  • followed by prolonged oral penicillin V or tetracycline
  • total duration of therapy 6-12 months
  • surgical resection of necrotic tissue
  • draining of abscesses
  • cutaneous actinomycosis treated with amoxicillin clavulanate for 1 year resulted in clinical improvement, but not complete resolution
• in general, not necessary to treat secondary micro-organisms isolated with Actinomyces

More general terms

• bacterial infection

Additional terms

• Actinomyces