Actinomyces israelii

Actinomyces israelii

1. Characteristics

   • Gram-positive filamentous branching bacilli
   • Grows slowly
   • Anaerobic

2. Habitat

   • Found as scanty normal commensal in the :
     • Mouth, especially anaerobic crevices around the teeth
     • Colon
     • Vagina
     • Disease begins when these normal flora enter adjacent sterile tissue e.g, by trauma, surgery

3. Transmission

   • into tissues occurs during :
     • Dental extraction- poor dental hygiene
     • Trauma ( mouth - uterus)
     • Organism also aspirated into lungs, causing thoracic actinomycosis

4. Pathogenesis

   • Infection occur in both :
     • Normal hosts
     • Immunocompromised patients
   • Non toxins or virulence factor known
   • Organism forms sinus tracts that open on yellow " sulfur granules "
     • sulfur granules : are made up of large masses of organisms microcolonies of filamentous bacteria

5. Disease

   • Actinomycosis ( abscesses with draining sinus tracts )
   • Chronic suppurative abscess
   • The lesion ( Mycetoma ) :
     • Begins as a hard red swelling
     • Develops slowly, becomes filled with pus
     • Draining with sinus formation
   • Sites
     • Oral- facial abscesses (>50% of cases ) - often associated with trauma or dental extraction
     • Abdominal infections: Abscess. Many after appendicitis
     • Uterine infection : Associated with intrauterine contraceptive devices
     • Chest infection
     • Invasive infection in immunocompromised patients

6. Laboratory Diagnosis

   • Specimen: pus - Filaments may aggregate to form visible granules " Sulphur granules" in pus: Yellowish particles
   • Microscopy: sulfur granules : Gram-positive filamentous, branching rods
   • Culture: - Anaerobic culture on blood agar plate ( 10 days ) - Molar teeth colonies
   • No serologic tests

7. Treatment

   • Penicillin - For up to 3-12 months
   • Tetracyclin or Clindamycin - For penicillin-allergic patients
   • Surgical drainage

8. Prevention

   • Good oral hygiene
   • Prophylactic antibiotics in association with GIT or oral trauma or surgery
   • No vaccine is available

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