Actinomyces graevenitzii

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Gram stain Culture

General information
- Actinomyces graevenitzii is a newly recognized Actinomyces species that is seldom isolated from clinical specimens.
  
  This organism is an opportunistic human pathogen.
  
  Taxonomy
  Family: Actinomycetaceae
  
  Natural habitats
  It is possible a component of the oral pharyngeal flora.
  Very little is known about the clinical features and pathogenesis
  
  Clinical significance
  A. graevenitzii is believed to be associated with classic actinomycosis.
  
  Isolated from human clinical specimens, mainly respiratory tract secretions.
Gram stain
- Gram positive thick, granular rods
  
  of medium length, and branched.
Culture characteristics
- Facultative anaerobic
  
  5 % CO2 improves the growth
  
  BA: colonies are white, pronounced molar tooth or smooth and convex.
  They are small, 0.2 mm after 24 hours of incubation.
  
  The rough and smooth forms occur together.
  
  The colonies adhere very strongly to the agar surface.
  The adherence become less after repeated subculturing.
  
  Old colonies can be dark brown.
  
  Colonies are fluorescent red under the Wood's Lamp
  (Actinomyces selective agar with metronidazole 10 mg/l and nalidixic acid 30 mg/l))
  
  BBAØ: growth
Characteristics
References
- James Versalovic et al.(2011) Manual of Clinical Microbiology 10th Edition