Listeria ivanovii

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Gram stain Culture

General information
- Taxonomy
  Family: Listeriaceae
  
  Of the seven species within the genus Listeria, only L. monocytogenes and L. ivanovii are pathogenic.
  
  Natural habitats
  They are widely distributed in the environment
  
  Clinical significance
  Listeria ivanovii is primarily a pathogen of ruminants.
  
  Systemic infections in immunodeficiency virus-infected and non-immunosuppressed patients have, however been described.
Diseases
- Listeriosis
Gram stain
- Regular, short gram positive rods,
  
  0.4-0.5 x 0.5-2.0 µm,
  
  that occur singly or in short chains.
  
  Filaments of 6-20 µm, may occur in older or rough cultures.
  
  Listeria may be confused with members of the coryneform rods (especially in direct slides from blood cultures), since the cells may be arranged in V forms or palisades.
Culture characteristics
- Facultative anaerobic
  
  5% CO2 stimulates growth
  
  BA: colonies are small, smooth, white-grey and produce a wide zone of hemolysis.
  
  McConkey: growth
  
  BBAØ: growth
  
  CAMP-test
  L.ivanovii ►CAMP-test negative (S.aureus streak)
  L.ivanovii ►CAMP-test positive (R.equi streak = a shovel shape)
Characteristics
References
- James Versalovic et al.(2011) Manual of Clinical Microbiology 10th Edition