Francisella

  • Gram (-) coccobacilli 
  • Strict aerobes 
  • Urease (+)
  • motility (-)
  • oxidase (-) 
  • MAJOR VIRULENCE FACTOR – CAPSULE

Francisella spp.

Disease association

  • Tularemia – one of the most common lab acquired infection –
  • Rabbit fever 
  • Deer fly fever 
  • Market men’s disease

Laboratory diagnosis

  • BSL Level 2 Pathogen
  • Specimen:
    • scrapings from infected ulcers 
    • lymph node biopsies 
    • sputum
    • Whole blood 
      • acceptable specimen for all types of tularemia

Direct detection

  • Gram stain – little use with primary specimen.
  • Basic fuchsin– used as counterstain for better staining.

Media and Cultivation

  • Media with sulfhydryl compounds (cysteine, cystine, thiosulfate, or IsoVitaleX) – for primary isolation