Francisella tularensis
MICROBIOLOGY
- Small, pleomorphic, intracellular and extracellular fastidious aerobic Gram-negative coccobacillus [Fig 1].
- Culture: poor or no growth on standard media.
- Media most often employed: Thayer-Martin, BCYE or chocolate agar with the addition of cysteine and/or cysteine (thioglycolate).
- MacConkey and other conventional media will not yield growth.
- A slow grower may require CO2 supplementation.
- Media most often employed: Thayer-Martin, BCYE or chocolate agar with the addition of cysteine and/or cysteine (thioglycolate).
- Considered an important laboratory hazard to laboratory personnel requiring specialized safety procedures. Notify the lab if considering diagnosis when submitting specimens; higher level labs may be required.
- Recognized subspecies that vary in location and virulence:
- F. tularensis: distinguished by PCR and the only relatively common human pathogen.
- F. tularensis subsp. tularensis often are worse than those caused by F. tularensis subsp. holarctica
- F. novidicida and F. philomiragia
- A rare disease in humans, mostly immunocompromised.
- F. hispaniensis
- F. opportunistica
- F. salimarina
- Notes:
- Biovar tularensis (Type A), typically associated with lagomorphs (hares, rabbits, pikas)
- Biovar holarctica (B), frequently associated with rodents and aquatic environments
- Biovar mediasiatica and subspecies novicida
- Multiple other Francisella species have been isolated from animal and environmental samples.
- Biovar tularensis (Type A), typically associated with lagomorphs (hares, rabbits, pikas)
- F. tularensis: distinguished by PCR and the only relatively common human pathogen.
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Last updated: March 18, 2023
Citation
Fabre, Valeria Fabre. "Francisella Tularensis." Johns Hopkins ABX Guide, The Johns Hopkins University, 2023. Pediatrics Central, peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540233/1/Francisella_tularensis.
Fabre V. Francisella tularensis. Johns Hopkins ABX Guide. The Johns Hopkins University; 2023. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540233/1/Francisella_tularensis. Accessed October 13, 2024.
Fabre, V. (2023). Francisella tularensis. In Johns Hopkins ABX Guide. The Johns Hopkins University. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540233/1/Francisella_tularensis
Fabre V. Francisella Tularensis [Internet]. In: Johns Hopkins ABX Guide. The Johns Hopkins University; 2023. [cited 2024 October 13]. Available from: https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540233/1/Francisella_tularensis.
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