Francisella tularensis — Key Characteristics
F. tularensis is highly infectious! Once this organism is suspected on the basis of clinical and/or laboratory information, do not perform additional testing. Send the isolate to the South Dakota State Laboratory for identification.
- Gram-negative, tiny pleomorphic, poorly staining, coccobacillus.
- Sheep blood agar – grows poorly with very tiny colonies.
- Chocolate agar (cystine enriched) – grows slowly.
- Oxidase negative.
- Urease negative.
- Beta-lactamase positive.
- X and V factors are not required.
- Not in the database of most commercial systems.
- Caution: This organism looks like Haemophilus, but do not smell it. F. tularensis has been reported to cross intact skin. Leave lids on plates.
- H. influenzae
- H. aphrophilus
- Group IV