Francisella tularensis is a
pathogenic species of
Gram-negative,
rod-shaped coccobacillus, an
aerobe bacterium. It is non-spore forming, non-motile and the causative agent of
tularemia, the pneumonic form of which is often lethal without treatment. It is a fastidious, facultative
intracellular bacterium which requires
cysteine for growth. Due to its low infectious dose, ease of spread by aerosol, and high
virulence,
F. tularensis is classified as a
Tier 1 Select Agent by the U.S. government, along with other potential agents of bioterrorism such as
Yersinia pestis, Bacillus anthracis and
Ebola virus.