Francisellaceae

Francisellaceae is a family of bacteria within the order Francisellales, class Gammaproteobacteria. This family is characterized by its members' ability to cause Francisellosis, a bacterial infection that primarily affects humans. The genus Francisella is the type genus of this family, with Francisella tularensis being the most well-known species. F. tularensis is the etiological agent of tularemia, a zoonotic disease that can be transmitted to humans through contact with infected animals or their secretions.

Francisellaceae are Gram-negative, facultatively anaerobic, and rod-shaped bacteria. They are motile, with a single polar flagellum, and are capable of forming spores. The family is further divided into two genera: Francisella and Allofrancisella. Allofrancisella is a recently described genus that includes species previously classified under Francisella.

The genus Francisella includes several species, with F. tularensis being the most significant from a medical perspective. Other species, such as F. noatunensis and F. philomiragia, have been identified but are less commonly associated with human disease. The genus Allofrancisella includes species like A. amazonensis and A. magei, which have been isolated from various environmental sources.

Francisellaceae are typically cultured on selective media, such as cysteine-heart agar, to facilitate their isolation and identification. The family's members are known for their ability to survive in harsh environmental conditions, which contributes to their persistence and potential for causing disease.