Francisella novicida

Francisella novicida
Scientific classification
Domain:	Bacteria
Phylum:	Pseudomonadota
Class:	Gammaproteobacteria
Order:	Thiotrichales
Family:	Francisellaceae
Genus:	Francisella
Species:	F. novicida
Binomial name
Francisella novicida (Larson et al. 1955) Olsufiev et al. 1959 (Approved Lists 1980)

Francisella novicida is a bacterium of the Francisellaceae family, which consist of Gram-negative pathogenic bacteria. These bacteria vary from small cocci to rod-shaped, and are most known for their intracellular parasitic capabilities. In this family, six species have been identified; however, the species F. novicida is under intense scrutiny. Though some believe it should be classified with its own species designation, others argue it should be reclassified as a subspecies under F. tularensis. If it were to be classified as a subspecies, F. novicida would join the other known subspecies including F. t. tularensis (type A) and F. t. holarctica (type B). Biochemical assays for identifying F. tularensis subtypes and strains are not ideal because the results are often non-definitive and subject to variation, therefore these assays should only be considered as supplementary tests for identification of Francisella species and subspecies.^[1][2] Several strains of F. novicida or F. novicida-like bacteria have been described, and these strains may be resolved by PCR-based methods.^[3]

Though F. novicida is considered a rare pathogen, its close relative F. tularensis is well known for causing tularemia. Unlike F. tularensis, there have been no documented cases of F. novicida or F. novicida-like strain transmission to humans through arthropod bites. The route of infection for the majority of human F. novicida or F. novicida-'like' cases is unknown, although infected water or ice have been implicated. Some of the main symptoms associated with this infection include pneumonia, muscle pain, and fever, among many others. When reported, cases of F. novicida or F. novicida-like infections are most commonly seen in immunocompromised people. Though F. novicida is rarely associated with human illness despite the close genetic relationship to F. tularensis, cases have been reported in humans in the United States. For example, one case of F. novicida involved a woman in Arizona in 2009.^[1] Additionally, in 2011, three confirmed cases of F. novicida were found in a residential facility in Louisiana. In the later case, ice was the mode of transmission; however, how the ice was originally contaminated with the F. novicida is still unknown.^[4]