Francisella opportunistica sp. nov., isolated from human blood and cerebrospinal fluid

Two isolates of a Gram-negative, non-spore-forming coccobacillus cultured from the blood and cerebrospinal fluid of immunocompromised patients in the United States were described previously. Biochemical and phylogenetic analyses revealed that they belong to a novel species within the Francisella genus. Here we describe a third isolate of this species, recovered from blood of a febrile patient with renal failure, and formally name the Francisella species. Whole genome comparisons indicated the three isolates display greater than 99.9% average nucleotide identity (ANI) to each other and are most closely related to the tick endosymbiont F. persica. with only 88.6-88.8% ANI to the type strain of F persica. Based on biochemical, metabolic and genomic comparisons, we propose that these three isolates should be recognized as Francisella opportunistica sp. nov, with the type strain of the species. PA05-1188(T), available through the Deutsche Sammlung von Mikroorganismen and Zellkulturen (DSM 107100) and the American Type Culture Collection (ATCC BAA-2974).