Flavobacterium columnare

Flavobacterium columnare is a thin Gram-negative rod bacterium of the genus Flavobacterium. The name derives from the way in which the organism grows in rhizoid columnar formations.^[2]

Flavobacterium columnare
Scientific classification
Domain:	Bacteria
Kingdom:	Pseudomonadati
Phylum:	Bacteroidota
Class:	Flavobacteriia
Order:	Flavobacteriales
Family:	Flavobacteriaceae
Genus:	Flavobacterium
Species:	F. columnare
Binomial name
Flavobacterium columnare (Bernardet and Grimont 1989) Bernardet et al. 1996[1]

The species was first described by Davis (1922), and the name was validated by Bernardet and Grimont (1989).^[3]

Flavobacterium columnare can be identified in the laboratory by a five-step method that demonstrates:

1. the ability to grow on a medium containing neomycin and polymyxin B
2. production of yellow pigmented rhizoid (root-like in appearance) colonies
3. production of a gelatin-degrading enzyme
4. binding of Congo red dye to the colony
5. production of a chondroitin sulfate-degrading enzyme^[4]

The species has been known previously as Flexibacter columnaris, Bacillus columnaris, and Cytophaga columnaris.

Flavobacterium columnare is one of the oldest known diseases among warm-water fish, and manifests itself as an infection commonly known as columnaris. Infections are the second leading cause of mortality in pond raised catfish in the southeastern United States.^[4] Early treatment with potassium permanganate has been shown to increase survival rate, although the difference was not statistically significant.^[5]