The genus Flavobacterium has undergone several taxonomic shifts since it was created nearly 100 years ago, beginning with the separation of a number of pathogenic species into a new genus, Chryseobacterium.¹ Further reclassification occurred with the naming of genus Elizabethkingia into which several Chryseobacterium were moved, including the pathogenic species E. meningoseptica (formerly Chryseobacterium meningosepticum; originally Flavobacterium meningosepticum) and E. miricola.² Recent genomic analysis of unidentified isolates resembling the two genera, as well as a review of the four genomospecies of Elizabethkingia, have resulted in the naming of new, novel species of Chryseobacterium and Elizabethkingia.^1,2 Chryseobacterium underwent an even more recent taxonomic reorganization following the comparison of amino acid identity among type strains, leading to the division of the Chryseobacterium genus into four different genera with Epilithonimonas, Kaistella and Halpernia gen. nov.³ Many of these reclassifications involved the renaming of historical isolates and type strains, many of which were recently deposited to BEI Resources.

Chryseobacterium spp. and Elizabethkingia spp. are Gram-negative environmental bacteria found in soil and water worldwide. Though infections in humans are rare, an average of 5-to-10 cases occur per state each year in the United States, often resulting in small healthcare-related outbreaks, such as the E. anopheles outbreak in Wisconsin in 2016.⁴

References:

1. Holmes, B., A. G. Steigerwalt and A. C. Nicholson. “DNA-DNA Hybridization Study of Strains of Chryseobacterium, Elizabethkingia and Empedobacter and of Other Usually Indole-Producing Non-Fermenters of CDC Groups IIc, IIe, IIh and IIi, Mostly from Human Clinical Sources, and Proposals of Chryseobacterium bernardetii sp. nov., Chryseobacterium carnis sp. nov., Chryseobacterium lactis sp. nov., Chryseobacterium nakagawai sp. nov. and Chryseobacterium taklimakanense comb. nov.” Int. J. Syst. Evol. Microbiol. 63 (2013):  4639-4662.  PubMed:  23934253.
2. Nicholson, A. C., et al. “Revisiting the Taxonomy of the Genus Elizabethkingia Using Whole-Genome Sequencing, Optical Mapping, and MALDI-TOF, Along with Proposal of Three Novel Elizabethkingia species: Elizabethkingia bruuniana sp. nov., Elizabethkingia ursingii sp. nov., and Elizabethkingia occulta sp. nov.” Antonie Van Leeuwenhoek 111 (2018):  55-72.  PubMed:  28856455.
3. Nicholson, A. C., et al. “Division of the genus Chryseobacterium: Observation of Discontinuities in Amino Acid Identity Values, a Possible Consequence of Major Extinction Events, Guides Transfer of Nine Species to the Genus Epilithonimonas, Eleven Species to the Genus Kaistella, and Three Species to the Genus Halpernia gen. nov., with Description of Kaistella daneshvariae sp. nov. and Epilithonimonas vandammei sp. nov. Derived from Clinical Specimens.” Int. J. Syst. Evol. Microbiol. 70 (2020):  4432-4450.  PubMed:  32735208.
4. “Elizabethkingia.”  Centers for Disease Control and Prevention, U.S. Department of Health and Human Services,  https://www.cdc.gov/elizabethkingia/index.html.

Image:  Transmission electron microscopic image of Elizabethkingia anophelis bacteria (CDC/Cynthia Goldsmith)