Borrelia theileri

Borrelia is a genus of bacteria of the spirochete phylum. It causes Lyme disease, also called Lyme borreliosis, a zoonotic, vector-borne disease transmitted primarily by ticks and by lice, depending on the species of bacteria. The genus is named after the French biologist Amédée Borrel (1867–1936), who first documented the distinction between a species of Borrelia, B. anserina, and the other known type of spirochete at the time, Treponema pallidum. This bacterium must be viewed using dark-field microscopy, which make the cells appear white against a dark background. Borrelia species are grown in Barbour-Stoenner-Kelly (BSK) medium. Of 52 known species of Borrelia, 21 are members of the Lyme disease group, 29 belong to the relapsing fever group, and two are members of a genetically distinct third group typically found in reptiles. The Lyme disease group has been moved to their own genus, Borelliella, but this change is not yet widely accepted. This bacterium uses hard and soft ticks and lice as vectors. Testing for the presence of the bacteria in a human includes two-tiered serological testing, including immunoassays and immunoblotting. Borrelia species are members of the Spirochaetacaea family, so present the characteristic spirochete (spiral) shape. Most species are obligate anaerobes, although some are aerotolerant. Borrelia species have an outer membrane that contains a substance similar to lipopolysaccharides, an inner membrane, and a layer of peptidoglycan in a periplasmic space, which classifies them as Gram-negative. However, this result is not easily visualized using Gram staining. They are typically 20-30 μm long and 0.2-0.3 μm wide. Spirochetes move using axial filaments called endoflagella in their periplasmic space. The filaments rotate in this space, between the outer membrane and the peptidoglycan layer, propelling the bacterium forward in a corkscrew-like motion. The outer membrane of Borrelia species contains outer surface proteins (Osp) that play a role in their virulence. The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI) and the phylogeny is based on 16S rRNA-based LTP release 111 by the All-Species Living Tree Project. Notes:♦ Type strain lost or not available♠ Strains found at the NCBI, but not listed in the LSPN♥ Strains neither lodged at NCBI nor listed in the LPSN Ticks Hard ticks of the family Ixodidae are common vectors of Borellia bacteria and are the only type of ticks shown to transmit Lyme disease bacteria to humans.