NC_010660:86445 Shigella boydii CDC 3083-94 plasmid pBS512_211, complete sequence
Host Lineage: Shigella boydii; Shigella; Enterobacteriaceae; Enterobacteriales; Proteobacteria; Bacteria
General Information: This strain (strain BS512; serotype 18) was originally isolated from a 12-year-old boy in Arizona, USA by Dr. Nancy Stockbine. It is a member of Group 1 as determined by limited sequence analysis and can invade HeLa cells. Pathogenicity and virulence have been verified during in vitro experimentation, and multiple plasmids are present in this strain. This genus is named for the Japanese scientist (Shiga) who first discovered these organisms in the 1890s. They are closely related to the Escherichia group, and may be considered the same species. These organisms are human-specific pathogens that are transmitted via contaminated food and water and are the leading causes of endemic bacillary dysentery, causing over 160 million cases of infection and 1 million deaths yearly worldwide. The bacteria infect the epithelial lining of the colon, causing acute inflammation by entering the host cell cytoplasm and spreading intercellularly. Shigella spp. are extremely virulent organisms that can cause an active infection after a very low exposure. Both the type III secretion system, which delivers effector molecules into the host cell, and some of the translocated effectors such as the invasion plasmid antigens (Ipas), are encoded on the plasmid. The bacterium produces a surface protein that localizes to one pole of the cell (IcsA) which binds to and promotes actin polymerization, resulting in movement of the bacterium through the cell cytoplasm, and eventually to neighboring cells, which results in inflammatory destruction of the mucosal lining. This species is uncommon except in India, where it was first isolated. Progression to clinical dysentery occurs in most patients infected with this organism.