New provisional serovar of Shigella boydii

Ten bacterial strains are described that give biochemical reactions characteristic of the genus Shigella but do not belong to any of the established or provisional serovars. The strains ferment mannitol and are antigenically indistinguishable. They do not possess any of the group antigens of Shigella flexneri, and it is therefore proposed that they be regarded as members of a new provisional serovar of Shigella boydii. Strain E16553 is designated as the test strain for the new serovar.