Divisions of the so Called Flexner Group of Dysentery Bacilli.* by Wilburt C. Davison

There is considerable confusion in regard to the existence of subdivisions of the mannitol-fermenting group of dysentery bacilli. Numerous attempt~ have been made to establish subdivisions on the basis of their biological and serological characteristics (1-8). My conclusions are derived from the fermentation and agglutination reactions of 77 cultures isolated from cases of clinical dysentery in children, 12 cultures from cases of dysentery in the American Expeditionary Forces, and stock cultures of the 5 English types of Flexner bacilli. 1 By the Flexner group I refer to Gram-negative non-motile bacilli, isolated from the stools of cases of clinical dysentery and agglutinated by the patient's serum. They produce a small amount of indole, do not liquefy gelatin, fail to ferment lactose, and produce acid and no gas in dextrose and mannitol. These are the only constant cultural characteristics. I t would seem advisable to apply one name, Bacillus dysenteri~ Flexner, to this whole group. These mannitol-fermenting dysentery bacilli have been subdivided in two ways, first by fermentation tests with maltose, saccharose, dulcitol, and rhamnose, and secondly by agglutination tests with the sera of immunized rabbits.