The Relationship of Shigella Dispar to Certain Coliform Bacteria.

This report deals with serological and biochemical relationships between members of the genus Escherichia and Escherichia-like paracolon bacteria and the microorganisms that are usually classified as Shigella di8par. These studies are part of an investigation on the interrelationships within the family Enterobacteriaceae that was started in 1942 and which is still in progress. Shigella ceylonensis A and Shigella ceylonensis B were isolated by Castellani in 1904 and 1905. In 1912 this investigator described another bacterium that was later named ShigeUa madampensis. S. ceylonensis A was subsequently found to be the same as the microorganism described by Duval (1904), Sonne (1915), and d'Herelle (1916). This species is now known as Shigella sonnei. (For references to these earlier publications, see Soule and Heyman, 1933). Andrewes (1918) studied a group of Shigella and Shigella-like microorganisms and proposed a new species, "B. dispar," in which were placed all the lactose-positive shigellae "... without prejudice as to the number of types or species which may thus be included." Levine (1920) reported that the indole-negative "dispars" of Andrewes were culturally the same as the Sonne-Duval bacillus (Shigella sonnei). The work of Carpenter and Stuart (1946) and of Carpenter (1943) did much toward ending the confusion extant in the literature pertaining to the indolepositive, lactose-positive shigellae. Their investigations showed that S. madampensis and S. ceylonensis B were composed of a group of closely related microorganisms. Carpenter and Stuart used the name S. dispar for this group of bacteria and included S. dispar I (S. madampensis) and S. dispar II (S. ceylonen8is B) in it. They reported three serotypes of S. dispar II (IIa, IIb, and IIc) and Carpenter (personal communication, 1946) added a fourth, S. dispar IId. The various types of S. dispar were kindly supplied by Dr. Carpenter and the results reported here confirm the relationships enumerated by Carpenter and Stuart (1946) in all important aspects.