Two recent developments have stimulated renewed interest in E, scherichia coli infections of man. In the first place, through the important investigations of Kauffmann and his associates (1, 2) extensive knowledge has been gained on the antigenic pattern of this species. The discovery by Kauffmann of antigens as inhibitors of O agglutinability and the identification of the various antigens (the somatic O antigens, the envelope or surface L and B antigens, the capsular A antigens, and the flagellar H antigens) have brought order to the serological grouping and typing of E. coli and made possible studies on the relationship between antigenic types of E. coli and various infections.The second discovery of major importance is the finding of the association of two serological groups of E. coli, namely, serogroups O l l l and 055, with epidemic and sporadic diarrheal disease of infants. In 1923 and 1927, Adam (3, 4) reported on the recovery of several biochemical types of E. coli from patients with diarrheal disease. It remained for the British investigators Bray (5), Bray and Beavan (6), Giles and Sangster (7), Giles, Sangster, and Smith (8), Smith (9), as well as Taylor, Powell, and Wright (10) to establish the fact that in certain outbreaks of epidemic diarrhea two serogroups of E. coli are found in a high percentage of affected children and 0nly rarely in healthy infants, children, and adults. These two antigenic groups have been identified as serogroups O l l l and 055. The observations of these investigators have been confirmed and extended in various parts of the world, including the Scandinavian countries by Kauffmann and Dupont (11), the Netherlands by Beeuwkes, Hodenpijl, and ten Seldam (12), Germany by Braun (13), and the United States by Modica, Ferguson, and Ducey (14), Neter and Shumway (15), Neter and Webb (16), Neter, Webb, Shumway, and Murdock (17). Very recently, Orskov (18) reported on the occurrence of E. coli belonging to O-group 26 in cases of infantile diarrhea and in white scours of newborn calves. Thus it appears likely that groups other than O l l l and 055 may be associated with diarrheal disease of infants.
