COMPARATIVE FREQUENCY OF DETECTION OF ENTEROPATHOGENIC E. COLI, SALMONELLA AND SHIGELLA IN RECTAL SWAB CULTURES FROM INFANTS AND YOUNG CHILDREN
Authors: Cooper Merlin L. , Keller Helen M. , Walters Edward W. 
Published: December 2021

The present report supplies the details and results of a study of 2,865 patients during a period of 2 years, March 1, 1954, to March 1, 1956.
The purpose of the study was to determine the comparative frequency of isolation of Salmonella, Shigella and nine serotypes of enteropathogenic E. coli from rectal swab cultures obtained from infants and young children admitted to the Children's Hospital.
The technic for the isolation and identification of enteropathogenic E. coli is described. A diagnostic polyvalent E. coli antiserum prepared in our laboratory was very helpful in the preliminary detection of nine serotypes of enteropathogenic E. coli.
Salmonellae were isolated from 85 patients, Shigellae from 88 and one of the nine serotypes of enteropathogenic E. coli from each of 188 patients. Seventeen serotypes of Salmonella were isolated from 85 patients. Salmonella sp. (Type oranienburg) and Sal. typhimurium were isolated most frequently. Shigellae were isolated from a total of 88 patients; Sh. sonnei from 53 and five serotypes of Sh. flexneri from 35 patients. One of the nine serotypes of enteropathogenic E. coli was isolated from each of 188 patients. E. coli 055:B5 was detected in cultures from 63 patients and was detected most frequently. E. coli 0111:B4, 0126:B16 and 026:B6 were found next most frequently.
Of the 361 patients from whom Salmonella, Shigella or enteropathogenic E. coli were isolated, rectal swab cultures were obtained at the time of admission from 317. Of these, 287 (91%) were positive.
The incidence of diarrhea in the three groups was comparable: 95% of the patients from whom Salmonellae were isolated, 98% of patients from whom Shigellae were isolated and 92% of patients harboring enteropathogenic E. coli.
Infections due to Salmonella or enteropathogenic E. coli were more frequent in the first year of life and infections due to Shigella occurred more frequently in the second year of life. The majority of patients with diarrhea and with rectal swab cultures negative for Salmonella, Shigella and enteropathogenic E. coli were in the first year of life. The incidence of Salmonella infections did not show any seasonal predominance; the Shigella infections were most frequent in September and October and the enteropathogenic E. coli infections in November and October. The highest incidence of diarrheal infections among patients whose rectal swab cultures were negative for these three groups of bacteria occurred in December and January of each of the 2 years of this study.
The incidence of enteropathogenic E. coli infections exceeded those due to Shigella or Salmonella during 15 of the 24 months of this study. Sporadic infections due to these three groups of bacteria occurred throughout the 2-year period.
Successive and/or multiple infections with Salmonella, Shigella or enteropathogenic E. coli occurred in 15 paients. Infection with one serotype of enteropathogenic E. coli did not protect seven patients from subsequent infection with another serotype.
The convalescent carrier rate was 36.6% for the patients with Salmonella infections, 2.6% for those with Shigella infections and 8.3% for those from whom enteropathogenic E. coli had been isolated.
The mortality rate was 1.2% among patients with Salmonella infections and 1.6% among the patients from whom enteropathogenic E. coli had been isolated. None of the patients with Shigella infections died.
The large number of patients, 889, with diarrhea and with rectal swab cultures negative for Salmonella, Shigella and enteropathogenic E. coli indicates a need for continued investigation into the etiology of diarrhea in infants and young children.