[Maternal lactation. II. Intestinal colonization in breast fed newborn infants].

Twenty-three low birth weight infants were studied to establish the role that breast milk plays in the intestinal colonization of the preterm infant, and in the control of epidemic diarrhea due to enteropathogenic E. coli, in nurseries. Twelve of these case were fed breast milk in bottles, and eleven with "humanized" powder cow's milk (NAN M.R.). Bacteriologic studies of feces were performed daily during the first 18 days of life. In 5 cases given breast milk, and in 8 receiving cow's milk, Staphylococcus aureus was isolated. Enteropathogenic E. coli was found in 3 cases with breast milk and in 6 with cow's milk. The finding of other non-pathogenic strains, was similar for both groups, except in the case of Proteus, that was found in 10 cases with breast milk, and in only 3 cases with cow's milk. Breast milk was unable to avoid the colonization by E. coli and in one case, was unable to eradicate this germ. None of the cases fed breast milk had diarrhea, including the three cases with E. coli. In another group, 4 cases developed severe acute diarrhea, due to enteropathogenic E. coli followed by 2 deaths. The results seem to point out that although colonization by enteropathogenic strains of E. coli is not completely avoided, these strains do not cause disease when these infants are fed breast milk.