a1 Department of Pediatrics, Danderyd Hospital, S-182 88 Danderyd, Sweden
a2 Department of Bacteriology, National Bacteriology Laboratory, Stockholm, Sweden
A prospective study of faecal colonization with P-fimbriated Escherichia coli between 0 and 18 months of ago was conducted in 751 healthy infants. The influence of breast-feeding and treatment with antibiotics on this colonization was studied. Colonization with P-fimbriatcd E. coli increased with age from 10% at 6 days to 30% at 18 months of ago (P < 0·01). Breast-feeding influenced colonization at 6 weeks of age when breast-fed children harboured fewer bacterial species (P < 0·001) and fewer P-fimbriated E. coli (P = 0·06) than bottle-fed infants. Treatment with antibiotics increased the colonization rate with P-fimbriatcd E. coli at the age of 11 months (P < 0·05). However, this was not true for treatment with ampicillin, which increased colonization rate with Gram-negative species other than E. coli (P < 0·05). Fifty per cent (378) of all children were colonized and a quarter (183) had pure cultures of P-fimbriatcd E. coli in at least one faecal sample. The clinical importance of this colonization remains to be shown.
(Accepted November 16 1987)