[The effect of previous antibiotherapy on the colonization of an Escherichia coli strain sensitive to antibiotics in the digestive tract of hospitalized children].

The administration of the Escherichia coli (az) strain has already been used successfully to protect premature infants against intestinal colonization by nosocomial strains of antibiotic resistant enteric organisms. The purpose of the present study was to assess the protective value of this strain in older full term babies after cessation of an antibiotics treatment. Two groups of children treated with antibiotics of respectively 8-90 days and 3-12 months of age were studied and compared to two control groups of untreated children. In both groups of children, the implantation of E. coli az was higher in treated than in untreated subjects. The group of younger children was significantly less colonized by antibiotic resistant hospital acquired enteric organisms, whereas in 3-12 months old children non protective effect of E. coli az was recorded. Therefore, the antagonistic effect of the strain studied appeared as age dependent.