Influence of oral inoculation with plasmid-free human Escherichia coli on the frequency of diarrhea during the first year of life in human newborns

Background: This study was carried out to determine whether early inoculation of the plasmid-free human Escherichia coli into human newborns would reduce the frequency of acute diarrhea during a 1-year period. The plasmid-free E. coli strain isolated from the fecal microbiota of a healthy adult was nontoxigenic in vivo and in vitro and sensitive to all usual antibiotics. Methods: In the experimental group, 51 healthy newborns were inoculated orally with 10(6) viable cells of the bacteria within 2 hours after birth. In the control group, the same number of newborns received the heat-killed bacteria. The clinical trial was double blind, and the newborns were randomly assigned to the experimental and control groups. Results: Six months and I year after bacterial inoculation, infants in the experimental group showed a higher mean body weight (7.59 +/- 1.15 kg and 9.88 +/- 1.31 kg, respectively; P < 0.05) when compared with the control group (7.03 +/- 1.09 kg and 8.92 +/- 1.38 kg, respectively). At the end of the clinical trial, 48% (23/48) of the infants in the experimental group had shown at least one diarrhea episode during the I-year period, as opposed to 71% (34/48) in the control group. These values were significantly different (P = 0.037), showing a 32.3% protective effect of inoculation. Conclusions: The present study shows that protection against diarrhea was obtained by oral inoculation with a single dose of plasmid-free human E. coli soon after birth.