Epidemiological aspects of P-fimbriated Escherichia coli. IV. Extraintestinal E. coli infections before the age of one year and their relation to fecal colonization with P-fimbriated E. coli.

In two retrospective studies we have found outbreaks of E. coli pyelonephritis and septicemia to be due to nosocomial spread and fecal colonization with virulent E. coli strains in the neonatal ward of Danderyd Hospital. The incidence of extraintestinal E. coli infections before the age of one year was therefore prospectively studied in all children born at Danderyd Hospital during two and a half years (n = 7963). The number of infections was correlated to the previous fecal colonization with P-fimbriated E. coli. During this study we found no outbreaks of E. coli infections. The incidence of E. coli pyelonephritis before the age of one year was 0.6-0.7%, which we propose to be a baseline incidence. This corresponds well with the low incidence of fecal colonization with P-fimbriated E. coli found among these children. Fecal colonization with P-fimbriated E. coli during this non-epidemic period had no predictive value for the individual child for the later development of pyelonephritis.