S-fimbriated Escherichia coli, which cause sepsis and meningitis in the newborn, bind to sialic acid-containing glycoprotein structures on the surface of human buccal epithelial cells. The dependence of this binding on host age was examined. S-fimbriated E. coli adhered in comparable numbers to cells in newborns, infants, children and adults (23.0 +/- 8.6; 23.1 +/- 11.5; 24.7 +/- 7.9; 28.9 +/- 8.8). Thus, the increased susceptibility of neonates to infections caused by S-fimbriated E. coli cannot be explained by enhanced adhesion to epithelial cells.