Several septicemic Escherichia coil O78 strains, isolated from differe
nt sources, were characterized phenotypically and genotypically. Two a
vian isolates, one of which is known to carry the AC/I fimbriae, hybri
dized with the sfa determinant in colony dot-blot assay. Southern hybr
idizations with specific sfa probes, following pulsed-field gel electr
ophoresis (PFGE), showed positive hybridization to the same fragment i
n each of these strains. Determination of the N-terminal amino acid se
quence of the AC/I major subunit gene revealed high similarity to the
sequence of the SfaA-II protein. These data suggest that the adhesin g
ene cluster, coding for AC/I fimbriae, belongs to the S-fimbrial adhes
in family.