Adsorption to Al(OH), gel of Escherichia coli is correlated with O and K antigens and with type of extraintestinal infection.

Living suspensions of 89 Escherichia coli strains were tested for adsorption to Al(OH)3 gel in the presence of phosphate ions. On the basis of AC50 (phosphate molarity inhibiting 50% adsorption of the strain examined), E. coli strains could be classified into two main groups. Forty-three strains belonged to group 1 (AC50, 0.01-0.04), and 42 of them fell into serogroups O1, O2, O5, O7, O18ac, O83 or were spontaneously agglutinable. One strain in group 1 was exceptional as it had antigen O4. Of these 43 strains 33 had K antigen K1. Serogroup distribution of 46 group 2 strains (AC50, 0.001-0.009) was O2, O4, O6, O18ac, O75 and O78; 20 out of 46 possessed antigen K5. No correlation existed between H antigens or haemagglutinating capacity and AC50 of the strains. A close correlation was shown between AC50 pattern and the two main pathogenecity groups (i.e. "newborns' meningitis" and "sepsis and organotropic diseases") on one hand and between AC50 pattern and O, K serotypes on the other. The findings indicate that these E. coli strains with identical markers had a clonal connection.