Virulence factors of Escherichia coli. II. Antigens O4, O6 and O18, haemolysin production and mannose resistant haemagglutinating capacity are closely associated.

Escherichia coli strains isolated from a variety of human samples were examined for alpha haemolysin (Hly) production. A total of 1156 strains was compared for incidence of Hly positivity, and the capacity of mannose resistant haemagglutinating activity of human erythrocytes (MRHA). Incidence of Hly production in serogroups O4, O6 and O18ac was significantly higher than in other ones (70.1% vs. 18.7%), independently of the origin of strains; 78% of Hly+ strains belonging to serogroups O4, O6, O18 was MRHA+, too. The marked correlation between Hly positivity, MRHA activity and these serogroups suggested that in serogroup O4, O18 and in a lesser degree O6, genetic informations concerning O antigen, MRHA and Hly are linked in the chromosome.