O, K, H and fimbrial antigens in Escherichia coli serotypes associated with pyelonephritis and cystitis.

O:K:H serotype determination of 267 E. coli strains from patients with pyelonephritis or cystitis led us to tentatively consider some O:K:H types, e.g. O6:K2:H1 as pyelonephritis and e.g. O6:K13:H1 as cystitis associated types. By means of crossed immunoelectrophoresis (CIE) several strains of such special O:K:H serotypes were examined for presence of the previously described fimbrial antigens, F7 and F8. Three new F antigens were designated F10, F11 and F12. The fimbrial structures of these antigens were demonstrated by immunoelectron microscopy (IEM). Based on the haemagglutinating (HA) capacity of the strains it was possible to separate differently fimbriated organisms of the same strain. The bacteria which agglutinate human erythrocytes could be absorbed out of the mixture when the erythrocytes were removed by sedimentation. When the bacteria in the supernatant no longer agglutinated human erythrocytes they were regarded as HA absorbed and were compared with non-HA absorbed bacteria for their ability to attach to epithelial cells from the urinary tract. Hence, it was concluded that F7, F8 and F10 caused haemagglutination and were responsible for the attachment to urinary epithelial cells, while the fimbriae antigenically termed pseudotype 1 did not induce haemagglutination and played little or no role for the attachment to this kind of epithelial cells.