Adherence properties of enterotoxigenic Escherichia coli (ETEC) isolated in the Tel-Aviv area.

We tested the expression of adherence properties of Enterotoxigenic Escherichia coli (ETEC) strains isolated in the Tel-Aviv area by examining their hemagglutination (HA) patterns, and their adherence in vitro to Human Kidney (Huk) cells in tissue culture. Hemagglutination patterns of 75 ETEC and 63 non-ETEC strains isolated from stool samples were examined. The strains were tested for mannose-sensitive hemagglutination (MSHA) capacity of guinea pig erythrocytes, and for mannose-resistant hemagglutination (MRHA) capacity of human and bovine erythrocytes. The distribution of HA patterns among groups of non-ETEC and ETEC predominating strains was compared. (The latter contained strains which were isolated from 21 stool samples as at least two identical isolates.) The ratio of strains containing at least one of MS and MR hemagglutinins was found to be significantly higher in the group of ETEC-predominating strains than in non-ETEC. Eleven of 21 ETEC- predominating strains showed MRHA, and in ten of them Colonization Factor Antigens, CFA/I or CFA/II were identified by HA inhibition and agglutination using specific antisera. The influence of the bacterial culture conditions on expression of MSHA and MRHA and on adherence capacity of the bacteria to HuK cell culture was tested. Results show that ETEC strains exhibited a wide range of phenotypic manifestations of type and strength of adhesions. The variations depend not only on strain but also on culture condition and the type of target cells used in the experiments. In some strains a correlation was observed in the expression of adhesions using various experimental models; in others this correlation was not found. These findings suggest that, although CFAs were relatively common among ETEC-predominating strains isolated in the Tel-Aviv area, other adhesions could be involved in the pathogenic process.