[The effect of adherence on virulence of uropathogenic strains of Escherichia coli].

Bacterial adherence is an extremely important process in the initiation of many infections. After the successful colonization other factors of bacterial virulence produce inflammation and damage of the tissue. A close contact between bacterial and host cells, which is mediated by adherence, makes bacterial antigens better presented. In this paper correlation between the adhesin type of uropathogenic strains of Escherichia coli (UPEC), serogroup and production of hemolysin was investigated. A total of 160 Escherichia coli strains isolated from urine with significant bacteriuria (i.e. 10(5) or more organisms per ml) were analyzed. Bacterial adhesins were determined by hemagglutination and hemagglutination-inhibition tests. Serogroups were determined by standardized method, and production of hemolysin was estimated semiquantitatively using original method. P-fimbriated strains produced high amount of hemolysin, in contrast, to often nonhemolytic strains in which some other adhesins were identified (chi 2 = 50.33; p < 0.01). P-fimbriae were present mostly on strains of serogroups 06 and 02. Production of hemolysin is an important factor of UPEC virulence. Lower concentrations cause release of inflammatory mediators, and higher concentrations are cytotoxic. It also seems that lipid A, an integral part of the cell wall lipopolysaccharide, influences on induction of inflammation and aggregation of leukocytes.