Virulence of Escherichia coli strains in relation to their hemolysin formation, mannose-resistant hemagglutination, hydroxamate production, K 1-antigen and the plasmid profile in patients with chronic pyelonephritis.

Microorganisms initiating infections of the kidneys and the upper urinary tract are characterized by specific properties. In 96 patients with non-obstructive chronic pyelonephritis, Escherichia coli strains were isolated and their virulence properties studied. Most frequently hemolysin formation and mannose-resistant hemagglutination (n = 39/40%), less frequently the ability to produce hydroxamate/aerobactin (n = 18/19%) and the K 1-antigen (n = 13/14%) were detected. In 34 E. coli strains (35%) two and more virulence factors were found. A statistically significant correlation exists between mannose-resistant hemagglutination (evidence of P- and F7-F14 fimbriae) and hemolysin formation on the one hand and hydroxamate production and K 1-antigen on the other (confidence intervals are 0.56-0.75 and 0.75-0.89, respectively). Disease activity and pathogenicity of E. coli strains showed a statistically significant association (chi 2-value, DF 1: hemolysin 29.5, mannose-resistant hemagglutination 17.1, K 1-antigen 4.8, hydroxamate 0.5). The analysis of the plasmid profile yielded species in molecular weight range from 0-170 Md. A correlation between single virulence features and certain plasmid combinations failed to be demonstrated. The results revealed a close connection between certain virulence properties of E. coli strains and a specific uropathogenicity. The clinical significance of this observation should be further elucidated.