Gal-Gal Binding and Hemolysin Phenotypes and Genotypes Associated with UropathogenicEscherichia coli

Abstract

To determine whether uropathogenic strains of Escherichia coli exhibit a distinctive constellation of phenotypes, we examined 44 urinary isolates from women with radiologically normal urinary tracts and pyelonephritis, cystitis, or asymptomatic bacteriuria and 73 fecal isolates from healthy control subjects. The strains were characterized by their O serogroup, by their binding specificity (as determined by adhesins), and by their production of hemolysin and colicin V. In addition, the strains were assessed for homologous gene sequences by means of DNA-hybridization probes prepared from cistrons that encode hemolysin and the Gal-Gal binding adhesin--two determinants of virulence, which cause tissue injury and promote bacterial colonization of uroepithelia, respectively. In contrast to most isolates from normal feces and from the urine of patients with asymptomatic bacteriuria, pyelonephritis strains belong to a small number of O serogroups; all express the Gal--Gal binding adhesin and 75 per cent are hemolytic. A gene probe for the Gal--Gal binding adhesin, derived from the chromosome of one strain from a patient with pyelonephritis, hybridized with the DNA of all other pyelonephritis strains. The probe for the hemolysin gene hybridized with DNA from all other hemolytic strains. These data indicate that most cases of pyelonephritis are due to a small number of pathogenic clones that express critical determinants of virulence, and that the nucleotide sequences for hemolysin and the Gal--Gal binding adhesin in heterologous strains share homology. We are tempted to speculate that the gene products of these shared regions of the genome might form the basis for a vaccine against pyelonephritis.

Genetic structures of the B2 and B1 Escherichia coli strains responsible for extra-intestinal infections

“…The most virulent B, clusters are the 0 4 and 0 6 groups (clusters B and D), where the majority of strains produce the three virulence factors. The prevalence of these two serogroups in the strains responsible for septicaemia and their frequent production of virulence factors has been reported previously (Cherifi et al, 1990;Low et al, 1984;O'Hanley et al, 1985;Caprioli et al, 1987). The present work indicates that these strains, which all have few ribotypes (h,-b, and h,-b,), are genotypically homogeneous.…”

Lack of association ofEscherichia coliexhibiting both mannose-resistant haemagglutination and diffuse adherence to Hep-2 cells with acute diarrhoea in children

“…Our results are in accordance with these findings and indicate that they could be extended to faecal E. coli. We could not confirm the observation that (pyelonephritogenic) strains expressing MRHA, haemolysis and P fimbriae are frequently associated with 0 antigens 0 1, 0 4, 0 6, 0 16, 0 18, 0 25, O 50, and 0 75 (12,22), since with the available antisera (for all antigens mentioned above, except 0 16 and 0 50) the serogroup of only 6 of all our intestinal MRHA + strains was determined (5 belonged to 0 6 and 1 to 0 4 serogroup).…”

“…P fimbriae and haemolysin synthesis are often expressed en bloc in uropathogenic strains as a consequence of close linkage of their genetic determinants (21)(22)(23). In these isolates the association of aerobactin-production and P fimbriae-expression was also found (21,24).…”

Urinary Tract Immunology

“…The poreforming toxin alpha-hemolysin (HlyA) and P fimbriae are proposed minimal factors required for colonization of and dissemination from the kidney (132). P fimbriae are adherence organelles that play a role in kidney colonization in mice and humans (133). There are convincing data using both murine (132) and primate models (134) that vaccination against P fimbriae or HlyA prevents renal colonization and damage.…”