The Role of Alpha Haemolysin in the Virulence of Escherichia Coli for Mice

Abstract

SUMMARY.Transfer of an Hly plasmid determining production of a haemolysin to a non-haemolytic strain of Escherichia coli increased the virulence of the strain for mice. Injections of non-toxic amounts of a haemolysin, phenylhydrazine, haemoglobin, iron or manganese salts simulated the effect of the Hly plasmid by stimulating bacterial growth. Active or passive immunisation against o! haemolysin protected mice on challenge with haemolytic E. coli by inhibiting in-vivo proliferation of the strain. Protection was eliminated by administration of iron salts at the time of challenge. The Hly plasmid probably acts as a virulence factor by enabling haemolytic strains of E. coli to obtain iron for growth from the lysed erythrocytes of infected animals.

Analysis of the Genome Structure of the Nonpathogenic Probiotic Escherichia coli Strain Nissle 1917

“…In contrast to GEI II Nissle 1917 , the pheV-associated island of strain CFT073 carries the complete hly and pap gene clusters coding for the important virulence factors alpha-hemolysin and P fimbria, respectively. These determinants, together with other putative hypothetical ORFs, represent a 30-kb region, which is presumably of crucial importance for this strain's virulence properties (12,30,31,35). Interestingly, only a fragmented pap operon is present in a similar DNA context on GEI II Nissle 1917 (Fig.…”

Escherichia coliin extra-intestinal infections

“…Isogenic Hly-bacteria were not cytotoxic (Gadeberg & 0rskov, 1984). Thus a haemolytic E. coli culture may be virulent because of a toxic effect on various cells, and in addition this effect may be strengthened because the growth of the strain is stimulated by iron made available by lysis of the erythrocytes (Linggood & Ingram, 1982;Waalwijk, MacLaren & de Graaf, 1983). See also aerobactin under the section on bacteraemia.…”

Virulence factors in Escherichia coli urinary tract infection

“…Animal Studies Hemolytic strains are more lethal than nonhemolytic strains for chicken embryos (116,173,206,275,353) and for mice or rats in models of peritonitis (116,173,175,198,275,500,603,604), respiratory infection (115,173), and hematogenous pyelonephritis (136,137,173,310,565,566,587,589,590), causing hemorrhagic lung lesions and hemoglobinuria in mice in addition to increased mortality (116,500). In mouse and rat models of ascending UTI, hemolysin production is associated with increased bladder colonization and nephropathogenicity (97,212,265,340).…”

“…These observations suggest that hemolysin promotes virulence both by providing iron for bacterial metabolism and by directly injuring host tissues. Active (310) or passive (115) immunity against hemolysin protects mice against infection with hemolytic strains. Epidemiology Expression during UTI.…”