ALPHA-HEMOLYSIN - AN ADDITIVE VIRULENCE FACTOR IN ESCHERICHIA-COLI

  • 1 January 1980
    • journal article
    • research article
    • Vol. 27  (4) , 333-342
Abstract
Hemolytic (Hly) E. coli, including human intestinal and extraintestinal as well as porcine enterotoxigenic and edema disease isolates, and Proteus morganii strains were studied for their virulence. Hly+ wild type strains and Hly+ transconjugants were more virulent than Hly+ derivatives as shown in mice and chick embryos. This enhanced virulence was associated with diffusible .alpha.-hemolysin production because clones producing only non-diffusible .beta.-hemolysin behaved as non-hemolytic ones. Hemorrhagic lung symptoms and hemoglobinuria were frequently observed after parenteral challenge of mice with .alpha.-hemolytic clones. Though the Hly- clone exhibited a high resistance against blood clearance, the number of circulating .alpha.-hemolytic bacteria was significantly higher. A causal connection between this phenomenon and the leukocidin activity of .alpha.-hemolysin is suggested.