HUMAN NEUTROPHIL OXIDATIVE RESPONSE AND PHAGOCYTIC KILLING OF CLINICAL AND LABORATORY STRAINS OF ENTEROCOCCUS-FAECALIS

Many clinical isolates of Enterococcus faecalis produce a hemolysin/ba cteriocin that is plasmid mediated. Recent human epidemiologic studies and animal research suggest that this hemolysin/bacteriocin may enhan ce the pathogenicity of hemolysin-producing enterococci compared with non-hemolysin-producing strains. These studies determined that clinica l strains that produce hemolysin/bacteriocin differed from non-hemolys in-producing clinical and laboratory strains in their ability to induc e the production of reactive oxygen intermediates in human peripheral blood neutrophils and in their susceptibility to phagocytic killing in vitro. The induction of superoxide anion generation by neutrophils wa s demonstrated to be directly proportional to the presence of the hemo lysin/bacteriocin plasmid and was transferable to a non-hemolysin-prod ucing laboratory strain by transconjugation. The presence of the plasm id, however, did not effect killing by phagocytic cells in vitro. It i s proposed that hemolysin/bacteriocin-producing strains of enterococcu s may be more pathogenic due to reactive oxygen product-induced tissue injury in vitro.