Augmented production of extracellular superoxide by blood isolates of Enterococcus faecalis

J Infect Dis. 1996 Mar;173(3):743-6. doi: 10.1093/infdis/173.3.743.


To assess the frequency of extracellular superoxide (O-2) production by enterococci, multiple species were surveyed in a whole organism assay for their ability to reduce ferricytochrome c in a superoxide dismutase-inhibitable fashion. For stool and clinical enterococcal isolates and 12 type strains, only Enterococcus faecalis (87/91 isolates and ATCC 19433), Enterococcus faecium (5/13 isolates), Enterococcus casseliflavus (ATCC 25778), and Enterococcus gallinarum (ATCC 35038) produced extracellular O-2. Among 106 strains comprising 13 species of enteric gram-negative bacilli and gram-positive cocci, only Lactococcus lactis subspecies lactis produced extracellular O-2. Mean (+/-SE) rates of extracellular O-2 production in vitro by E . faecalis for isolates associated with bacteremia and endocarditis and for isolates from stool were 2.4+/-0.2, 1.9+/-0.2, 1.5+/-0.3 nmol of O-2 min(-1) 10(9) cfu(-1), respectively (P=.025, analysis of variance), suggesting an association between invasiveness and extracellular O-2 production.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacteremia / microbiology*
  • Endocarditis, Bacterial / microbiology
  • Enterococcus faecalis / isolation & purification
  • Enterococcus faecalis / metabolism*
  • Enterococcus faecalis / pathogenicity
  • Extracellular Space / metabolism
  • Feces / microbiology
  • Gram-Positive Bacterial Infections / microbiology*
  • Humans
  • In Vitro Techniques
  • Lactococcus lactis / metabolism
  • Pseudomonas Infections / microbiology
  • Pseudomonas aeruginosa / isolation & purification
  • Pseudomonas aeruginosa / metabolism
  • Superoxides / metabolism*
  • Virulence


  • Superoxides