Bacterial adherence to endothelial cells from rat heart, with special regard to alpha-hemolytic streptococci

Endothelial cells were prepared from rat heart, and the ability of various bacterial species to adhere to these cells was investigated, with special regard to alpha-hemolytic streptococci. The endothelial cells were identified by morphology and by the presence of F VIII antigen. Seventeen bacterial strains representing various species were used in the in vitro adherence tests; 10 strains represented various strains of alpha-hemolytic streptococci, 5 of which were isolated from patients with infective endocarditis and 5 from the throats of healthy individuals; 2 were Neisseria meningitidis, 2 N. gonorrhoeae, 2 S. aureus and 1 E. coli. The highest adherence rate was found for alpha-hemolytic streptococci isolated from patients with infective endocarditis. The difference compared to carrier strains of alpha-hemolytic streptococci and to the other tested strains was statistically highly significant.