[Difference of host response in identical toxin-produced Staphylococcus aureus-injected mice]

Biological activities of two strains of Staphylococcus aureus (S. aureus), KU-1-06-37 and KU-1-12-44, which produce enterotoxin type C, TSST-1 and alpha-toxin were examined using Std:ddY strain mice. These two strains were found to be different in lethality, ratio of weight loss, induction of leukopenia, adhesion to surrounding organs and clearance period of bacterial cells from the liver, kidney and spleen within 24 hrs after intraperitoneal injection in the mice. All of them were weak or fast in KU-1-12-44 injected mice. Serum amyloid A on all the KU-1-06-37 and KU-1-12-44 injected mice rose within 5 hr to 18 hr. However, this concentration of KU-1-12-44 injected mice was about 40% lower compared with that of KU-1-06-37 injected mice at 21 hr. On the other hand, ability of bacterial adhesion to established cell lines, Vero and HeLa cells, was tested in vitro. Percentage adhesion of KU-1-06-37 was high to both cells, but that of KU-1-12-44 was high to Vero cells and was low to HeLa cells. Adhesion of KU-1-06-37 to HeLa cells that were treated with lipoteichoic acid was about 40% inhibition compared with untreated cells, although that of KU-1-12-44 to them was inhibited only 9%. As the results, identical toxin-produced KU-1-06-37 and KU-1-12-44 showed different biological activities in vivo and in vitro. Not only toxin production but also adhesion to cells or organs in mice may contribute to S. aureus virulence to the host.