Preferential induction of septic arthritis and mortality by superantigen-producing staphylococci

Staphylococcal enterotoxins A through D (SEA through SED) and toxic shock syndrome toxin-1 display superantigen properties, i.e., they stimulate a great fraction of T cells expressing certain T-cell receptor V beta sequences. Using a newly established rat model of septic Staphylococcus aureus arthritis, we have recently shown that an S. aureus strain producing SEA showed marked arthritogenic properties. In the present study we decided to employ another five S. aureus strains, each one producing a distinct exotoxin. Almost all rats injected with superantigen-producing strains developed arthritis. In contrast, only 20% of rats injected with an S. aureus strain lacking superantigen production displayed mild and transient arthritis. Mortality was preferentially induced among the rats inoculated with the S. aureus strains producing SEB and SED. This study emphasizes that superantigen production is an important virulence factor in the development of septic S. aureus arthritis. Differences concerning mortality between staphylococcal strains producing different exotoxins may be dependent on the degree of activation of the immune system.