Fibronectin-binding proteins and fibrinogen-binding clumping factors play distinct roles in staphylococcal arthritis and systemic inflammation.

Staphylococcus aureus is a commonly encountered pathogen in humans, and it has the potential to cause destructive and life-threatening conditions, including septic arthritis. The pathogenicity of staphylococci depends on the expression of virulence factors. Among these, staphylococcal cell-surface proteins with tissue-adhesive functions have been suggested to mediate the colonization of host tissues, a crucial step in the establishment of infection. We investigated the relative contribution of the fibronectin-binding proteins (FnBPs) and fibrinogen-binding clumping factors (Clfs) to staphylococcal virulence in an experimental model of septic arthritis. The results show that these 2 sets of proteins play distinctly different roles in the development and progression of septic arthritis. Although Clfs significantly contributed to the arthritogenicity of S. aureus, FnBPs had no effect on the development of arthritis. Conversely, FnBPs played an important role in the induction of systemic inflammation, characterized by interleukin-6 secretion, severe weight loss, and mortality.