Clumping factor A

{{Short description|Protein}}Clumping factor A, or ClfA, is a virulence factor from Staphylococcus aureus (S. aureus) that binds to fibrinogen.

ClfA also has been shown to bind to complement regulator I protein.{{cite journal |title=Staphylococcus aureus clumping factor A binds to complement regulator factor I and increases factor I cleavage of C3b |journal=The Journal of Infectious Diseases |volume=198 |issue=1 |pages=125–33 |date=July 2008 |pmid=18544012 |doi=10.1086/588825 |author1=Hair PS |author2=Ward MD |author3=Semmes OJ |author4=Foster TJ |author5=Cunnion KM |doi-access=free }}

It is responsible for the clumping of blood plasma observed when adding S. aureus to human plasma. Clumping factor can be detected by the slide test.