CAMP factor is a diffusible, heat-stable protein produced by group B streptococci. This is a synergistic test between Staphylococcus aureus and Streptococcus agalactiae . S. agalactiae produces CAMP factor. S. aureus produces sphingomyelin C, which binds to red blood cell membranes. The two bacteria are streaked at 90 o angles of one another. They do NOT touch. The CAMP factor produced by S. agalactiae enhances the beta-hemolysis of S. aureus by binding to already damaged red blood cells. As a result, an arrow of beta-hemolysis is produced between the two streaks. The test is presumptive for S. agalactiae that produces CAMP factor.