Germ Theory (Microbe) ---> Terrain Theory (Bloodstream Medium) ---> Alter Terrain Inhibit / Eliminate Microbe?
"germ theory, in medicine, the theory that certain diseases are caused by the invasion of the body by microorganisms, organisms too small to be seen except through a microscope."
https://www.britannica.com/science/germ-theory
"Most often, the bloodstream is the vehicle for carrying medicines throughout the body"
https://www.livescience.com/45241-medicine-journey-through-body-nigms.html