As an evolving culture we seem to be emerging from the FDA trial and error methods (and if that doesn't work, try a bigger sample). My guess is that Fleming started out w/one petri dish. He was bright enough to note that what he saw should not be happening, but it did. As I understand it that is about what Dr.M. said/thought when he noted the Homeostasis hypothesis w/restore and regen as an explanation for the 32 patient safety trial. "That" is not supposed to happen.
As you have continuously pointed out here, shat happens.