A chemical germicide is pinned down two ways. First by the surface it is safe on, living tissue (an antiseptic) or a non-living object (a disinfectant). Second by its level, meaning how far up the ladder of microbial resistance it can kill. Pick an agent, set its strength and contact time, then add blood to the surface and watch the reach fall.
Coccidia such as Cryptosporidium sit just under the endospores on this ladder. Everything above a line is harder to kill than everything below it.