Easiest explanation is "that which does not kill you, makes you stronger". That rule definitely applies to bacteria. When providers prescribe antibiotics, patients typically do not finish the dosage;...
Genetic mutations in the bacteria can cause them to become resistant to particular kinds of medication. As the reproduction rate of bacteria is so high, even just one bacteria with the gene that...
I'm going to take a wild guess here that you mean: "Can you build up a tolerance to Digitalis to the point where it does not work anymore?" As far as I know, the answer is "no".