Frederick Sanger

I would call this  natural elcoogical selection .  I copied the following excerpt from Wikopedia, and can be applied to your scenario too: A well-known example of natural selection in action is the development of antibiotic resistance in microorganisms. Antibiotics have been used to fight bacterial diseases since the discovery of penicillin in 1928 by Alexander Fleming. However, the widespread use and especially misuse of antibiotics has led to increased microbial resistance against antibiotics, to the point that the methicillin-resistant Staphylococcus aureus (MRSA) has been described as a  superbug' because of the threat it poses to health and its relative invulnerability to existing drugs. It was thinking about your question.  Pass on the good Karma!