I don't have a source or example and I don't have the time to properly search, but I can provide a quick explanation: The vast majority of resistance mechanism

I don't have a source or example and I don't have the time to properly search, but I can provide a quick explanation: The vast majority of resistance mechanisms are detrimental to the cell that has them. 1. The bacteria consumes energy to be resistant by pumping out the antibiotic, blocking it with a protein or breaking it down with an enzyme. 2. Alters it's billion-years-optimized metabolism or structure to be resistant and this affects it's efficiency. 3. Forgoes on a source of energy because it can't use it anymore. You can read about these mechanisms here: https://en.wikipedia.org/wiki/Antimicrobial_resistance#Mechanisms_and_organisms https://en.wikipedia.org/wiki/Antimicrobial_resistance#Mecha... When in a competition with regular bacteria (no antibiotic around), these resistant cells will be outcompeted and gradually replaced.