Answer:
Yes, drug resistance existed before, but it increased after the widespread use of antibiotics
Step-by-step explanation:
Drug resistances in bacteria usually occurs as a consequence of mutation. Individuals that carry the resistance mutation survive even after the treatment with antibiotics. So, these mutations are advantageous for bacteria and thus, become favourable by natural selection (natural selection is evolutionary mechanism which favours traits of an organism that help him survive and reproduce). Resistant bacteria that survived after the use of antibiotics had the favuoruable trait (resistance) by natural selection.
Bacteria can even transfer drug-resistance to other bacteria via the process of conjugation, transducton or transformation.