Why should we not overprescribe and overuse antibiotics?

Antibiotics are used for killing bacteria and therefore, it can act as a selection pressure. This means that the bacteria can mutate, in order to avoid being killed and this would be a favourable mutation, as only those bacteria that have this mutation will survive to reproduce. This selects out those bacteria with the mutation (and kills off all the ones without the mutation) and therefore: the antibiotic wil no longer work. Overuse of antibiotics exposes the bacteria already present in our body to the selection pressure and could potentially cause mutations to come about.