I agree that both doctors and dentists have been too ready to prescribe antibiotics, sometimes in cases of mild infections which would have resolved anyway, and some, especially with dentists, as emergency treatment instead of properly opening and draining an abscess for example..
Apparently some antibiotics are becoming ineffective and this leads to combinations being prescribed but ultimately even these could become less than effective.
Unfortunately it seems that really new antibiotics are not easy to find or cost effective to develop so this is a problem that really needs addressing as you so rightly say.