It's a probability game isn't it. There's a chance of that super super bug given normal antibiotics. But also chances are that any super super bug is going to have a downside that stops it spreading unhindered through other hosts or something like that.

There's always the possibility of a microbe/prion/other that can attack and consume all DNA based life forms. Or a 'nearby' gamma ray burst that sterilises everything within 200 light years.