The bacteria remain bacteria; there is no evolution. While less resistant strains are eliminated by the medicine, the resistant strains that are already present multiply. So all that is going on is a change in constitution due to the antibiotic.
http://creation.com/superbugs-not-super-after-all
Mutations, not even once?
"If in a population of 1000 bacteria you have one individual who possesses a mutation for antibiotic resistance, and you don't take antibiotics, then there's no advantage to that mutation. The mutation won't be selected for, so it won't become more common. Furthermore, muller's ratchet tells us that genes are deleted in asexual populations, because genes have a cost to produce and maintain, so losing the weight of neutral genes is actually advantageous. Antibiotic resistance could be selected against if antibiotics are absent from the environment."