You asked. “Who's denying that?”
So evolution through natural selection of genetic variation explains the development of antibiotic resistance?
Wow! What a useful and predictive theory!
As to variation in bacterial populations - http://en.wikipedia.org/wiki/E._coli_long-term_evolution_experiment
These experimenters took 12 IDENTICAL (in DNA) e. coli and tracked their changes since 1988. Some changes (variations that DID NOT EXIST in the original population) took place in all populations - adapting them to life in the petri dish; and other changes (variations that DID NOT EXIST in the original population) took place in only on population - notably the ability to metabolize citric acid.
So no need to take at face value my assertions that the idiotic idea that all useful variations must already exist somewhere in a population for it to come about has FAILED the test. Just a trifling need to educate yourself in the very basics of a field you have discussed for YEARS without availing yourself of even a basic education on the subject.
*Useful and predictive*? For something common sense and an understanding of variation within species can indicate.
Nobody has to accept species to species macro evolution to understand variation within species.
And understanding that does not by default demand an acceptance of the ToE.
It means that an infinitely creative Creator programmed it into life when He created it.