Help me debunk some creationism?

Their example is not correct. Sure, it would be virtually impossible for a find a single bacteria from a population that is resistant to 4 different antibiotics. But, if you considered that it would be a lot easier to take a large population of bacteria and expose them to one of the antibiotics and from that population, you'd get a resistant individual with witch you can make a large population. You would then be able to expose them to the fist antibiotic and a second antibiotic. You'd likely see a population of bacteria which it resistant to both antibiotic arise. And so on. The population would't have to be as great as they say this way. Also, they don't include the notion that many generations occur in the history of a species.