As said by Philpy,
It's a matter of Macroevolution vs. Microevolution. Bacteria DNA can mutate and by the process of natural selection, adapt to be antibiotic resistant. This does not contradict what the Bible teaches and says nothing on the order of "The Origin of Life". You would have to make some pretty outlandish assumptions to come to a conclusion that answers such a question. Too often scientist think that science can answer all of life's big questions and fall into the trap of scientism. Nothing about my chemical, cellular, genetic, physiological, or anatomical makeup tells me where life came from and why life on Earth exists. For that you must lean on what people have said in the past, their credibility, their reliability, and their validity. No one else in HISTORY has gotten in right and who has proved who he claimed to be other than JESUS CHRIST.
Source:
Current undergraduate studying for BS Biological Sciences ('15)