Learning from Nature: How Bacteria Become Resistant to Antibiotics

1. The bacteria may acquire an enzyme that that can either act like a pair of scissors, cutting the antibiotic into an inactive form or modify the drug's chemical structure so that it is no longer effective.
2. Pumps inside the antibiotic can spit out the drug once it penetrates the cell wall. This was discovered 30 years ago by Dr. Stuart Levy at Tufts University School of Medicine and greeted with profound skepticism at the time.
3. The bacteria may mutate its inner contents so that the drug can no longer inactivate its target.

Source: Superbugs, by Jerome Groopman, The New Yorker, August 11 & 18, 2008