The insensitivity to a particular antibiotic developed by the bacteria against which the antibiotic has been used repeatedly or over a long time. The process works by the ordinary rules of natural selection: that segment of the bacteria population that has a natural ability to counter the drug's effect will survive, so that their genes eventually are shared by the entire population.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.