In 2010, Americans were prescribed 258 million courses of antibiotics, a rate of 833 per thousand people. Such massive usage, billions of doses, has been going on year after year.
We have few clues about the consequences of our cumulative exposures. We do know that widespread antibiotic treatments make us more susceptible to invaders by selecting for resistant bacteria.
These risks are now well-known, but I want to lay out a new concern: that antibiotic use over the years has been depleting the pool of our friendly bacteria -- in each of us -- and this is lowering our resistance to infections. In today's hyperconnected globe, that means that we are at high risk of future plagues that could spread without natural boundaries from person to person and that we could not stop. I call this "antibiotic winter."