Public sanitation and antibiotic drugs have brought about historic increases in the human life span; they have also unintentionally produced new health crises by disrupting the intimate, age-old balance between humans and the microorganisms that inhabit our bodies and our environment. As a result, antibiotic resistance now ranks among the gravest medical problems of modern times. Good Germs, Bad Germs addresses not only this issue but also what has become known as the "hygiene hypothesis"— an argument that links the over-sanitation of modern life to now-epidemic increases in immune and other disorders. In telling the story of what went terribly wrong in our war on germs, Jessica Snyder Sachs explores our emerging understanding of the symbiotic relationship between the human body and its resident microbes—which outnumber its human cells by a factor of nine to one! The book also offers a hopeful look into a future in which antibiotics will be designed and used more wisely, and beyond that, to a day when we may replace antibacterial drugs and cleansers with bacterial ones—each custom-designed for maximum health benefits.