Antibiotics are marvels of modern medicine but overuse has created deadly strains of bacteria that can’t be treated. Where and how could prescriptions be curtailed to have the biggest effects? Dr. David Wallinga, a senior health official at the National Resources Defense Council, talks with Dr. Josh Sharfstein about the murky picture of unnecessary antibiotic use in animals in the US and the “dismal” near future where many more may die before efforts are made to get overuse under control.