seattle, only for his doctors to discover a microscopic organism that could kill him. >> ricci: my doctor said, "david to tell you something really hard. you have an infection we've never seen before." >> williams: doctors in the u.s. hadn't seen much of this? >> ricci: they'd never seen it, they didn't, they didn't even know how to treat it. >> williams: the infection growing inside ricci's leg was caused by bacteria with genetic mutations that turned them into superbugs, resistant to 19 different antibiotics. his doctor told us that in desperation, he had to reach back in time, to an antibiotic called colistin that was discovered in the 1940s. for decades, it was rarely used, because in high doses, it can cause irreversible organ damage. ricci suffered kidney failure three times. what did it do to you? >> ricci: it felt like my organs were disintegrating. it just felt really, really strange, something i'd never felt before, like i was dying from the inside out. >> williams: but after six months, the colistin helped beat back ricci's infection, and he learned to walk again. we went to the neighborhoo