Evidence has been accumulating for years that gut infections can be treated by introducing beneficial bacteria. A reliable source of healthy bacteria may be healthy people’s feces. Two years ago, Emily Walker explained how and why fecal transfer may cure stubborn and painful Clostridium difficile infections. This week, the New England Journal of Medicine published the best support for the treatment yet: In a randomized, controlled trial, antibiotic treatment cured 31 percent of patients, while fecal transplant cured 94 percent. The original article is below.