WASHINGTON — U.S. health officials on Wednesday approved the first pill made from healthy bacteria found in human waste to fight dangerous gut infections — an easier way of performing so-called fecal transplants.

The new treatment from Seres Therapeutics provides a simpler, rigorously tested version of stool-based procedures that some medical specialists have used for more than a decade to help patients.

The Food and Drug Administration cleared the capsules for adults 18 and older who face risks from repeat infections with Clostridium difficile, a bacteria that can cause severe nausea, cramping and diarrhea.

C. diff is particularly dangerous when it reoccurs, leading to between 15,000 and 30,000 deaths per year. It can be killed with antibiotics but they also destroy good bacteria that live in the gut, leaving it more susceptible to future infections.