Be Careful With the Powerful Medicine That Is Poop

It has recently become clear that each one of us is more microbe than human—at least when it comes to the number of cells in our bodies. The bacteria that swarm through our guts, across our skin, and in every orifice you have outnumber our human cells by at least 10 to 1, though their much-smaller size keeps that from being too obvious.

Having the right balance of these bacteria is infections: when these bacteria get established in people’s guts, they can disrupt the balance of other microbes and . Antibiotics are not as effective against as they used to be, and little by little, doctors have been giving patients in danger of losing their lives transplants of bacteria from healthy people’s guts. These treatments, called fecal transplants, involve collecting samples from donors, testing it to guard against giving patients other diseases, and administering it to the patient, during a colonoscopy or by other methods.