Gut flora suppositories are a thing, and have been since before WW2.

Seems there was a guy in WW2 with golden guts, who survived the trenches and bad food, dysentery and such unscathed. Doctors then took samples of his gut biome and started using them to treat others who were less fortunate. Like Hitler with his life long chronic flatulence problems.

These days you can take a simple pill that's designed to open up once it reaches the large intestine the long way, rather than the shortcut. It's sold under the brand name Mutaflor, but it's the same stuff, just freeze dried and encapsulated for oral consumption.