The problem with probiotic supplements is that they have a handful of strains of bacteria in them, where as your intestines have many, many more and in different locations. Additionally, the science is till out if probiotic supplements even get to where they are supposed to be going. But then, if you cram a pill up your butt that is one way to deliver the goods.
And yes, the sugars in my latte enema would feed those gut flora in a bad, bad way. Straight up coffee is the way to go.