Yes, it keeps your gut flora healthy while your antibiotics do their thing.
Dad always liked an occasional glass of buttermilk, and I thought it was gross. Now I get it-- love this stuff.
I'm ready for stopped-up ear and ear ringing to go away. 4 days of horse pills and still I have that. Meh.
I was careful thereafter to drink from the unmolested side of the buttermilk. I love the streaks on the glass as it dries.