I honestly didn't know until reading your thread that there was a question of interference. That said, there are some oral antibiotics that I simply cannot tolerate or tolerate for very long unless I take a probiotic at the same time. So, unless I was dealing with a resistant strain of something and had been on more than one round of antibiotic, I think I might be willing to just take that risk.
While I was in law school, I went through a period where I was in a ton of GI distress. I was bloated and gassy like nobody's business. It was awful. At the time, I thought that maybe I'd developed a lactose intolerance. I cut out dairy and eventually felt better. In retrospect, I tend to think that a round of antibiotics I took during an UR infection was the culprit. That didn't dawn on me until years later when I experienced similar distress after being treated for a sinus infection. I'm now pretty religious about taking probiotics while using most antibiotics.
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher