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.