I agree with what Bill and the others say above.

Your probiotic should have at least six, if not more, strains including the Bifidus and Salivarus strains as well as Acidophilus et al....

That reminds me, I ran out of probiotics a couple weeks ago and haven't bought more yet, since I haven't been on antibiotics for about five months and my digestion is pretty solid; nonetheless, they contribute to general health and the absorption of key nutrients from your food, so I plan to get more in the next couple of days....