probiotics

My vet thinks my cat has a nasal polyp that has been continuously collecting bacteria and giving her URIs that are treated with antibiotics and then return. While we are working with our vet to get it taken care of I would like to put my cat on some sort of probiotics that might help boost her immune system in hopes she will not get another infection while we are sorting out everything out and hopefully removing the polyp. I've seen probiotics to help with digestive problems, but has anyone put their cat on probiotics to boost their cat's immune system for URIs? What kind of probiotics would I use?

L-lysine might be more appropriate especially if the URI is feline herpes.
L-lysine boosts the immune system in general; as I understand it, probiotics are more helpful for digestive issues. Please someone correct me if I'm wrong: I give Ritz probiotics mainly for her digestive issues and would love if it also boosted her immune system.
Here is a thread about l-lysine, among many others threads.

Any time a cat has been on antibiotics, it's a good idea to use probiotics to restore the normal good bacteria. I don't think it will directly help prevent URIs, but it does help with overall health which can make them more resistant to infections generally.

Just a note: probiotics should be given at least two hours before or after antibiotics or the probiotics will counteract the antibiotics.

Thanks Ritz, I had her on l-lysine before, because I thought it might have been herpes, but my vet said that it was not and that l-lysine would not be helpful (though not hurtful either). I didn't get a chance to ask about the probiotics because my husband picked up her meds last time, but thanks for the tip about taking 2 hours before/after antibiotics.

Momto3cats what kind of probiotics do you use when your cats are on antibiotics? thanks