This is a very interesting point. If you try it, please let us know if this works! It does make sense to me. I have chronic sinus infections also, throughout most of the year, they follow every cold and flu. I didn't use nasal sprays, but as a child my eye doctor had me putting "drops" in my eyes 4 x's a day ( the type that dilate your pupils ). What would these have contained? I could feel them burn all the way down my nasal cavity and then taste them. Yuck! My eyesight is still bad of course. But it would make sense that as a mucous membrane, the sinuses would contain flora. Anyone have any suggestions for us?