Oh, I think this study is actually very helpful! GSH itself has antibiotic activity against PA--this is something that I have felt for a long time based on the research I have done, but there was no empirical evidence for it. Now there is.

As for the issue of antibiotics, more knowledge can only be good. Some folks on the list stop GSH when on antibiotics, and some do not. People didn't have much to go on while making this decision. Now we have the beginning of a research thread that will clarify for which antibiotics each course of action might make more sense. But there is a background context that must be kept in mind: if you will recall Dr. Visca's observational study--which is in vivo and not in vitro--overall, CF pts were better able to fight PA while on GSH than while not, and a few no longer cultured it after several months. So I think there is more to learn than this one article gives us, and "in vivo" studies, as you say, may give us a more holistic picture than in vitro studies. So I rejoice in new knowledge as it comes out! Let there be many more studies on this question, and especially, let there be more in vivo studies. The more we learn, the better!

But yes, as you say, another thing that must be kept in mind is that normal people have many more times the amount of GSH in their extracellular milieu than CF people--and normal people clear bacteria much more readily without hurting their epithelial cell layer in the process . . . .