I know it is heartbreaking when something 'new' occurs. My younger daughter, Hannah, cultured PA for the first time about two years ago. When the CF nurse called me, all I could say was "That sucks!" And of course I was concerned that my older duaghter, Kayla, would also start culturing it (She has lung damage already due to MRSA and I just didn't want to add more to the mix...).
But, we were in the EPIC study and the course of the study that she fell into was to start inhaled Tobi and Cipro (or placebo of Cipro...not completely sure if she got the real deal). She did two rounds of Tobi and Cipro/placebo, and had about a year of clear cultures. Then a year later we did one more round after culturing PA again. That was a little over a year ago, and she has had all clear cultures of PA. I do think she was on the placebo b/c the last time she was sick and culturing PA, she wasn't getting better after almost two weeks of Tobi and Cipro/placebo. Her CF doc had us stop the Cipro/placebo and put her on what we knew was Cipro, and she got better within a few days.
By the way, Kayla never has cultured the PA, which completely shocked me.
Don't beat yourself up over all of this. You sound like a great Mommy<img src="i/expressions/face-icon-small-smile.gif" border="0">