I have cultured PA for the "first time" twice - the actual first time my doctor put me on tobi for three months straight, and Cipro for a long time, although now I can't remember the dose or for how long it was - I know it was at least a month and I got C. diff - I would definitely recommend taking a good probiotic while on Cipro!
After several years of culturing PA, it stopped showing up in my cultures. That lasted for about 3 years. I started culturing it again in April, this time with a different doctor. It showed up as an exacerbation - my FEV1 was down 20% - so my doctor put me on two weeks of IV Tobra and Ceftaz. After that, I started doing Cayston every other month. I had two PA free cultures, but it showed up again in my last one. I felt fine, but my doctor still put me on two weeks of Cipro. I believe it was 500mg twice a day.