Here's a link I found that helps to explain the bacterial infections in CF patients, including pseudomonas - http://www.hopkinscf.org/main/whatiscf/science_lungbac.tml. If you read the page, you can click on the tabs on the top of the picture to see CF infections described visually.
If at the end of this round of antibiotics he is still growing pseudomonas, we will likely get put on IV antibiotics. I expressed my desire to do that from home vs. being put in the hospital. Its every 8 hours for 2 week and would need a PICC line put in (sort of like a port), but at least we could manage it from home. The purpose of this would again be to try to eradicate. You can compare pseudomonas to something like smoking, as far as what it does to your lungs and how quickly. Its a nasty and resistant bacteria that over time causes decreased lung function and ultimately lung disease, so we need it gone today. You smoke a cigarette today, not much is going to happen to you. But smoke one tomorrow too, and the next day, and so on and so forth and your lungs can take off their sunglasses because their future ain't so bright :)
Please hope and pray that we can get rid of it with the Tobi & Cipro. And just as a little FYI, the CF Foundation, who you so kindly donate to by supporting team Doin' It For Drew, is responsible for all of the research and science that went into creating Tobi, the first new oral antibiotic created to treat pseudomonas in over a decade. Just sayin' :)