Sunflower,
Due to overuse of IV abx over the past 2 years, I quickly became resistant to every single one except zosyn (to which I'm allergic!)
They send my culture out to get it synergy tested now. It takes a really long time to get the results back though, so I'd suggest you have them do it right away. That will give you 2-3 combos of meds that will knock down the bug you're growing at that time. We're currently awaiting my syngery testing to see what they can treat my 2 strains of pseudo with. I'm excited, because before, when they'd just blindly throw 2 abx. at it that I was "intermediately" sensitive to, I never got feeling very well, so I'm hopeful getting the exact combos that should work will prove successful.
I've also heard that just cause you're resistant to Tobramyciln IV, you can still get benefit from TOBI inhaled. So, I'd maybe still try it or use it. One of my pseudo bugs is resistant to coli, but I still inhale it every other month.
Another thing is that my docs have always said a sputum culture is often only half the story. We often grow different things if you look down deep in the lungs, so it is possible that doing TOBI may help with other bacteria in your lungs that you may not be aware of. Just a thought.
Best of luck. I know its very frustrating to be resistant to everything. Especially when you haven't been on IV meds much! Urgh.