It is not in the family with pseudomonas, and is not very common.
However, it is enteric (lives in the GI tract) so I'm unsure how you cultured it; and even less sure what to do.
I checked a couple of journals and only found one respiratory related reference. In that one it was indicated in several cases of hospital-acquired pneumonia. But no indication how it was treated, especially since you have CF.
Sorry, but probably need to call the Dr and ask them specifics on their intentions for treating it.