My first picc line was because oral antibiotics just weren't taking care of the problem at that point. However, for a while I was still sometimes able to use them. We would try oral antibiotics first. If they didn't work, I would do IVs with a picc line. Actually, cipro or levaquin still worked for me at times, but I had to quit taking them because they were causing me too many issues. That left me no oral choices for PA, so now I do IVs any time it needs to be treated. However, I still usually take oral Zyvox for MRSA.
A couple of years ago I got a port, and that makes IVs much easier.