My daughter has treated for numerous staph infections, including one MRSA (Methicillin-resistant S. aureus) infection.
Our experience has been, she sees an increase in sputum, culture shows staph, she takes oral antibiotics for two weeks, she is back to normal with very little sputum and cough.
With many CFers once you get MRSA, you have a hard time completely eradicating it. Our nurse said my daughter was an exception to what they typically see, because she was able to get rid of the MRSA. The first and last time she cultured MRSA was about 5 years ago or more. Also, she hasn't had any infections in almost 2 years now.
I'm sorry I cannot remember what antibiotics we used to treat the MRSA, but I do know it was two different kind and they were both oral.
Generally speaking a staph infection for her means she has increased, ugly color sputum to cough up, and she feels more run down (makes sense... her body is busy fighting off an infection) but other than that she usually makes it through her normal daily stuff, she just doesn't do anything extra until she kicks it.
She has always treated with oral antibiotics for 14 days, but usually starts to feel better by day 3 or so.