I think your concern is a valid one. While Azithromyacin works great and is appropriate for some people, eventually staph infections become resistant to it. The next question is "Is it right for your son?" And an even more important question might be, "Is there any other way to diminish inflammation in the lungs?"
I had my first visit to a CF clinic recently and they strongly touted Azithromyacin to me. They told me they had a patient improve their FEV1 from 29% to 79%. I was impressed...until I read the literature -- that the average improvement was 6% and then there was the resistance problem. And yes, less hospital days.
When I asked my own Pulmonary Doctor about the C.F. Clinic's recommendation, she said, "Why would they recommend that to someone who is stable?" My doctor said, if I was not doing well, she would throw everything at me. But in fact my lung function went up in the last year, doing my own anti-inflamatory protocol. The other problem is that these are short term studies. So for me I decided against it. Maybe for someone else it's the perfect drug.
That still leaves the idea of reducing inflammation, the culprit of many exacerbations and declining lung function. I couldn't possibly list all the things that I do to reduce inflamation, but 11 years ago, after going to this doctor and learning a different way to treat my disease, I got off continuous Tobi, stopped going into the hospital, and my lung function -- instead of going steadily down every year, went up. Amongst the many things I do, I practice strict allergy control. And I'm really not allergic to much. But what is an allergy to one person is an irritant to another.
The obvious: no carpets, using hepa air filters, nasal rinses, pillow protectors, closed windows, avoiding bad air, (there is a lot of info on allergy/irritant avoidance out there)
And the less obvious: stopping a post nasal drip, cleaning only with vinegar and water, hepa vacuum, wearing a mask in cold, smoggy, or windy weather, home remedies so that I don't get colds for more than a day, and since I added hypertonic saline, tumeric and NAC, I haven't been on any antibiotics in 2 years (knock wood).
For me, the more I do, the less symptoms I have. One more note: This is what works for me. Some of these things may not be appropriate for kids.
Hope this helps.
My meds: Foridil, Spiriva, Asmanex, Singulair, Claritin, Astilin, Nasonex, Nasalcrom, Cromolyn Sodium, Xopenex HFA