Piper started culturing mrsa when she was around 7, and her lung health has significantly declined since then. It has been a gradual decline, IVs a couple times a year, then three or four, and now (she's 10) we're doing IVs roughly every six weeks. It is the only thing she has cultured repeatedly, so nowhere else to put the blame. That said, there are different strains of staph, and I've never heard of any studies that looked at particular strains. It could very well be that the particular strain she has is one of the worst. Her lung function right now is in the 50's on a good day. We've also been fairly aggressive with it from the time it started causing problems. She's done daily bactrim (didn't seem to make a huge difference) and still does daily ibuprofen therapy, and azithro 3x weekly. She also rotates Cayston, TOBI, and Colistin. She cultured pseudo until she was 3, so there's also some thought that maybe she's still culturing pseudo and we're not seeing it on the cultures because of the mrsa. There are times it feels like we're throwing darts at an invisible dartboard, but I also hate to think what her lung function might be without all the various protocols we follow. Honestly, it bites, and I think there's been a big misconception here that staph isn't a big deal, though recent studies are starting to change people's minds.