whoa! I would be HORRIFIED if I were you.
Let's back up a bit and talk about sputum cultures.... they aren't 100% accurate by any sense of the imagination.
When you do a sputum culture, you may only be coughing up phlem from a certain part of your lungs that day. For whatever reason - it doesn't matter why. A week later, you could be coughing up another set of phlem, colonized with different bacteria, than you did a week before..... this is quite common. Now this isn't to say that sputum cultures change DRASTICALLY from one week to another... but they can, and do, vary.
So that's the 1st point where your hospital is INCORRECT...
The second point is that just because you have the same bugs, doesn't mean you have the same suseptabilities. I have pseudo, you have pseudo. My pseudo is resistant to Tobramycin - yours isn't. Or my pseudo is mucoid (it builds a tent around itself to protect itself from antibiotics) and yours doesn't.
I have Staph - you have staph. Your staph is Methacilin resisi (MRSA) and my staph is methacilin suseptable (sorry about my spelling).
So Just because you colonized the same bacteria, that doesn't mean that it's ok for you to hang out with another CFer.
3rdly, bacteria can become resist to antibiotics during an antibiotic treatment.
Let's say you're admitted with pseudo that is suseptable to Tobra. This may be your 20th time on Tobra IV, and finally your pseudo turns resis to Tobra. What if you share a room with a person who is suseptable to Tobra and now they might catch your resis Tobra?
The reasons go on and on and on......
You should be extremely vocal about how wrong this is. Reference the CFF guidelines, and shake your finger at them for being so lax in their infection conrol procedures.
And GOOD FOR YOU for having a gut feeling that this is wrong. You will be a healthier person for it. Applause to you.
And shame on your clinic - it makes me sick that innocent CF patients who don't know any better are being put in positions that could make them sicker. That's just repulsive.