I would not assume it was the manager unless this is a pattern with this person. Sounds like everyone might need to talk this out. Is there a trusted person who could help mediate the situation? In the past I have looked for help from other nurses, chaplains, and CNSs who I noticed were pretty good communicators to help me bridge some gaps.
Keep in mind the MRSA being passed around in the hospital is usually different what we are picking up in the community. I'm pretty sure the community is fast becoming full of it. I have two sons who are athletes who have been treated for boils that responded very quickly to bactrim. This was the sign that it was community acquired MRSA without doing a culture. If it had been MRSA that I brought home from the critical care unit I work on I don't think bactrim would have worked. We have decolonized the family with bactriban, hibaclens and bleaching the house.
Wow! I think you are seeing only a very narrow view of nursing. I have been in it for 23 years without regrets. First step is look at your relationships with patients. Nursing is truly a higher calling. It is about providing service to others. It is not about how grateful or thankful the patient is, but how grateful you are to be there for that patient. Once you get that worked out (if you want to be there for patients) then I think you worry about finding the right place to work with manageable ratios. There are places out there.