MRSA is only dangerous if it get’s into an open wound. It lives in many people outside hospitals un-affecting their host in warm; moist areas; e. g. nose, crotch.
Unfortunately I had a small burn on my leg that became infected. Went in hospital; contracted MRSA and had my leg amputated as a result.
There is one antibiotic that can treat this infection that the doctors hold back. I’m sure they will be able to treat your niece. Mine happened some 10 years ago and because of it I will not even visit anyone in hospital.
So yes she can pick it up outside hospital and I cannot stress how important it is to be scrupulously clean.
My dad always said to me “you must eat a peck of dirt before you die” but in today’s day and age you cannot be a child dirt searcher like I was.
All the love in the world to her; don’t worry they know more about treating this infection today than in my day.