It can be harmful in certain situations (weak, frail elderly patients with open wounds). To most adults there is minimal risk, the treatment for Mrsa is a cream you apply twice a day up your nose called naseptin and a medicated antibacterial body wash called chlorhexidine. In some cases you may need antibiotics. Once you've contracted the infection you carry the toxins from the Bacteria in your system for the rest of your life, so once you go back into a hospital environment the bacteria may become active again.
In our hospital we advise not to bring young babies to visit their family members that have hospital infections (C-Diff mainly!), however you take it at you own risk, and use common sense...
Wash yours and your children's hands with soap and water when leaving!
(The alcohol gels provided do not kill all bacteria).
If it was that dangerous they would make us nurses and health care assistants have constant treatment and bleach us down after every shift hehe!
Hope your mum makes a speedy healthy recovery x x x