Are people visiting an MRSA-colonised patient allowed entry to the room without prior hygiene measures?

No.
Background:

The Robert Koch Institute (RKI) stipulates that visitors are required to take the necessary protective measures to prevent the further spread of MRSA in hospitals and other medical facilities. These measures, which include wearing mouth -nose protection, a protective gown, and hygienic disinfection of the hands, should be explained to the visitors. Visitors should also disinfect their hands before leaving the room.

References:
KRINKO (2014) Empfehlung zur Prävention und Kontrolle von Methicillin-resistenten Staphylococcus aureus-Stämmen (MRSA) in medizinischen und pflegerischen Einrichtungen. Bundesgesundheitsbl 57:696-732.