This decision has to be made individually. Sanitation operations are carried out on medical instruction and must weigh up the risk to the resident and the overall epidemiological situation.
There is no statement from the Robert Koch Institute regarding the frequency of MRSA sanitation in hospitals. If a previously sanitised patient is colonised with MRSA germs again, e.g., because they spent some time at home and is admitted to the hospital, a decision must be made based on the new environment and the expected treatment as to whether sanitisation should take place again. The expected length of stay in the hospital may also play a role. For a short stay, isolation of the patient may be easier to implement; for a longer stay, successful sanitisation may at least lead to the lifting of isolation. Here, the attending physician must decide when and if sanitisation should take place again.