It's a common phenomenon. When Hospitals employed their own cleaners, who kept mainly to 1 Ward to avoid cross-infection, there were few outbreaks, in 8 years I never heard of any. Then the cleaners were out-sourced which often means that they flit from Ward to Ward as well as who knows where they are prior and after cleaning in the hospital!
The Nurses were charged with cleaning beds down between each patient, that is stripping laundry, washing down the WHOLE bed frames, washing and turning mattresses, under the beds and walls, bed-side cabinets were washed inside and out …….