Infection control and prevention in five acute hospitals is being affected by overcrowding.
A new report from Hiqa shows the issue is also being impacted by old and unsuitable infrastructure.
Five hospital inspections were carried out between April and June.
Of the five, maintenance and infrastructural deficits in three hospitals had not been addressed since the last inspection.
Those hospitals were Croom in Limerick, Nenagh Hospital and Sligo University Hospital.
It says Croom and Nenagh also had no one designated as the lead or coordinator for decontamination.
However Hiqa does say all five hospitals have leadership, governance and management arrangements for infection prevention and controls were in place.