Aerosolization of methicillin-resistant Staphylococcus aureus during an epidemic in a Burn Intensive Care Unit

Despite prompt identification of cases, rigorous isolation techniques, negative environmental samples, and largely negative personnel cultures, an epidemic of methicillin-resistant Staphylococcus aureus (MRSA) continued in our Burn Intensive Care Unit (BICU). We sought to determine whether there was any aerosolization of that organism in the unit and if there were air quality characteristics that might have enabled its transmission to patients. We measured air exchange and flow rates into rooms and using a Burkhard air sampler measured MRSA generated inside and just outside the rooms before, during, and after dressing changes in burned patients and in controls. We compared MRSA colonization and disease rates in the BICU before and after renovation. Airflow in rooms was variable with positive pressure rooms found adjacent to negative pressure rooms. In the rooms of patients with burns and MRSA infections, MRSA was found by the air sampling machine at four equidistant parts of the rooms and just outside the door during dressing changes and in one instance before a dressing change. Control patients had negative cultures. After renovation that allowed door closure during dressing changes, increased space per patient and improved indoor air quality, there was a sustained fall in MRSA cases. Dressing changes in MRSA infected burned patients generate infectious aerosols. Knowledge and consideration of that fact greatly influenced renovation of our BICU. Along with other infection control measures, this has led to a decreased number of patients with MRSA colonization and disease.