Is methicillin-resistant Staphylococcus aureus aerosolised when healthcare workers carry out activities for patients?

Abstract

The aim of this study was to determine how often methicillin-resistant Staphylococcus aureus (MRSA) is found in aerosols while healthcare workers were undertaking routine care of patients (e.g. taking blood pressure, making beds). Air sampling was conducted using an air sampler and environmental settle samples in single rooms of patients who were either colonised or infected with MRSA, using a Merck MAS-100 air sampler and MRSA chromogenic agar. The air samples and environmental settle samples were collected between 0700 and 1530 hours over a 10-day period. A total of 99 air samples and 26 environmental settle samples were collected: 29/99 (29%) of the air samples and 5/26 (19%) of the environmental settle samples were positive for MRSA. Of the 10 rooms sampled, eight (80%) had MRSA present in air samples. Concentrations ranged from 1 to 128 colony-forming units m⁻³. Thus, MRSA can frequently be aerosolised. Although the overall contribution of aerosolisation in the transmission of MRSA is unclear, these findings add further evidence to justify the use of gloves and gowns for staff having contact with MRSA-positive patients or going into the rooms, as environmental contamination is likely to be frequent. Masks should be used more often, especially whenever activities likely to generate aerosols occur, such as bed-making, sputum suction or chest physiotherapy.