Superbugs go airborne to infect more patients

The results of the study at Leeds University may explain why some hospitals still struggle to prevent bacteria moving from patient to patient despite strict cleaning regimes and hygiene controls.

Patients, visitors and hospital staff can pass on infections including superbugs MRSA and Clostridium difficile by inadvertently touching surfaces contaminated with bacteria.

But the research in Leeds reveals details of how coughing, sneezing or simply shaking the bedclothes can make superbugs airborne, allowing them to contaminate recently-cleaned surfaces.

Researcher Marco-Felipe King used biological aerosol chamber, one of only a handful in the world, to replicate conditions in one and two-bedded hospital rooms. He released tiny aerosol droplets containing a bacteria related to MRSA from a heated dummy which simulated the heat emitted by a human body and checked where the bacteria landed and grew.

Cath Noakes, of the university’s School of Civil Engineering, said: “The level of contamination immediately around the patient’s bed was high but you would expect that. Hospitals keep beds clean and disinfect the tables and surfaces next to beds.

“However, we also captured significant quantities of bacteria right across the room, up to 3.5 metres away and especially along the route of the airflows in the room.”

Co-supervisor Andy Sleigh said: “We now need to find out whether this airborne dispersion is an important route of spreading infection.”

Researchers are hoping that computer modelling will help them determine the risks from superbugs. Their findings have been compared to simulations of airflows in the mock-up hospital rooms and the research team have shown that they are able to accurately predict how airborne particles can be deposited on surfaces.

“Using our understanding of airflow dynamics, we can now use these models to investigate how different ward layouts and different positions of windows, doors and air vents could help prevent microorganisms being deposited on accessible surfaces,” said Mr King.

The international engineering firm Arup, which designs hospitals, part sponsored the study.

Phil Nedin, global healthcare business leader at Arup, said: “We are looking at healthcare facilities of the future and it is important that we look at key issues such as infection control. Being involved in microbiological studies that inform airflow modelling in potentially infectious environments allows us to get a clear understanding of the risks in these particular environments.”

The research, part funded by the Engineering and Physical Sciences Research Council, is published in the journal Building and Environment.