Hospital ‘superbugs’ float in the air

U. LEEDS (UK) — Coughing, sneezing, or simply shaking bed sheets can send superbugs flying, allowing them to contaminate clean surfaces.

The findings by University of Leeds researchers may explain why, despite strict cleaning regimes and hygiene controls, some hospitals still struggle to prevent bacteria moving from patient to patient.

Hospital superbugs, such as MRSA and C. difficile, can be spread through contact. Patients, visitors or even hospital staff can inadvertently touch surfaces contaminated with bacteria and then pass the infection on to others, resulting in a great stress in hospitals on keeping hands and surfaces clean.

But the new results, published in the journal Building and Environment, seem to confirm that superbugs can fly through the air and contaminate surfaces.


PhD student Marco-Felipe King used a biological aerosol chamber, one of a handful in the world, to replicate conditions in one- and two-bedded hospital rooms. He released tiny aerosol droplets containing Staphyloccus aureus, a bacteria related to MRSA, from a heated mannequin simulating the heat emitted by a human body.

He placed open Petri dishes where other patients’ beds, bedside tables, chairs and washbasins might be and then checked where the bacteria landed and grew.

“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,” says Cath Noakes, from the School of Civil Engineering, who supervised the work. “However, we also captured significant quantities of bacteria right across the room, up to 3.5 meters away and especially along the route of the airflows in the room.”

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

The researchers are hoping that computer modeling will help them determine the risk. The findings have been compared to airflow simulations of the mock-up hospital rooms and the research team has 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,” says King.

The Engineering and Physical Sciences Research Council (EPSRC), and the international design and engineering firm Arup, which designs hospitals, sponsored the study.

Source: University of Leeds