October 11, 2012
Superbugs Spread, Fly Through The Air In Hospitals
Brett Smith for redOrbit.com — Your Universe Online
Despite the best efforts of hospitals to maintain effective sanitation levels, dangerous ℠superbugs´ can drift along air currents and spread from patient to patient, according to new research from the University of Leeds in the U.K.
Previous studies have shown superbugs, like the difficult-to-treat MRSA, have spread around hospital wards through contact. These pathogens can be passed to surfaces, picked up by individuals, and enter the body through scrapes and cuts.
The new study, published in the latest edition of Building and Engineering, demonstrates that the most vigilant hospital cleaning may not be enough to prevent superbugs from spreading. Sneezing, coughing, or shaking bed sheets were all shown to move the superbugs around a specially designed biological aerosol chamber.
The Leeds team, led by PhD student Marco-Felipe King, released aerosol droplets with Staphyloccus aureus, a bacteria related to MRSA, from a heated mannequin designed to simulate a human body. They placed open Petri dishes on surfaces around the experiment chamber and later checked where the bacteria landed and grew into colonies.
Three different scenarios were tested during the course of the experiment: an empty chamber, a single-patient room and a double-patient room.
The results of all three scenarios demonstrated the mobility of pathogen-containing aerosols that were “deposited throughout a room with no clear correlation between relative surface concentration and distance from the source,” the report 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,” co-author Cath Noakes, from the University´s School of Civil Engineering, said in a statement. “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.”
The study also refuted the commonly held notion that aerosols smaller than 5 micrometers are taken up by hospital ventilation systems and not deposited on surfaces. These tiny aerosols were deposited on surfaces in the experiments and suggested that superbugs can be transmitted through indirect contact.
The researchers also noted physical partitions could be used effectively to reduce the transmission of contaminants. This information, along with the rest of the team´s findings, will be used to generate computer models that will inform the future design of hospital rooms, particularly how ventilation systems are utilized.
“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 King.
The study was sponsored, in part, by the hospital design firm Arup.
“We are looking at healthcare facilities of the future and it is important that we look at key issues such as infection control,” said Phil Nedin, director and global healthcare business leader at Arup. “Being involved in microbiological studies that inform airflow modeling in potentially infectious environments allows us to get a clear understanding of the risks in these particular environments.”