I have been saying that for a long time to my students including nursing and medical students. This article was publised on the New York Times website
"In 2004, a study from the New York Hospital Medical Center of Queens compared the ties of 40 doctors and medical students with those of 10 security guards. It found that about half the ties worn by medical personnel were a reservoir for germs, compared with just 1 in 10 of the ties taken from the security guards. The doctors’ ties harbored several pathogens, including those that can lead to staph infections or pneumonia.
Another study at a Connecticut hospital sought to gauge the role that clothing plays in the spread of methicillin-resistant Staphylococcus aureus, or MRSA. The study found that if a worker entered a room where the patient had MRSA, the bacteria would end up on the worker’s clothes about 70 percent of the time, even if the person never actually touched the patient."