May 18, 2011 at 7:32 PM ET
There's good news for germaphobes this graduation season: As you shake hands with a school official when receiving your diploma, you can do so with little fear of picking up any harmful bacteria in the process, suggests new research.
In this first-of-its-kind study, researchers looked at 14 elementary or high school principals and college deans in Maryland who would be giving out diplomas. Before the ceremony, both the left and right hands of participants were cultured for bacteria after they cleaned them with hand sanitizer.
Although school officials used only their right hand to grip a graduate's hands, both hands were again cultured for germs after graduation. The results appear in the June issue of the Journal of School Nursing.
In more than 5,200 handshakes given out during these May graduations, researchers found that only one school official had a disease-causing bacteria, methicillin-sensitive Staphylococcus aureus (MSSA) on the right hand before the ceremony. After the graduation, MSSA was found on a left hand and methicillin-resistant Staphylococcus aureus (MRSA) was discovered on a right hand.
MRSA is a type of staph bacteria that can infect skin and other parts of the body and is resistant to some antibiotics.
"I was surprised to find anything growing on hands a minute after school officials used hand sanitizer," says lead author Dr. David Bishai, a professor in the department of population, family, and reproductive health at the Johns Hopkins Bloomberg School of Public Health in Baltimore. "But 93% of the time, I could find bacteria growing on a hand that was just sanitized." He suspects that products designed to kill 99% of germs still leave thousands more remaining on the skin.
Based on their findings, the researchers estimate the chance of hand contamination at graduation is 1 in 5,209 handshakes. This rate is 100 times lower than a health worker's odds of contamination with MRSA when caring for hospitalized patients.
Bishai says seeing staph bacteria on hands, even the methicillin-resistant strain was expected, since it's present in the nostrils and in cuts and scrapes that are healing. Yet researchers hadn't anticipated seeing so few disease-causing bacteria overall and were also surprised they found no fecal bacteria, the kind seen when hands aren't washed after going to the bathroom.
As for why the left hand of one school official had staph bacteria even though it did not shake any graduate's hands, researchers suspect the hand likely picked it up by touching lecterns, diplomas and furniture during the event.
What's Bishai advice to this year's crop of graduates and educators as well as politicians and clergy, whose job often finds them extending a hand?
"Shaking hands is probably not as dangerous as you think," he points out. While the risk of exposure to disease-causing germs is not huge, it makes sense to "keep your hands clean, but don't get neurotic about shaking hands."
In other words, get out there and grip-and-grin for the camera and enjoy the celebration.