To test what type of greeting might spread the most germs from one hand to another, one researcher would dip a gloved hand into a container brimming with a fairly harmless strain of E. coli bacteria. That researcher would then shake, fist bump or high-five the gloved, but clean, hand of another researcher. The glove that had been germ-free to start with was then tested for levels of E. coli bacteria.
The handshake turned out to be the dirtiest exchange of all, spreading twice as many germs as a high-five and about 10 times as many germs as a fist bump, the investigators found.
Using paint in a second round of tests, the researchers found that more of each person's hand touched the other person's hand in a handshake, and that they tended to last longer. They theorized that those two facts might explain why handshakes are the least sanitary exchange.
This latest finding broadens the recent call from the Journal of the American Medical Association to ban handshakes in hospitals, according to the news release.
Health care providers can spread harmful germs to patients through hand contact, and lead to health care-associated infections, which are one of the leading causes of preventable harm and death in the United States, the news release said.
One in 25 hospitalized patients develops such an infection, and 75,000 patients with these infections die during their hospitalization each year, according to estimates from the U.S. Centers for Disease Control and Prevention.
Visit the U.S. Centers for Disease Control and Prevention for more on hand hygiene.
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