80 million bacteria are swapped with each French kiss

When little kids think about French kissing, they are likely to express an emphatic “Ew!” Their response isn’t unfounded. Who knew so much bacteria exchange was going on during a time of romance? Research from Remco Kort of TNO Microbiology and Systems Biology recently published in Microbiome illustrates how not only is bacteria shared during […]

When little kids think about French kissing, they are likely to express an emphatic “Ew!” Their response isn’t unfounded. Who knew so much bacteria exchange was going on during a time of romance?

Research from Remco Kort of TNO Microbiology and Systems Biology recently published in Microbiome illustrates how not only is bacteria shared during a make out session, but the more often you kiss, the more likely the bacteria in your mouths will be the same.

In order to get some raw data, Kort and colleagues recruited 21 couples visiting the Artis Royal Zoo in Amsterdam. They asked the couples to fill out questionnaires individully about how they kiss, how often, when they last kissed, and what they last ate. After that, a tongue swabs were taken to check out the oral microbiota in each person’s saliva.

“We wanted to find out the extent to which partners share their oral microbiota,” Kort explains in a news release, “and it turns out, the more a couple kisses, the more similar they are.”

To make the data a little bit more controlled, researchers then gave one person a probiotic drink and then had them kiss his or her partner.

The quantity of probiotic bacteria in the receiver’s saliva rose threefold. In order to calculate the number of bacteria passed on in a kiss, the team had to rely on average transfer values and assumptions related to bacterial transfer, the kiss contact surface, and average saliva volume. As it turns out, a total of 80 million bacteria are transferred during a 10-second kiss.

These findings were used to help design the “Kiss-O-Meter” at Micropia, a museum of microbes in Amsterdam where this data can be put to the test.

]Photo from flickr user Rev. Xanatos Satanicos Bombasticos ]