How long does it take for bacteria to colonize our skin? Evidently, for ocean bacteria, it takes just 10 minutes of swimming to alter our skin microbiota.

Swimming In The Ocean

Exposure to ocean water is only natural during the summer months, but according to a new study just 10 minutes of swimming is enough for ocean bacteria to colonize the skin. Researchers discovered this after conducting an experiment at the beach.

For the study presented at the annual meeting of the American Society for Microbiology, researchers focused on a group of selected beach goers. They chose ones who did not swim in the ocean too frequently, were not using sunscreen at the time, have not bathed in the last 12 hours, and have not taken any antibiotics in the past six months.

The participants’ skin microbiomes were tested via a skin swab at the back of the calf before they went in for a swim, right after the 10-minute swim, six hours after, and again a day after.

Ocean Bacteria Colonization

Interestingly, the participants’ skin microbiomes were quite distinct from one another before they went in for a swim, but became very similar after just the 10-minute swim. That said, the changes were temporary, since by the six-hour mark, the participants’ skin microbiomes were beginning to look like the post-swim microbiomes, and by the 24-hour test, they were already far into the process.

What’s worrying, however, is not the amount of time that the participants’ skin microbiomes were altered and colonized by ocean bacteria, but the bacteria the researchers discovered on their skins. Upon testing, researchers found that while most of the bacteria were essentially harmless, they also discovered the presence of the Vibrio species, which includes the bacterium that causes cholera.

“While many Vibrio are not pathogenic, the fact that we recovered them on the skin after swimming demonstrates that pathogenic Vibrio species could potentially persist on the skin after swimming,” said lead author Marisa Chattman Nielsen, MS.

Further, researchers also note that the amount of Vibrio detected on human skin was 10 times greater than the amount they detected in the ocean water samples. This could mean that the species has an affinity to attach to human skin.

Skin Microbiome

Interestingly, the results of the current study actually line up with the pattern of how the beach-goers who swim are more likely to get infections soon after compared to those who just stay on the sand.
What’s more, recent studies have shown that skin microbiome is an important player in immunity and protection against infectious diseases.