Ocean swimming changes Skin Microbiome and raising your risk of infections

Skin, the human body’s largest organ, is our first line of defense against infection and pathogens. The skin’s gut microbiomes that live on the surface of our skin play an important role in these defense measures.

Now, researchers from the University of California, Irvine, found that only 10 minutes of the swim in the ocean can temporarily change the skin’s microbiome and potentially increases the risk of infection.
Due to the wastewater runoff, pollution, and stormwater runoff, many beaches nowadays have poor water quality. And exposure to these harmful bacteria can cause skin infection, ear infection, stomach problems, and so on. Therefore, it becomes essential for an individual to understand how the skin’s bacteria changes when exposed to ocean water.

Marisa Chattman Nielsen, MS, a Ph.D. student and the lead author of the study said, our data demonstrate for the first time that ocean water exposure can alter the diversity and composition of the human skin microbiome. While swimming normal resident bacteria were washed off while ocean bacteria were deposited onto the skin.

For their study, the team went to the beach and selected nine people who met the criteria of no sunscreen use, infrequent exposure to the ocean, no bathing within the last 12 hours, and no antibiotics during the previous six months. Before they enter the water, the researchers swabbed the participants on the back of the calf and sent them to swim for 10 minutes. After they returned back and completely dried off, researchers swabbed their skin again, as well as at six and 24 hours post-swim.

They found that, before the swim, the microbiome of each volunteer was easily distinguishable. But after swimming, their microbiomes changed and became much more similar to one another, which were completely different from the “before swim” communities.

This change of the microbiomes community was temporary. The team says, after six hours of swimming, the microbiomes had begun to revert to their pre-swim composition, and at 24 hours, they were far along in that process.

But one very interesting finding was that Vibrio species, which were detected on each person’s skin. Most of these Vibrio species are essentially harmless, but some are responsible for diseases like cholera, or can rarely cause flesh-eating skin infections, especially in people with weakened immune systems. The team’s research was only able to detect the presence of Vibrio bacteria, not their specific species.

They found that bacterias were still present on most of the volunteers, even at six hours post-swim, but by 24 hours, they were present only on one individual. 

Nielsen said, while many Vibrio is 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.

The fraction of the Vibrio species detected on the participant’s skin was more than ten times greater than the fraction in the ocean water sample, suggesting a specific affinity for attachment to human skin, as per the researcher team.

Nielsen said, recent studies have shown that the human skin microbiome plays an important role in immune system function, localized and systemic diseases, and infection. A healthy microbiome protects the host from colonization and infection by opportunistic and pathogenic microbes.

The research presented at ASM Microbe 2019, the annual meeting of the American Society for Microbiology.