SAN FRANCISCO – You can bring a few new friends home next time you take a swim in the sea. Researchers at the University of California have found that marine bacteria invade and alter the skin's microbiome after only 10 minutes for swimming, increasing the likelihood of infections.
Our skin is naturally home to millions of bacteria and fungi, and although this may sound a bit unnerving at first, these little stowways actually help regulate our immune system and protect us from unwanted pathogens and infections. This community of organisms is referred to as the microbiome of the skin.
"Our data demonstrates for the first time that the water impact of the sea can change the diversity and composition of the human skin microbiome," explains author Marisa Chattman Nielsen in a release. "While swimming, normal resident bacteria were washed away while sea bacteria were deposited on the skin."
This accumulation of ocean bacteria and subsequent alteration in the skin microbiome can leave swimmers more susceptible to infections and aggravate disease states. Examples include ear and skin infections and gastrointestinal or respiratory diseases.
The study's authors say the study was imposed due to previous studies that have already found a link between sea swimming and infections, and the unfortunate fact that more and more beaches are showing poor water quality due to waste and storm flow.
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Volunteers for this study should meet strict criteria for no sunscreen use, no bathing within the last 1
In total, nine swimmers were selected for the study. Each swimmer's calf was swabbed four times; once before entering the water again after drying after a 10 minute swim and again in six and 24 hours after swimming.
Each swimmer's microbiom changes dramatically after a 10-minute swim. In addition, all swimmers after swim microbiomas were very similar, indicating that each volunteer's microbiome was actually colonized by ocean bacteria. Over the next 24 hours, the swimmers' microbiomas almost returned to their original compositions. Ocean bacteria were only present on a volunteer after a full 24 hours.
Perhaps even more disturbing were some of the bacteria detected on swimmer's skin, more than 10 times greater than 19459006 than the fraction actually discovered in ocean water samples. This suggests that at least some ocean bacteria have an affinity for human skin.
This study was presented at the 2019 American Society for Microbiology Meeting.