San Francisco, CA – June 22, 2019 – Ocean swimming is altering the skin microbiome and may increase the likelihood of infection, as demonstrated at ASM Microbe 2019, the annual meeting of the American Society for Microbiology.  "Our data shows for the first time that exposure to seawater can alter the diversity and composition of human skin microbiome," said Marisa Chattman Nielsen, MS, a PhD student at the University of California at Irvine, the lead author of the study. During swimming, normal bacteria were washed off while marine bacteria deposited on the skin. "
The researchers detected marine bacteria in all participants after air-drying, six and 24 hours after swimming, but some participants had acquired more marine bacteria and / or allowed them to persist longer.
Research was motivated by previous studies, the correlations between marine life and infection, as well as the high prevalence of poor water quality on many beaches due to sewage and rainwater runoff Recent research has shown that changes in the microbiome can make the host susceptible to infection and affect disease states Exposure to these waters can be gastrointestinal ̵
The researchers looked for 9 volunteers at a beach who did not use sunscreen, was rarely exposed to the sea, was not bathed in the past 12 hours, and had no antibiotics g in the last six months. The researchers dabbed the participants on the calf back before entering the water and again after the subjects were completely air-dried after a ten-minute swim and six and 24 hours after swimming.
Before swimming, all individuals had different symptoms of each other's communities, but after swimming they all had similar communities on their skin that were completely different from the "pre-swimming" communities. Six hours after swimming, the microbiomas had begun to return to their pre-swimming composition, and after 24 hours, they had progressed well in this process.
"A very interesting finding was that Vibrio species – identified only at the genus level – were detected by each participant after swimming in the sea and air-drying," said. Nielsen. (The genus Vibrio includes the bacterium that causes cholera.) Six hours after swimming, they were still present in most volunteers, but until 24 hours, they were only present in one person.
"While many Vibrio are non-pathogenic, the fact that we salvaged them after swimming on the skin shows that pathogenic Vibrio species may possibly remain on the skin after swimming," Nielsen said. The proportion of Vibrio species detected on human skin was more than 10 times higher than that in the ocean water sample, suggesting a specific affinity for attachment to human skin.
Skin is the body's first line of defense, both physical and immunological, while exposed to contaminated water. "Recent studies have shown that the microbiome of human skin plays an important role in the functioning of the immune system, in localized and systemic diseases and in infections," said Nielsen. "A healthy microbiome protects the host from colonization and infection by opportunistic and pathogenic microbes."
ASM Microbe is the annual meeting of the American Society for Microbiology, June 20-24 in San Francisco, California.
The American Society for Microbiology is the largest single life sciences company composed of more than 30,000 scientists and health professionals. The mission of ASM is to promote and develop microbial sciences.
ASM promotes microbial sciences through conferences, publications, certifications and educational opportunities. It expands laboratory capacity worldwide through training and resources. It offers a network for scientists from science, industry and clinic. In addition, ASM promotes a deeper understanding of microbial science for a broad audience.
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