infections

Swimming in the ocean alters the microbiome skin and may increase the likelihood of infection, according to research presented at ASM Microbe 2019, the annual meeting of the American Society for Microbiology.

“Our data,” said Marisa Chattman Nielsen, a Ph.D. student at the University of California, Irvine, and lead author of the study, “are very good. demonstrate for the first time that exposure to ocean water can alter the diversity and composition of the human skin microbiome. We have observed that while swimming, normally resident bacteria are washed away while ocean bacteria are deposited on the skin.”

The researchers found the ocean bacteria on all study participants immediately after swimming and air-drying their bodies, but also after six hours and even after one day; however, there were differences and some acquired more ocean bacteria than others or retained them longer.

This is not just curious news, because previous studies had already shown associations between ocean swimming and infections, and many U.S. beaches bordering the Pacific Ocean are washed by poor-quality water due to sewage runoff and rainwater. Recent research has shown that changes in the microbiome can increase susceptibility to infection and influence disease states. Exposure to these waters can cause gastrointestinal and respiratory diseases, ear and skin infections.

The research was conducted on nine volunteers without sunscreen, who had previously been exposed only sporadically to ocean waters, who had not bathed in the past 12 hours, and who had not taken antibiotics in the previous six months.

The most frequently detected ocean bacteria include those of the genus Vibrio; the researchers did not specify the species found, but Nielsen said, “Many Vibrio are not pathogenic, but our research shows that pathogenic species could potentially persist on the skin after swimming.”

Indeed, the fraction of Vibrio detected on human skin was more than 10 times higher than that found in ocean water samples, suggesting a specific affinity that determines its attachment to human skin.

ASM Microbe is the annual meeting of the American Society for Microbiology, which This year it was held from June 20 to 24 in San Francisco, California.