A simple bath or a swim in the sea of just a few minutes is enough to temporarily alter the skin microbiome, but in a quite evident way according to interesting research presented at the annual meeting of the American Society for Microbiology.
According to Marisa Chattman Nielsen, a student at the University of California, Irvine, lead author of the study, exposure to ocean water can alter the diversity and composition of the human skin microbiome, although the latter appears to return to its initial condition after several hours.
The experiment was carried out on nine participants who carried out a 10-minute swim monitored by the same researcher who took into account various factors. The beach met the criteria regarding the possibility of not being able to use a sunscreen while the participants had a history of sporadic swimming in the sea. Furthermore, the same participants had not immersed themselves in seawater during the 12 hours prior to the experiment and had not taken antibiotics in the previous six months.
The researcher and her colleagues followed a swab on the back of the calf of the participants in the experiment before they entered the water and after they had come out and dried completely in the sun. Additional swabs were then performed after six hours and 24 hours after the swim.
Before the swim, the participants showed different microbial communities on their skin but after the swim they all had similar communities, completely different from the previous communities.
Six hours after entering the water, the microbiomes of the skin seemed to return to the pre-swim composition. 24 hours after the swim the composition was almost similar to the one before the swim.
Interesting results saw the presence of bacteria of the genus Vibrio on the skin of the participants not only after they had dried but also six hours after the swim (24 hours later they were present only on one individual).
It is a demonstration of the fact that possible species of pathogenic vibrios could potentially persist on the skin even several hours after swimming, which actually increases the vulnerability of the human body to infections with regard to contact with seawater.