Surfers in the UK are three times more likely to have antibiotic-resistant E coli bacteria in their gut than other people, a new study reveals.
Researchers also found that people who regularly surf or bodyboard in the UK's coastal waters were four times as likely to harbour bacteria containing genes that make them resistant to antibiotics.
In the Beach Bums study, conducted by the University of Exeter, 300 people, half of who regularly surf the UK coastline, were asked to take rectal swabs.
Surfers swallow 10 times more sea water than sea swimmers. Scientists researched whether swallowing sea water made them more vulnerable to bacteria that pollute seawater, and whether those bacteria are resistant to an antibiotic.
Fecal samples were taken from surfers and non-surfers to assess whether the surfers' guts contained E coli bacteria that could grow in the presence of cefotaxime, a commonly used and clinically important antibiotic.
Cefotaxime had earlier been prescribed to kill off these bacteria, but a number of bacteria have acquired genes that enable them to survive the treatment.
According to the study published in the journal Environment International, 13 out of 143 surfers (9 per cent) were colonised by the resistant bacteria, as against only four out of 130 of non-surfers swabbed (3 per cent).
That meant the bacteria would continue to grow even if treated with cefotaxime.
Further, the researchers found that regular surfers were four times more likely to have the bacteria containing mobile genes capable of making bacteria resistant to the antibiotic.
Anne Leonard, who led the research, said the study "is the first of its kind to identify an association between surfing and gut colonization by antibiotic resistant bacteria."
According to the researchers' estimates more that 2.5 million water sports sessions took place in England and Wales in 2015, which led to ingestion of E. coli bacteria.