Do seas make us sick? Surfers may have the answer

On a recent trip, Cliff Kapono hit some of the more popular surf breaks in Ireland, England and Morocco. He is proudly Native Hawaiian and no stranger to the hunt for the perfect wave. But this time he was chasing something even more unusual: microbial swabs from fellow surfers. Cliff, a biochemist earning his doctorate at the University of California, San Diego (UCSD), USA, heads the Surfer Biome Project, a unique effort to determine whether routine exposure to the ocean alters the microbial communities of the body, and whether those alterations might have consequences for surfers — and for the rest of us.

Cliff has collected more than 500 samples by rubbing cotton-tipped swabs over the heads, mouths, navels and other parts of surfers’ bodies, as well as their boards.

Volunteers also donate a faecal sample. He uses mass spectrometry to create high-resolution maps of the chemical metabolites found in each sample. Then, working in collaboration with UCSD’s Centre for Microbiome Innovation, Cliff and his colleagues sequence and map the microbes found on this unusually amphibious demographic. He and his colleagues are looking for signs of antibiotic-resistant organisms. Part of their aim is to determine whether, and to what extent, the ocean spreads the genes for resistance.

Many antibiotics used today derive from chemicals produced by microbes to defend themselves or to attack other microorganisms. No surprise, then, that strains of competing bacteria have also evolved the genetic means to shrug off these chemicals. While drug resistance comes about because of antibiotic overuse, the genes responsible for creating resistance are widely disseminated in nature and have been evolving in microbes for eons. Startlingly, that means genes giving rise to drug resistance can be found in places untouched by modern antibiotics.

A reservoir of resistant genes
Several years ago, researchers identified antibiotic-resistant genes in a sample of ancient permafrost from Nunavut, in the Canadian Arctic. William Hanage, an epidemiologist at the Harvard School of Public Health, USA, was among those showing that these genes conferred a resistance to amikacin, a semisynthetic drug that did not exist before the 1970s. “There was a gene that encoded resistance to it in something that was alive 6,000 years ago,” he said in an interview.

The ocean, home to an incredible diversity of dissolved chemistry, also acts as a reservoir for these genes, and researchers are trying to figure out if they move from the seas into the human population. So who better to study than surfers? “A lot of the research of the transmission of resistant bacteria has focused on the role of the health care environment,” said Anne Leonard, an environmental epidemiologist at the University of Exeter, UK who is investigating whether surfers have higher rates of bacterial colonisation. “What’s less well studied is the role that natural environments play.”

By some estimates, surfers can swallow about 170 milliliteres of seawater per session. Because bacteria readily pick up and pass on genetic information across species, researchers suspect the risks of acquiring resistant genes are higher in places that facilitate direct transfer with microbes inhabiting the body. Coastal waters polluted with sewage, in this view, are probably more worrisome than smog or deep caves.

At the moment, no one is sure whether it is actually possible for people to pick up these microbial genes from a long day at the beach. In the lab, however, Cliff has found evidence for the transfer of resistance genes from bacteria in the ocean into strains associated with the human gut when they are placed in proximity.

Evolutionary pressures favoured the emergence of resistant genes. Microbes are drawing upon this natural bank of resistance today to fend off the best drugs devised by humans. “These antibiotic resistance genes did not arise in order to make our lives awkward,” William said. “They have completely different functions that only have recently been repurposed.” “These things are everywhere,” he added. “If we want to stop them from moving into pathogens that are killing us, we need to understand where they are.”