Perhaps it's not too much of a surprise to learn that there's a strong correlation between spending time in not-particularly-clean water and exposure to antibiotic-resistant bacteria. This is the revelation of a study presented Monday at the Society for General Microbiology's Annual Conference, which estimates that swimmers, surfers, and other folks splashing around in the waters off England and Wales ingested antibiotic-resistant strains of Escherichia coli more than six million times in 2012.
The estimate is based on water samples taken from "coastal bathing waters" and varying estimates of incidental or accidental water swallowing involved with different water sports, including swimming and surfing.
According to the paper from a team at the University of Exeter Medical School, antibiotic-resistant E. coli is a reasonably rare phenomenon, accounting for about .12 percent of all E. coli found in the coastal waters in question. This becomes nontrivial with more exposures, which is a product of both the type of water activity and its frequency. For example, a surfer will certainly ingest more water and more resistant bacteria than a kayaker.
The strains of E. coli covered in the study are actually resistant to a whole class of antibiotics known as the third-generation cephalosporins. These are some of the most popular (overpopular, really) antibiotics out there, and this makes them especially vulnerable to emerging resistance.
E. coli, meanwhile, is a classic example of two-faced bacteria, with some strains existing harmlessly in the human gut and other virulent strains posing real dangers to humans in the form of food poisoning and diarrhea, as well as gnarlier stuff like bacterial pneumonia, urinary tract infections, and beyond. E. coli also happens to be rather adept at passing its own developed antibiotic resistance to bigger villains like Staphylococcus aureus through a process known as horizontal gene transfer.
"We know very little about how the natural environment can spread antibiotic resistant bacteria to humans, or how our exposure to these microbes can affect health," offered co-author William Gaze in a statement. "People are exposed to antibiotic resistant bacteria in many ways, through person-to-person contact, via food and as a result of international travel."
"Our research establishes recreational use of coastal waters as an additional route of exposure," Gaze said. "With millions of people visiting beaches in England and Wales each year, there is a risk of people ingesting 3GC resistant E. coli, and it looks like water-users' exposure to all resistant bacteria could be even higher."
Crucially, what's missing from Gaze's research—and will be explored in future work—is how that additional exposure actually impacts the health of surfers and swimmers. Are they actually getting sick in larger numbers? The increased exposure suggest that they should be, but for now that remains just a suggestion. At the very least, the work offers a new perspective on the problem and its ever increasing inescapability.
The paper, titled "Human recreational exposure to antibiotic resistant bacteria in coastal bathing waters," is set to be published in Environment International; an abstract is available through the SGM 2015 site.