Antibiotic resistance is spreading among marine mammals

A new study of seals and porpoises in the Salish Sea shows how antibiotic-resistant bacteria proliferate in coastal waterways.

 

One Friday afternoon in August, Stephanie Norman was performing a routine necropsy, hacking away at the remains of a large, pneumonia-stricken harbor seal, when she nicked herself with the scalpel. She thought nothing of it until she woke up Sunday morning. “My finger was this big around,” she said later, making a circle the size of a silver dollar with her thumb and index finger. 

Norman, a veterinary epidemiologist, examines stranded seals and porpoises in the Salish Sea for antibiotic-resistant bacteria. Despite her injury, she rushed to the airport to travel to a research conference. But on the flight, her symptoms worsened: “The biologist sitting next to me said, ‘Do you know that you’ve got a red streak going up your arm?’ ” So, after she landed, Norman sought help at an urgent care clinic. Knowing her infection could be resistant to antibiotics, she was nervous. 

Each year, around 2 million people in the U.S. develop antibiotic-resistant infections, and 23,000 of them die as a result. Scientists need to understand how resistant bacteria travel to control their spread, but that path is far from straightforward. To illuminate the pathways among humans, pets, and livestock to wild animals, researchers must collect samples from a variety of species, including those that live in the ocean.

Of 28 seals tested in the Salish Sea, about half of them harbored antibiotic-resistant bacteria.
Ian Macrae Young/Alamy

But sampling marine animals, especially wild ones, is hard. Taking a swab from a creature’s body requires removing it from the water, which disturbs the animal and requires significant time and effort. As a result, there are only a handful of studies on resistant bacteria in wild marine animals and resistant bacteria, leaving scientists with an incomplete picture of how superbugs spread in coastal waterways. 

To remedy that, Norman is enlisting help from volunteers who respond to stranded marine mammals around the Salish Sea. They take samples from fresh dead seals and porpoises, which are analyzed for resistance to 16 antibiotics. They bring some carcasses to Norman for necropsies, which provide clues about the animals and their potential exposure to resistant bacteria: what they ate, how they died and any contact they may have had with human-made materials, like fishing lures. 

Resistant bacteria might also be latent in the water, partly due to the aquaculture industry’s use of antibiotics. The FDA has authorized three antibiotics to treat ailing fish, which are related to medications also used to treat humans. The treatments, dumped into the water directly or via fish food, easily disperse from open pens; a 2013 study estimated that 80% of aquaculture medications make their way into the greater environment. These trace amounts stimulate the growth of resistant bacteria by killing off all but the hardiest strains. Those bacteria can then afflict wildlife and sometimes even find their way back to land, infecting humans. In Washington, studies from as early as 1992 show resistant bacteria proliferating around commercial Atlantic salmon pens.

Other potential sources include sewage, agriculture and stormwater runoff. Tracking superbugs in the ocean as well as on land will provide a clearer picture of how they spread and perhaps suggest ways to minimize transmission. Norman’s test results will be entered into the archives at ARMADA, a nonprofit organization building a database of antibiotic-resistant gene data for researchers. Evgeni Sokurenko, a University of Washington microbiologist on the organization’s advisory board, said this information could help researchers stop bacterial outbreaks before they start. “If you imagine bacterial strains as criminals, what we’re doing is creating a database of these criminals so they can be caught, and (we can) figure out where they’re coming from,” he said.

So far, Norman and her team have collected samples from 28 seals and 10 porpoises. About half carried resistant bacteria, while a sizable portion — half the porpoises and a quarter of the seals — also harbored what Sokurenko calls “nightmare bugs”: bacteria that are resistant to more than one antibiotic, and thus less treatable by the medications doctors and vets typically use. These strains were resistant to ciprofloxacin and third-generation cephalosporins, medications commonly used to treat a wide range of infections in humans. That’s “quite unusual for wildlife,” said Sokurenko.

Norman’s goal is to sample 130 marine mammals by the end of the year. One project can’t unravel all the intricacies of how antibiotic-resistant bacteria spread, but Norman hopes her samples yield some answers. After all, ocean health and human health are inextricably linked, she said. “It’s a two-way street.”

Her finger infection in August drove this home. At first, Norman didn’t know which bacteria was the culprit — just that it came from an ill seal that may have harbored resistant bacteria. “Wow, that’s concerning,” the clinic nurse told her. Together, they decided on two antibiotics, hoping at least one might work: a shot of cephalosporin and a course of doxycycline. A week later, the seal’s lab results came back: It was a type of resistant E. coli, which, luckily, was not resistant to doxycycline — and Norman’s finger was healing nicely.

Jane C. Hu is an independent journalist who writes about science, technology, and the outdoors. She lives in Seattle.

 Email High Country News at [email protected] or submit a letter to the editor.

High Country News Classifieds
  • INDIGENOUS AFFAIRS EDITOR
    High Country News seeks an editor to oversee the work of our award-winning Indigenous Affairs Desk. This individual will lead a team of passionate journalists...
  • HIKING TO THE EDGE:
    Confronting Cancer in Rocky Mountain National Park. Poetry and photos on survival thinking. E-book and paperback available at Amazon.com.
  • OPERATIONS MANAGER
    Founded in 1936, the National Wildlife Federation has grown into America's largest and most trusted grassroots conservation organization with 53 state/territorial affiliates and more than...
  • IPLC RIGHTS AND EQUITY PROGRAM ASSOCIATE
    A LITTLE ABOUT US Founded in 1951, the Nature Conservancy is a global conservation organization dedicated to conserving the lands and waters on which all...
  • EXECUTIVE DIRECTOR FUTURE WEST
    Future West seeks an executive director to lead this dynamic organization into the future. Based in Bozeman, MT this well-respected nonprofit provides communities in the...
  • PART-TIME EXECUTIVE DIRECTOR
    Mitchell Museum of the American Indian Location: Evanston, IL Salary Range: $45,000 @ 24 hours per week. send resume: [email protected] www.mitchellmuseum.org
  • COMMUNICATIONS LEAD
    Southeast Alaska Conservation Council is hiring! Who We Are: The Southeast Alaska Conservation Council (SEACC) is a small grassroots nonprofit based out of Juneau, Alaska,...
  • SENIOR POLICY ADVISOR
    Since 1989, The Nature Conservancy in Alaska has been doing work you can believe in protecting the lands and waters that all life depends on....
  • OUTDOOR PROGRAM - ASSISTANT DIRECTOR
    St. Lawrence University seeks to fill the position of Assistant Director in the Outdoor Program. To view the complete position description, including minimum qualifications required,...
  • PUBLIC LANDS DIRECTOR
    Job Announcement Conserve Southwest Utah is seeking a dedicated advocate for conservation and public lands Public Lands Director a "make a difference" position Conserve Southwest...
  • FOR SALE
    Yellowstone Llamas Successful Yellowstone NP concession Flexible packages
  • DIRECTOR OF DEVELOPMENT & MARKETING
    Grand Staircase Escalante Partners is seeking a full-time Director of Development & Marketing. This is a senior position responsible for the development of all marketing...
  • LEGAL DIRECTOR
    The Legal Director will work closely with the Executive Director in cultivating a renewed vision at NMELC that integrates diversity, equity, and justice. Black, Indigenous,...
  • VICE PRESIDENT, LANDSCAPE CONSERVATION
    The Vice President for Landscape Conservation leads Defenders' work to promote landscape-scale wildlife conservation, focusing on four program areas: federal public lands management; private lands...
  • NOVA SCOTIA OCEAN FRONT
    Camp or Build on 2+ acres in Guysborough. FSBO. $36,000 US firm. Laurie's phone: 585-226-2993 EST.
  • COMMUNITY FORESTER
    The Clearwater Resource Council located in Seeley Lake, Montana is seeking a full-time community forester with experience in both fuels mitigation and landscape restoration. Resumes...
  • GUNNISON BASIN ROUNDTABLE
    The Gunnison Basin Roundtable is currently accepting letters of interest for ten elected seats. Five of the elected members must have relevant experience in the...
  • PCTA TRAIL CREW TECHNICAL ADVISORS IN WASHINGTON'S NORTH CASCADES
    Seasonal Positions: June 17th to September 16th (14 weeks) - 3 positions to be filled The mission of the Pacific Crest Trail Association is to...
  • WE'RE LOOKING FOR LEADERS!
    As we celebrate 50 years of great Western journalism, High Country News is looking for a few new board members to help set a course...
  • WIND RIVER WRITERS AND PHOTOGRAPHERS RETREAT BY THE NATIONAL BIGHORN SHEEP CENTER
    Enhance your writing or photography skills with world-class instructors in the beautiful Wind River Mountains. All skill levels welcome. Continuing education credits available.