Oysters, antimicrobial resistance and us

The issue of wastewater treatment and disposal is growing across the country, and nowhere more so than right here in Cornwall. While organisations like Surfers Against Sewage lobby against sewage discharge in our rivers and seas, researchers right here at the University of Exeter Penryn Campus are looking into the impact of blackwater on antimicrobial resistance and the connections between this, our environment and our health.

Blackwater is wastewater from bathrooms and kitchens that can contain all manner of contaminants, from your typical faeces and urine to more specific chemicals, microplastics, heavy metals and pathogens. The treatment and use of blackwater has many benefits, with much of it providing nutrient-rich substances for agriculture reducing the need for artificial fertilisers. But despite treatment, blackwater still contains l pathogens and levels of antibiotics, high enough to contribute to antibiotic resistance in bacteria. The result? The growing threat of antibiotic-resistant bacteria contaminating groundwater, rivers, lakes, agricultural land and eventually our seas due to wastewater runoff flowing into the ocean.

Professor William Gaze, Professor of Microbiology at the University of Exeter, leads a large research group focusing on the environmental dimensions of antimicrobial resistance associated with wastewater and its transmission into our coast. Antimicrobial resistance, that includes resistance to antibiotics by bacteria, is now being described as a silent pandemic, occurs when bacteria, fungus, viruses and parasites no longer respond to the antimicrobial medicines we use to treat them. They’re resistant to the drug and can therefore continue to exist and cause infection. The emergence of antimicrobial resistance is a threat to human activity, reducing our ability to treat common infections, and stop the spread of disease in livestock and crops threatening our food sources.

There is now a need to better understand the potential role that recreational water use (i.e., sea swimming, paddleboarding, surfing) plays in the transmission of antimicrobial resistance which is one aspect Will and his team are looking at. In one study it was found that when compared with non-bathers (those not using water recreationally), UK surfers were three times more likely to have antibiotic resistant E.coli in their gut. This suggests that water users could be a potential host for the spread of these antimicrobial resistant pathogens and be more likely to suffer from antibiotic resistant infections themselves.

The Fal and Helford can have pollution problems like anywhere else on our coast, however the presence of oysters has presented Will and his team with an opportunity. Oysters are filter feeders. On average 200 liters of water passes through the gills of the oyster per day, and as it does so the oyster extracts any nutrients. But sometimes other substances get retained, including microbes that could be resistant to medical treatments. PhD student izzy Smith is looking at the oysters to see what pathogens are building up in the shellfish and are therefore in our waters. But don’t fear a tasty oyster, before being eaten they go through a process of cleaning and purging where any microbes would be expelled. The team are also looking at whether there is evolution of antibiotic resistance and whether already existing resistance found in the marine environment can be transferred to human pathogens when they enter the water, enhancing the issue of resistance.

Understanding what is in our wastewater is just one step to understanding how it can impact our environment and our health. There is a need to better understand the role recreational water plays in antimicrobial resistance for our health and blue spaces and thanks to hard work and oysters in our local area, Will and his team are well on the way.

If you’re concerned about wastewater in your local area, take a look at Surfers Against Sewage’s real time water quality app: Real-time Water Quality App Makes Our Seas A Safer Place - Surfers Against Sewage. Also if you are an existing user of the Safer Seas and Rivers App and swim in the sea or are a wild swimmer in rivers please consider participating in University of Exeter research directly by completing one of two surveys which you can find at https://blueadapt.eu/surveys.

How you can help improve water quality and reduce the likelihood of antimicrobial resistance:

Stop the spread - Invasive Non-Native Species are spread by human activities and can cause environmental and economic damage. When leaving the water CHECK clothing and equipment for organisms and remove, then CLEAN with freshwater at home and leave to DRY before using again.
Black and Grey water from boats - Do not flush into the harbour. If you do not have a holding tank on board then please use onshore facilities. Holding tank emptying facilities are available at the Haven pontoons in Falmouth harbour.
Chemical and antifoul - Cleaning and antifouling a vessel beside or into any watercourse causes illegal pollution and can spread invasive species.
Litter - Please take your litter home with you and pick up aft er your dog.
Reduce your consumption – by reducing your own water use i.e. by flushing less or having shorter showers you will reduce the amount of waste water needing to be treated or that could end up in the environment.

Reporting Pollution Incidents
On land and going into water call the Environment Agency 24-hour Hotline 0800 80 70 60
To report a pollution incident at sea contact the Coastguard 01326 317575