Aquaculture encompasses several types of farming, including fish farming, shellfish farming (oysters, mussels, clams, cockles, etc.), algae farming (seeweed), and crustacean farming (primarily shrimp and crayfish). Rising water temperatures in certain regions favour the growth of bacteria within this industry.
Antibiotics are only used to treat existing infections.
There is therefore a risk:
- Effluents from these farms can contain unmetabolised antibiotics and resistant bacteria which are released into the water. In contaminated aquatic environments, resistance genes can be transferred between aquatic bacteria and human bacteria.
- The ingestion of contaminated water or consumption of aquatic animals or seafood contaminated with resistant bacteria can lead to the temporary presence of resistant bacteria in the human digestive tract. This presence can become permanent if our microbiota is altered.
The effect on the human microbiome of consuming or ingesting water or food contaminated with antibiotic residues remains difficult to measure at the current time.
The aquaculture industry can limit the spread of antibiotics and resistant bacteria:
- By targeted use of antibiotics, with appropriate molecules prescribed by a veterinary surgeon, and regular use of antibiograms to define treatment
- By correct management of farms to limit infections through biosecurity measures, monitoring of bacterial flora in farms, vaccination of fish (injection, bath vaccination, oral vaccination), strengthening of immunity (vitamins, nutrients), monitoring of water quality, facility hygiene, limiting population density in tanks, improving animal welfare to reduce the risk of disease
- By wastewater treatment through the installation of filtration and wastewater treatment systems before wastewater is discharged into the environment (holding and settling tanks prior to discharge)
- By monitoring aquaculture farms for the presence of antibiotics and resistant bacteria; participation in a programme for the observation and monitoring of the main diseases
- By training farmers in the use of different treatments, including antibiotics