Implications of antibiotic resistance for drinking water production

More knowledge needed

AMR (antimicrobial resistance) – consisting of AB (antibiotics and metabolic products), ARB (antibiotic-resistant bacteria) and ARG (antibiotic-resistant genes) – is one of the major threats to public health in the time to come. The fact that more and more micro-organisms are becoming resistant to a range of antibiotics means that bacterial infections that used to be easy to treat can now actually be fatal. Antibiotic resistance is not a problem of the future but a growing problem that is with us now. Antibiotic-resistant bacteria are expected to be the number-one cause of death by 2050.

Since the economic impact of antibiotic resistance is also enormous, this issue is becoming an increasingly prominent item on the agenda, not only with end users but also with politicians. The water chain plays a role as well. Here, the concern is about discharges of antibiotic resistance into the water environment, the transport of resistance genes into the water and soil, and exposure to resistance genes via water (drinking, bathing, irrigation of food crops, aquaculture). Resistance genes, including those against the latest generation of antibiotics, and Highly Resistant Micro-Organisms (HRMO) are, as shown recently in a presentation by RIVM/STOWA, found in Dutch sewage water, surface water and soil. The water environment is therefore both a reservoir and melting pot for antibiotic resistance.

In the Netherlands, we have quite a number of barriers to HRMO and ARG in our drinking water supplies and human exposure via drinking water is probably low by comparison with other routes such as food. However, keeping the water system healthy in our country, which is densely populated with people and farm animals, is a major challenge. We therefore need to know more about pollution sources, distribution routes, prevention and behaviour and, above all, about the removal of ARG by treatment processes in the water chain, because this is where possible control measures are to be found.

This project investigates to what extent antibiotic resistance is present in the system of drinking water supply, from source to tap, and the role of treatment processes. The level of exposure through drinking water is then compared with other routes.

Survey of antibiotic resistance and effects of treatment processes

A survey is being made of clinically relevant ARG and HRMO present in (1) untreated water, (2) after treatment processes, (3) in the distribution network and (4) in drinking water. This information is used to determine any implications for drinking water production.

The study is also looking at how, and to what extent, HRMO and ARG are removed from drinking water by treatment processes, and at whether ARG concentrations actually increase in certain treatment processes.

Drinking water compared with other exposure routes

As a result of this project, an accurate assessment can be made of the possible risk of people in the Netherlands being exposed to clinically relevant ARG via drinking water by comparison with other routes such as food. This makes it possible to place drinking water in the right context with respect to the relevant risks.

Influences and transmission routes of human and veterinary use of antibiotics in the water cycle.