9. Conclusions & recommendations
Biocides – including disinfectants, antiseptics, preservatives and sterilants – are invaluable chemicals that provide society with many benefits, keeping harmful micro-organisms at bay. They play an important role in the control of bacteria in many applications and are a precious resource that must be managed so that it remains effective for as long as possible.
Any situations where biocides are used extensively and regularly at concentrations too low to kill bacteria, can lead to increased antimicrobial resistance. This may happen for instance in hospitals, in food production, in cosmetic manufacturing, etc.
Resistance genes can be transferred from one bacterium to another and using biocides can lead to the preferred survival of bacteria with resistance genes. Many well-studied biocides lead to resistance by this mechanism but the role that less studied biocides play in inducing or maintaining antibiotic resistance is not known.
Some biocides are more likely to lead to resistance than others but it is hard to quantify the risk of increasing antibiotic resistance for each biocide and each application. In some situations where both antibiotics and biocides are used, it is not possible to discriminate the origin of antimicrobial resistance at this moment.
Standard methods of measuring resistance brought about by biocide use are not available and should be developed. The tests should measure the lowest concentration of biocide that can lead to resistance if it is used repeatedly at concentrations too low to kill bacteria. Environmental monitoring programmes for undesirable substances should include biocides. To enable the assessment of exposure, and thus the likelihood of resistance emerging, companies should be encouraged to report the volumes of biocides they produce or use.
Additional studies are needed to:
- understand the mechanisms of cross-resistance and the emergence of biocide-induced antibiotic resistance in different fields of application (e.g. health care, veterinary uses, food production, cosmetics and consumer products).
- develop standard methods to evaluate the ability of a biocide to cause or maintain antibiotic resistance.
- develop standard methods to identify/measure resistance, cross-resistance and multi-drug resistance.
- develop surveillance programmes to monitor the level of resistance, cross-resistance and multi-drug resistance of micro-organisms found in health care facilities, veterinary settings and the food industry.
- study exposures in order to identify and quantify the risks of resistance, cross-resistance and multi-drug resistance emerging in bacteria following biocide exposure.