It is a fundamental law of nature that any chemical that results in the reduction in growth or the killing of a microbe will ultimately drive natural selection towards ‘solutions.’ A conservative estimate suggests that 13% of all biomass on earth are microbes (8). Their short generation time, relative to macroorganisms, helps ensure their adaptation to any chemical challenge. Microbial adaptation to chemical antagonism applies not only to antibiotics, but also to ‘natural’ pollutants such as metals (e.g. Zn, Cd, Ni, Cu) and plant secondary metabolites (9, 10).
All microorganisms harbour resistance genes, without which they would have no ‘immune system’. Some of the resistance genes are clinically important, while most afford a basic level of protection. The problem arises when clinically-relevant resistance genes are shared. Microorganisms acquire resistance genes through a range of genetic mechanisms termed mobile genetic elements. Without mobile genetic elements, the challenge of tackling AMR would be considerably easier.