13.01.2012

Mather et al (2011) Proceedings of The Royal Society

Antimicrobial resistance (AMR) presents a major and growing threat to effective treatment of bacterial infections. For almost a century, antimicrobials have been used to control bacterial infections and disease in humans and animals. However, with increasing microbial resistance to these drugs, despite current interventions, we face a return to nineteenth century levels of morbidity.
The use of antimicrobials in agriculture as a major driver of AMR in pathogenic bacteria of significance to humans is an issue over which opinions are divided. The prophylactic and metaphylactic use in animal populations has been a particular concern, especially when the drug classes are the same as, or related to, the pharmaceuticals used in the control of human infections. In addressing the basic tenet that the use of antimicrobials in animal populations is the major influence on the emergence and maintenance of resistance in human pathogens, three critical questions arise.

1. are the resistance phenotypes in human and animal microbial populations the same, and do they arise from common or distinguishable
microbial communities?
2. in which microbial population are the resistances and resistance profiles common to both animals and humans first identified?
3. can we identify the most probable origins of all resistance phenotypes recovered from human and animal populations, and thereby infer the directionality of resistance transmission in these microbial communities?

In this study, the researchers combine aspects of ecology and epidemiology, and show that animals and humans have distinguishable populations of resistance phenotypes, differing in prevalence, linkage and diversity of resistance. By examining the temporal ordering of first appearance, and phenotypic similarities of resistance profiles, they establish that the sympatric animal population is unlikely to be the major source of resistance diversity for humans.