Antimicrobial Resistance: Is It A One Health Issue?

Abstract

Antimicrobial resistance (AMR) constitutes a serious threat to public health by rendering bacteria, previously susceptible to antimicrobials, resistant to their effects. Recent reports indicate that a considerable amount of human deaths is associated or even directly attributable to antimicrobial-resistant bacterial infections. Bacteria can become resistant because of spontaneous mutations or horizontal acquisition of antimicrobial resistance genes (ARGs) from exogenous sources. Horizontal transfer of ARGs can occur via mobile genetic elements (MGEs), such as plasmids, transposons or bacteriophages and this way, interspecies dissemination of ARGs can occur. Use of antimicrobials constitutes a well-described driver of AMR because it applies selection pressure on bacteria. Importantly, high amounts of antimicrobials are being used in livestock, which has caused concern on potential inter-host zoonotic transmission of AMR strains or ARGs. However, there are scarce evidence indicating transmission of AMR can happen between humans and animals, especially using robust methodologies. In this review, 19 papers employing whole-genome sequencing are presented on the basis of providing robust evidence (or not) of inter-host AMR transmission. In high-income countries (HICs), no or very limited evidence were identified. Comparably, more studies reported such events in upper-middle income countries (UMICs) and lower-middle income countries (LMICs), possibly because of a higher use of antimicrobials and closer contacts between humans and animals. Horizontal transfer of ARGs via MGEs appeared to play an important role in these events. Future studies should follow longitudinal, systematic sampling across both sectors to shed more light into the frequency and speed of this occurrence globally.