The potential of Aeromonas spp. from wildlife as antimicrobial resistance indicators in aquatic environments

Worldwide emergence of bacterial strains resistant to multiple classes of antimicrobials and the increase incidence of infections caused by bacteria resistant to last-resource antibiotics is now a common problematic and likely to increase in coming years. Surveillance of important resistant clones and associated mobile genetic elements is essential for decision-making in terms of mitigation measures to be applied for the prevention of such infections. However, the role of natural environments, and especially aquatic ecosystems that display optimal grounds for antimicrobial resistance (AMR) development and dissemination, as important components of the AMR cycle has been disregarded until recent years. It is now widely accepted that resistant strains and resistance determinants are disseminated in the aquatic environment and that resistance profiles are mainly shaped by anthropogenic environmental contamination. In light of the One Health concept, developing strategies for the monitoring of AMR prevalence and dissemination and unraveling critical points of action are required. Therefore, bacterial indicators and targeted vectors assume special importance in surveillance schemes. Aeromonas spp., a ubiquitous bacterial genus with importance as human, animal and food pathogens, are common in aquatic environments. Environmental isolates belonging to this genus often display acquired resistance determinants and their use as indicators to survey water quality and sewage pollution has been accepted. Wild animal species are also of highly importance in this context. They constitute potential AMR reservoirs in natural environments, as they actively participate in the dissemination of resistant bacteria and resistance determinants across habitats. Characterizing Aeromonas spp. retrieved from wildlife represents a potential aid for surveillance programs aiming at unraveling the intricate mechanisms of AMR evolution and dispersal in natural aquatic environments, as well as understanding possible consequences for human and animal health.