Emerging Trends in Antimicrobial Resistance in Polar Aquatic Ecosystems.

The global spread of antimicrobial resistance (AMR) threatens to plummet society back to the pre-antibiotic era through a resurgence of common everyday infections' morbidity. Thus, studies investigating antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) in urban, agricultural, and clinical settings, as well as in extreme environments, have become increasingly relevant in the One Health perspective. Since the Antarctic and Arctic regions are considered amongst the few remaining pristine environments on Earth, the characterization of their native resistome appears to be of the utmost importance to understand whether and how it is evolving as a result of anthropogenic activities and climate change. In the present review, we report on the phenotypic (e.g., disk diffusion test) and genotypic (e.g., PCR, metagenomics) approaches used to study AMR in the aquatic environment of polar regions, as water represents one of AMR main dissemination routes in nature. Their advantages and limits are described, and the emerging trends resulting from the analysis of ARB and ARGs diffusion in polar waters discussed. The resistome detected in these extreme environments appears to be mostly comparable to those from more anthropized areas, with the predominance of tetracycline, β-lactam, and sulfonamide resistance (and related ARGs). Indeed, AMR is, in all cases, more consistently highlighted in sites impacted by human and wildlife activities with respect to more pristine ones. Surprisingly, aminoglycoside and fluroquinolone determinants seem to have an even higher incidence in the Antarctic and Arctic aquatic environment compared to that from other areas of the world, corroborating the need for a more thorough AMR surveillance in these regions.