Aim The current study was conducted to determine the antimicrobial resistance profile and genetic relatedness of Aeromonas sp. isolated from healthcare and urban effluents, wastewater treatment plant (WWTP) and river water. Methods and Results We detected the presence of genes conferring resistance to β‐lactam, quinolone and aminoglycoside. Multilocus sequence typing was carried out to differentiate the strains, and multilocus phylogenetic analysis was used to identify the species. A total of 28 cefotaxime‐resistant Aeromonas sp. strains were identified, harbouring uncommon Guiana‐extended‐spectrum (GES)‐type β‐lactamases (GES‐1, GES‐5, GES‐7 and GES‐16). Multidrug‐resistant Aeromonas sp. were found in hospital wastewater, WWTP and sanitary effluent, and A. caviae was identified as the most prevalent species (85·7%). Conclusion The release of untreated healthcare effluents, presence of antimicrobials in the environment, in addition to multidrug‐resistant Aeromonas sp., are all potential factors for the spread of resistance. Significance and Impact of the Study We identified a vast repertoire of antimicrobial resistance genes (ARG) in Aeromonas sp. from diverse aquatic ecosystems, including those that encode enzymes degrading broad‐spectrum antimicrobials widely used to treat healthcare‐associated infections. Hospital and sanitary effluents serve as potential sources of bacteria harbouring ARG and are a threat to public health.

25In the present study, we characterized antimicrobial resistance profile and genetic relatedness of 26 Aeromonas spp. isolated from healthcare and urban effluents, wastewater treatment plant (WWTP), 27 and river water. We detected the presence of genes responsible for the resistance to β-lactam, 28 quinolone, and aminoglycoside. Enterobacterial Repetitive Intergenic Consensus PCR and multilocus 29 sequence typing (MLST) were carried out to differentiate the strains and multilocus phylogenetic 30 analysis (MLPA) was used to identify species. A total of 28 Aeromonas spp. cefotaxime-resistant 31 strains were identified that carried a variety of resistance determinants, including uncommon GES-32 type β-lactamases. Multidrug-resistant Aeromonas spp. were found in hospital wastewater, WWTP, 33 and sanitary effluent. Among these isolates, we detected A. caviae producing GES-1 or GES-5, as 34 well as A. veronii harboring GES-7 or GES-16. We successfully identified Aeromonas spp. by using 35 MLPA and found that A. caviae was the most prevalent species (85.7%). In contrast, it was not 36 possible to determine sequence type of all isolates, suggesting incompleteness of the Aeromonas spp. 37 MLST database. Our findings reinforce the notion about the ability of Aeromonas spp. to acquire 38 determinants of antimicrobial resistance from the environment. Such ability can be enhanced by the 39 release of untreated healthcare effluents, in addition to the presence of antimicrobials, recognized as 40 potential factors for the spread of resistance. Thus, Aeromonas spp. could be included as priority 41 pathogens under the One Health concept. 42 43 IMPORTANCE 44