Integrons from Aeromonas isolates collected from fish: A global indicator of antimicrobial resistance and anthropic pollution

Antimicrobial resistance (AMR) is now considered to be a major public health issue. AMR needs to be tackled following a One Health approach. With regard to antibiotic use and anthropic activity, fish farming is an appealing model to study the effects of antibiotic exposure on the rise of AMR. Aeromonas is at the interface of all the One Health components and represents an ideal test case in the One Health approach. Integrons which are genetic elements observed in Gram-negative bacteria are considered as a good proxy to monitor AMR dissemination. Here, we propose that Aeromonas from fish and integrons, could provide a consistent marker, when combined, of the level of acquired AMR in the environment.To investigate the link between integrons among Aeromonas from fish and anthropic pollution, we determined integron prevalence in a unique collection of Aeromonas isolates recovered from wild fish (WF), farmed fish (FF) and diseased fish (DF). The search for integrons from Aeromonas was performed using qPCR. Minimum Inhibitory Concentrations (MICs) were determined for the antibiotics commonly used in aquaculture and compared between integron-positive and integron-negative Aeromonas.Out of 379 non-redundant isolates, 69 Aeromonas harboured integrons. The proportion of integron-positive Aeromonas was significantly higher in the DF collection (34/70, 48.6%) compared to the FF collection (35/ 231, 15.2%) (p & LE; 0.001) whilst no integrons were detected among the 231 Aeromonas isolates of the WF collection. A significant link between integrons and MICs was observed for tetracycline, trimethoprimsulfamethoxazole and flumequine. Following a One Health approach, this study proposes the combination of two well-known biomarkers of AMR, integrons and Aeromonas collected from fish, as a novel potential indicator of AMR and anthropic pollution in the environment.

Automated summary

Antimicrobial resistance (AMR) is a major public health issue that needs to be addressed using a One Health approach. Fish farming provides an appealing model to study the effects of antibiotic exposure on the rise of AMR. Aeromonas and integrons are proposed as consistent biomarkers of AMR and anthropic pollution in the environment.