Communication Dans Un Congrès Année : 2023

Antimicrobial susceptibility of isolates of Aeromonas spp. collected in a french river impacted by terrestrial and aquatic farming activities: a 17 months following up

Résumé

The “Resist3A” project aimed to determine the occurrence of AMR upstream and downstream of two trout fish farms, located respectively at the source (FF1) and at the mouth (FF2) of a river influenced by agriculture, terrestrial farming and a wastewater treatment plant. Every two weeks for 17 months, water samples were collected upstream and downstream of the two fish farms and biofilm samples were collected in the same pond per farm. In total, of 144 water samples and 72 biofilm samples were collected. In addition, raw and treated wastewater samples were collected from three wastewater treatment plants connected to the river (13 raw wastewater and 16 treated effluent samples). Antimicrobial susceptibility testing of a selection of 355 Aeromonas (water samples n=172; biofilm n=183), was performed by agar diffusion according to CLSI. Antimicrobial agents tested included (i) eight antibiotics which are critical for human health (WHO list and those used to treat human infections): piperacillin, amoxicillin-clavulanic acid, ceftazidime, cefepime, ciprofloxacin, gentamicin, amikacin and tobramycin and (ii) six agents of interest in aquaculture according to CLSI: chloramphenicol, florfenicol, enrofloxacin, oxolinic acid, oxytetracycline and trimethoprim-sulfamethoxazole. In addition, integrons known to be associated with anthropic pressure were detected by qPCR in the 355 isolates from the river and from the 252 isolates collected from raw wastewater (n=127) and treated wastewater (n=125). From source to the mouth in water samples, no decrease in susceptibility was observed for oxolinic acid, florfenicol, oxytetracycline, ceftazidime. On the contrary, a slight decrease in susceptibility was observed for enrofloxacin. Isolates collected in the biofilm of the FF1, showed a reduced susceptibility to oxytetracycline and oxolinic acid. No reduction in susceptibility was observed for isolates collected in the FF2 biofilm. Integrons (esp. class 1 integron) were detected in 18.5% (n=693) of the tested isolates. Three isolates recovered from raw wastewater harbored both class1 and 2 integrons. In raw wastewater the frequency of integron detection was almost three-times higher than in treated effluents (14.5% vs 6.4%), representing the acquisition of genetic material from the environment or other bacteria (horizontal gene transfer). Integron detection was significantly higher in isolates of waters collected at the mouth of the river than those collected at its source, 27.9% (n=27/86) and 1.2% (n=1/82), respectively, leading to the assumption that mobile genetic elements were steadily incorporated into isolate genomes as a consequence of natural or artificially associated evolution processes. In biofilms FF1 (24.8%, n=30/121) and FF2 (30.3%, n=46/152), no significant differences were observed (p< 0.31). The notified results are in agreement with the increasing anthropic pressure from the source to the month of the river. While the AMR situation in the investigated ecosystem currently seemed to be only slightly influ- ences by the used antimicrobials, the tolerance of bacteria against them may increase steadily over time of exposure. Furthermore, artificial pollutants may also influence the natural competence and the rate of the evolution of the bacteria potentially leading to a development of emerging pathotypes.
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anses-04168500 , version 1 (21-07-2023)

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  • HAL Id : anses-04168500 , version 1

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Sandrine Baron, Laetitia Le Devendec, Emeline Larvor, Duprey Héloïse, Eric Jouy, et al.. Antimicrobial susceptibility of isolates of Aeromonas spp. collected in a french river impacted by terrestrial and aquatic farming activities: a 17 months following up. 13. International Symposium on Aeromonas and Plesiomonas (ISAP), Jun 2023, Wroclaw, Poland. ⟨anses-04168500⟩

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