The Role of Aquatic Ecosystems (River Tua, Portugal) as Reservoirs of Multidrug-Resistant Aeromonas spp.

Abstract

The inappropriate use of antibiotics, one of the causes of the high incidence of antimicrobial-resistant bacteria isolated from aquatic ecosystems, represents a risk for aquatic organisms and the welfare of humans. This study aimed to determine the antimicrobial resistance rates among riverine Aeromonas spp., taken as representative of the autochthonous microbiota, to evaluate the level of antibacterial resistance in the Tua River (Douro basin). The prevalence and degree of antibiotic resistance was examined using motile aeromonads as a potential indicator of antimicrobial susceptibility for the aquatic environment. Water samples were collected from the middle sector of the river, which is most impacted area by several anthropogenic pressures. Water samples were plated on an Aeromonas-selective agar, with and without antibiotics. The activity of 19 antibiotics was studied against 30 isolates of Aeromonas spp. using the standard agar dilution susceptibility test. Antibiotic resistance rates were fosfomycin (FOS) 83.33%, nalidixic acid (NA) 60%, cefotaxime (CTX) 40%, gentamicin (CN) 26.67%, tobramycin (TOB) 26.67%, cotrimoxazole (SXT) 26.67%, chloramphenicol (C) 16.67%, and tetracycline (TE) 13.33%. Some of the nalidixic acid-resistant strains were susceptible to fluoroquinolones. Multiple resistance was also observed (83.33%). The environmental ubiquity, the natural susceptibility to antimicrobials and the zoonotic potential of Aeromonas spp. make them optimal candidates for studying antimicrobial resistance (AMR) in aquatic ecosystems. Aquatic environments may provide an ideal setting for the acquisition and dissemination of antibiotic resistance because anthropogenic activities frequently impact them. The potential risk of multi- and pan-resistant bacteria transmission between animals and humans should be considered in a “One Health—One World” concept.

Molecular Epidemiology, Virulence Traits and Antimicrobial Resistance Signatures of Aeromonas spp. in the Critically Endangered Iberochondrostoma lusitanicum Follow Geographical and Seasonal Patterns

“…While the prevalence of multidrug resistant Aeromonas varies among studies, several authors report high levels of multidrug resistance in their surveys among this genus [24,62,69,98]. In a recent investigation with Aeromonas isolates collected from water samples in the river Tua (northern Portugal), Gomes et al [106] determined that 83.3% of the studied collection was multidrug resistant. Although it is alarming that about a third of the isolates in this study present a multidrug resistance phenotype, current results suggest that sampled locations might be under lower selective pressure than other streams in the national territory and abroad.…”

Closed Genome Sequence of an Environmental Aeromonas veronii Strain from California, United States, with an IncA/C Plasmid Carrying an Extended-Spectrum β-Lactamase Gene, bla VEB-3

“…Aeromonas bacteria are common in aquatic environments and may serve as reservoirs of antibiotic resistance genes (ARGs) ( 1 – 3 ). These ARGs are often associated with mobile genetic elements (MGEs) ( 4 ), which may facilitate their transfer to bacteria of clinical significance ( 5 – 7 ).…”

Genomic investigation unveils high-risk ESBL producing Enterobacteriaceae within a rural environmental water body

“…Numerous studies have highlighted the existence of antimicrobial resistant bacteria within pathogenic strains sourced from aquatic systems ( Li et al., 2020 ; Gomes et al., 2021 ; Conte et al., 2021 ), stressing the need for surveillance of AMR in the environment. Of most concern is the presence of Extended Spectrum β-Lactamase (ESBL) producing Enterobacteriaceae in environmental waters.…”