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Author(s): J Mourão
Marçal, Sara
Ramos, Paula
Campos, Joana
Machado, Jorge
Luisa Peixe
Novais, Carla
Antunes, Patrícia
Title: Tolerance to multiple metal stressors in emerging non-typhoidal MDR Salmonella serotypes: a relevant role for copper in anaerobic conditions
Issue Date: 2016
Abstract: Objectives: Factors driving the expansion of particular MDR Salmonella serotypes/clones are not completelyunderstood. We assessed if emergent MDR Salmonella serotypes/clones were more enriched in metal tolerance genes (e.g. to Cu/Ag) than other less frequent ones, as an additional feature to survive in environments contaminated with metals.Methods: Metal (Cu pco/Ag,Cu sil/Hg mer/As ars/Te ter) tolerance genes screening (PCR/sequencing), MICs ofCuSO4/AgNO3 (aerobiosis/anaerobiosis), genetic element characterization (S1/I-CeuI PFGE) and conjugation assays were performed in a well-characterized Salmonella collection (n275 isolates; 200014; 49 serotypes/clones).Results: The sil+pco genes were detected in 37% of isolates from diverse serotypes, mainly in emergent Rissen/ST469 and Typhimurium/ST34 European clone (100%), which are mostly associated with pig settings where Cu is highly used. These genes were frequently co-located with merA+terFand/or antibiotic resistance genes in plasmids (100270 kb; IncHI2/IncHI1/IncN/IncFIIA; mostly transferable by conjugation) or in the chromosome. Most sil+pco+ isolates (77%) were MDR contrasting with sil+pco2 ones (48%). The sil+pco+ isolates presented significantly higher MICCuSO4 under anaerobiosis (MIC50/MIC9028/32 mM) and MICAgNO3 after previous Ag contact (MIC50/MIC90.3 mM) than sil2 ones (MIC50/MIC902/8 mM to CuSO4; MIC50/MIC900.125/0.16 mM to AgNO3). Use of these modified methodological approaches allowed the establishment of CuSO4/AgNO3 tolerance cut-offs to differentiate sil+ and sil2 isolates, here firstly proposed.Conclusions: This study demonstrates that acquisition of Cu/Ag tolerance genes (sil/pco genes) might contribute to the emergence of particular clinically relevant MDR Salmonella serotypes/clones by facilitating their survival in diverse metal-contaminated settings, particularly in pig production. Assessment of control measures for the use and/or accumulation of metals in diverse environments are needed to prevent a wider expansion of such strains or the emergence of new ones.
Subject: Ciências da Saúde, Ciências médicas e da saúde
Health sciences, Medical and Health sciences
Scientific areas: Ciências médicas e da saúde
Medical and Health sciences
Document Type: Artigo em Revista Científica Internacional
Rights: restrictedAccess
Appears in Collections:FCNAUP - Artigo em Revista Científica Internacional
FFUP - Artigo em Revista Científica Internacional

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