Tolerance to multiple metal stressors in emerging non-typhoidal MDR Salmonella serotypes: a relevant role for copper in anaerobic conditions

Objectives: Factors driving the expansion of particular MDR Salmonella serotypes/clones are not completely understood. 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 surviv...

Full description

Bibliographic Details
Main Author: J Mourão (author)
Other Authors: Marçal, Sara (author), Ramos, Paula (author), Campos, Joana (author), Machado, Jorge (author), Luisa Peixe (author), Novais, Carla (author), Antunes, Patrícia (author)
Format: article
Language:eng
Published: 2016
Subjects:
Ciências da Saúde, Ciências médicas e da saúde
Health sciences, Medical and Health sciences
Online Access:https://hdl.handle.net/10216/86608
Country:Portugal
Oai:oai:repositorio-aberto.up.pt:10216/86608
Description
Summary:Objectives: Factors driving the expansion of particular MDR Salmonella serotypes/clones are not completely understood. 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 of CuSO4/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.

Similar Items