期刊
INTERNATIONAL JOURNAL OF ANTIMICROBIAL AGENTS
卷 45, 期 6, 页码 610-616出版社
ELSEVIER
DOI: 10.1016/j.ijantimicag.2015.01.013
关键词
Biocides; Copper; Silver; Multidrug resistance; Salmonella enterica Typhimurium; monophasic variant
资金
- European Union [Pest-C/EQB/LA0006/2013]
- Investigacao Jovem da Universidade do Porto/Santander Totta
- Foundation for Science and Technology [SFRH/BD/77518/2011, POPH-QREN]
- Fundação para a Ciência e a Tecnologia [SFRH/BD/77518/2011] Funding Source: FCT
The occurrence of acquired metal tolerance genes in emerging MDR Salmonella enterica serotype 4,[5],12:i:- clones was assessed and their associated platforms and tolerance phenotype were characterised. Salmonella 4,[5],12:i:- from different sources belonging to European, Spanish and Southern European clones were studied. Screening for copper (pcoA-pcoD/tcrB), silver/copper (silA-silE), mercury (merA), arsenic (arsB) and tellurite (terF) tolerance genes was performed by PCR/sequencing. CuSO4/AgNO3 MICs were determined in aerobic/anaerobic atmospheres by agar dilution. Conjugation assays, genomic location and plasmid analysis were performed by standard procedures. Most isolates from European (98%) and Spanish (74%) clones carried silA-silE, contrasting with the Southern European clone (26%). merA/62% (European and Spanish clones) and pcoA-pcoD/50% (European clone) were also detected. merA +/- pco + sil were chromosomally located in the European clone, whereas in Spanish and Southern European clones sil merA were within plasmids, both with antibiotic resistance genes. The pcoA-pcoD/silA-silE(+) isolates showed higher MICCuSO4 in anaerobiosis than those without these genes (MIC50 = 24-28 vs. 2 mM). Different MICAgNO3 of silA-silE(+) (MIC50 = 0.25 mM) and silA-silEIMIC(50) = 0.16 mM) isolates were observed in both atmospheres, with an MIC increment after prior exposure to silver (>3 vs. 0.08-0.125 mM) in aerobiosis. A high frequency of copper and silver tolerance, particularly among the two major Salmonella 4,[5],1 2:i: MDR clones (European/Spanish) circulating in Europe and causing human infections, might facilitate adaptation/expansion of these strains in metal-contaminated environments, particularly copper in anaerobiosis. Furthermore, metal toxic concentrations in food-animal environments can contribute to persistence of genetic platforms carrying metal/antibiotic resistance genes in this foodborne zoonotic pathogen. (C) 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.
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