Abstract
The mcr-1 (mobile colistin resistance 1) gene, which encodes phosphoethanolamine transferase, has been recently identified as a source of acquired resistance to polymyxins in Escherichia coli. Using the SuperPolymyxin selective medium, we prospectively screened 100 pigs at 2 farms in Portugal for polymyxin-resistant Enterobacteriaceae and recovered 98 plasmid-mediated MCR-1-producing isolates. Most isolates corresponded to nonclonally related E. coli belonging to many sequence types; we also found 2 Klebsiella pneumoniae sequence types. The mcr-1 gene was carried on IncHI2 or IncP plasmid backbones. Our finding of a high rate of MCR-1 producers on 2 pig farms in Portugal highlights the diffusion of that colistin-resistance determinant at the farm level. The fact that the pigs received colistin as metaphylaxis in their feed during the 6 weeks before sampling suggests selective pressure.
Keywords:
Escherichia coli; Klebsiella pneumonia; MCR-1; Portugal; antimicrobial resistance; bacteria; colistin; mcr-1 gene; pigs.
MeSH terms
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Animals
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Anti-Bacterial Agents / pharmacology
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Colistin / pharmacology
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Conjugation, Genetic
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Escherichia coli / drug effects
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Escherichia coli / genetics*
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Escherichia coli / isolation & purification
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Escherichia coli / metabolism
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Escherichia coli Infections / epidemiology*
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Escherichia coli Infections / microbiology
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Escherichia coli Infections / prevention & control
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Escherichia coli Infections / transmission
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Escherichia coli Proteins / genetics*
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Escherichia coli Proteins / metabolism
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Farms
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Gene Dosage
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Gene Expression
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Gene Transfer, Horizontal*
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Klebsiella Infections / epidemiology*
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Klebsiella Infections / microbiology
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Klebsiella Infections / prevention & control
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Klebsiella Infections / transmission
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Klebsiella pneumoniae / drug effects
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Klebsiella pneumoniae / genetics*
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Klebsiella pneumoniae / isolation & purification
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Klebsiella pneumoniae / metabolism
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Membrane Proteins / genetics*
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Membrane Proteins / metabolism
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Plasmids / chemistry
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Plasmids / metabolism
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Portugal / epidemiology
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Swine
Substances
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Anti-Bacterial Agents
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Escherichia coli Proteins
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MCR-1 protein, E coli
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Membrane Proteins
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mcr-2 protein, E coli
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Colistin