Molecular and Genomic Insights of <i>mcr-1</i>-Producing <i>Escherichia coli</i> Isolates from Piglets
The use of colistin in food-producing animals favors the emergence and spread of colistin-resistant strains. Here, we investigated the occurrence and molecular mechanisms of colistin resistance among <i>E. coli</i> isolates from a Mexican piglet farm. A collection of 175 cephalosporin-re...
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| Main Authors: | , , , , , , , , , |
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| Format: | Book |
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MDPI AG,
2022-01-01T00:00:00Z.
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| Summary: | The use of colistin in food-producing animals favors the emergence and spread of colistin-resistant strains. Here, we investigated the occurrence and molecular mechanisms of colistin resistance among <i>E. coli</i> isolates from a Mexican piglet farm. A collection of 175 cephalosporin-resistant colonies from swine fecal samples were recovered. The colistin resistance phenotype was identified by rapid polymyxin test and the <i>mcr</i>-type genes were screened by PCR. We assessed the colistin-resistant strains by antimicrobial susceptibility test, pulse-field gel electrophoresis, plasmid profile, and mating experiments. Whole-Genome Sequencing data was used to explore the resistome, virulome, and mobilome of colistin-resistant strains. A total of four colistin-resistant <i>E. coli</i> were identified from the cefotaxime-resistant colonies. All harbored the plasmid-borne <i>mcr-1</i> gene, which was located on conjugative 170-kb IncHI-2 plasmid co-carrying ESBLs genes. Thus, high antimicrobial resistance rates were observed for several antibiotic families. In the RC2-007 strain, the <i>mcr-1</i> gene was located as part of a prophage carried on non-conjugative 100-kb-plasmid, which upon being transformed into <i>K. variicola</i> strain increased the polymyxin resistance 2-fold. The genomic analysis showed a broad resistome and virulome. Our findings suggest that colistin resistance followed independent acquisition pathways as clonal and non-genetically related <i>mcr-1</i>-harboring strains were identified. These <i>E. coli</i> isolates represent a reservoir of antibiotic resistance and virulence genes in animals for human consumption which could be potentially propagated into other interfaces. |
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| Item Description: | 10.3390/antibiotics11020157 2079-6382 |