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Genetic characterization of MDR genomic elements carrying two aac(6')-aph(2″) genes in feline-derived clinical
Xue-Song Li1,2, Yu Qi1,2, Peng-Hui Li1,2
1Department of Veterinary Medicine, College of Animal Science and Technology, Jilin Agricultural University, Changchun, China.
Abstract:
Multidrug-resistant Enterococcus faecalis (E. faecalis) often cause intestinal infections in cats. The aim of this study was to investigate a multidrug-resistant E. faecalis isolate for plasmidic and chromosomal antimicrobial resistance and their genetic environment. E. faecalis strain ESC1 was obtained from the feces of a cat. Antimicrobial susceptibility testing was carried out using the broth microdilution method. Conjugation experiments were performed using Escherichia coli and Staphylococcus aureus as receptors. Complete sequences of chromosomal DNA and plasmids were generated by whole genome sequencing (WGS) and bioinformatics analysis for the presence of drug resistance genes and mobile elements. Multidrug-resistant E. faecalis ESC1 contained a chromosome and three plasmids. The amino acid at position 80 of the parC gene on the chromosome was mutated from serine to isoleucine, and hence the amino acid mutation at this site led to the resistance of ESC1 strain to fluoroquinolones. Eleven antibiotic resistance genes were located on two plasmids. We identified a novel composite transposon carrying two aminoglycoside resistance genes aac(6')-aph(2″). This study reported the coexistence of a novel 5.4 kb composite transposon and a resistance plasmid with multiple homologous recombination in an isolate of E. faecalis ESC1. This data provides a basis for understanding the genomic signature and antimicrobial resistance mechanisms of this pathogen.
Insights
Multidrug-resistant Enterococcus faecalis strains in cats harbor both chromosomal and plasmid-mediated resistance genes. Whole genome sequencing revealed a novel transposon and recombination events contributing to antimicrobial resistance mechanisms.
Area of Science:
- Veterinary Microbiology
- Genomics
- Antimicrobial Resistance
Background:
- Multidrug-resistant Enterococcus faecalis (E. faecalis) are significant causes of intestinal infections in felines.
- Understanding the genetic basis of resistance is crucial for effective treatment and control.
Purpose of the Study:
- To investigate the plasmidic and chromosomal antimicrobial resistance mechanisms in a multidrug-resistant E. faecalis isolate from a cat.
- To analyze the genetic environment of these resistance determinants.
Main Methods:
- Whole genome sequencing (WGS) of E. faecalis strain ESC1.
- Antimicrobial susceptibility testing (broth microdilution).
- Conjugation experiments and bioinformatics analysis for resistance genes and mobile elements.
Main Results:
- The E. faecalis ESC1 strain exhibited resistance to fluoroquinolones due to a specific mutation in the parC gene.
- Eleven antibiotic resistance genes were identified on two plasmids.
- A novel composite transposon carrying aminoglycoside resistance genes (aac(6')-aph(2")) was discovered.
Conclusions:
- The study elucidated the genomic basis of multidrug resistance in a feline E. faecalis isolate.
- Identified a novel composite transposon and plasmid-mediated resistance, highlighting complex recombination events.
- Provides insights into antimicrobial resistance mechanisms in veterinary pathogens.
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