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Various mobile genetic elements carrying optrA in Enterococcus faecium and Enterococcus faecalis isolates from swine
Huiyong Xuan1,2, Lining Xia2, Stefan Schwarz3,4
1Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China.
The Journal of Antimicrobial Chemotherapy
|December 12, 2022
Summary
The oxazolidinone/phenicol resistance gene optrA was found in unrelated enterococcal isolates from a swine farm. Mobile genetic elements like plasmids and transposons facilitated optrA gene spread within the farm environment.
Area of Science:
- Veterinary Microbiology
- Antimicrobial Resistance
- Genomics
Background:
- Antimicrobial resistance genes pose a significant threat to animal and human health.
- The oxazolidinone/phenicol resistance gene optrA is a critical determinant of resistance to important antibiotics.
- Understanding the dissemination of resistance genes in livestock is crucial for effective control strategies.
Purpose of the Study:
- To investigate the distribution of the optrA gene in enterococci from a swine farm.
- To identify the mobile genetic elements responsible for the spread of optrA.
- To analyze the genetic context of optrA in Enterococcus faecium and Enterococcus faecalis.
Main Methods:
- Isolation and identification of Enterococcus faecium and Enterococcus faecalis from swine at different production stages.
- Antimicrobial susceptibility testing and Pulsed-Field Gel Electrophoresis (PFGE) of optrA-positive isolates.
- Whole Genome Sequencing (WGS) to determine the genetic environment of the optrA gene.
Main Results:
- The optrA gene was detected in 12.2% of enterococcal isolates, primarily from nursery and finishing pigs.
- optR-positive isolates exhibited diverse genetic profiles, indicating multiple dissemination events.
- optR was found on various mobile genetic elements, including novel plasmids and transposons, in both E. faecium and E. faecalis.
Conclusions:
- The optrA gene is present in genetically distinct enterococcal populations within the same swine farm.
- Horizontal gene transfer mediated by plasmids and transposons is a major mechanism for optrA dissemination in this setting.
- Effective farm biosecurity and antimicrobial stewardship are essential to limit the spread of resistance genes.
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