It is acknowledged that the environment facilitates antibiotic resistance development and spread but not much research has been undertaken to understand the mechanisms involved. This study focuses on antibiotic resistance transfer by enterococci, normal inhabitants of the mammalian gut and important healthcare associated pathogens, under a variety of environmental conditions. These are novel environmental strains, isolated from a farm in Monaghan, Ireland. The primary aim of this project is to quantify factors controlling the horizontal gene transfer (HGT) of antibiotic resistance genes via pheromone-induced conjugation. The main objectives include; identifying enterococcal isolates capable of transferring antibiotic resistance genes under laboratory conditions; using whole genome sequencing (WGS) to characterise genetic events involved in conjugal transfer; developing markers of transfer efficiency; and developing environmentally relevant models to measure enterococcal HGT. The transfer of vancomycin resistance genes from a donor to a recipient cell have been demonstrated and transfer efficiencies range from 1.09×10 to 9.74×10. This data shows that some donors are better at donating vancomycin resistance genes than other donors and some recipients are better than other recipients at receiving them. Preliminary data also shows the transfer of trimethoprim, tetracycline and erythromycin and we can see that within a localised environment Enterococcus faecalis can spread resistance genes very differently. In conclusion this project hopes to further our knowledge of the mechanism of pheromone-induced conjugation in environmental Enterococci and to show that environmental enterococcal strains can become multi-drug resistant just as easily as clinical isolates.

  • This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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