Vancomycin resistance is encoded on a pheromone response plasmid in Enterococcus faecium 228

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Enterococcus faecium is a significant cause of hospital-acquired infections.
• Vancomycin resistance in enterococci is a growing public health concern.
• Conjugative plasmids play a crucial role in the dissemination of antibiotic resistance genes.

Purpose of the Study:

• To characterize the genetic basis of vancomycin resistance in Enterococcus faecium 228.
• To investigate the transferability and functional properties of the vancomycin resistance plasmid.
• To identify novel plasmid-mediated traits beyond antibiotic resistance.

Main Methods:

• Plasmid isolation and characterization (55-kilobase plasmid pHKK100 identified).
• Conjugative transfer experiments into susceptible Enterococcus faecalis strains.
• Assessment of pheromone response capabilities conferred by the plasmid.

Main Results:

• The vancomycin resistance determinant in E. faecium 228 resides on the conjugative plasmid pHKK100.
• pHKK100 was efficiently transferred to susceptible E. faecalis strains.
• Transconjugants acquired the ability to respond to pheromones produced by E. faecalis and Streptococcus sanguis.

Conclusions:

• pHKK100 is the first described plasmid mediating both vancomycin resistance and bacterial pheromone response.
• This dual functionality highlights the complex roles plasmids can play in bacterial adaptation and interspecies communication.
• Understanding such plasmids is critical for combating antibiotic resistance and its spread.