Identification of chromosomal mobile element conferring high-level vancomycin resistance in Enterococcus faecium

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Vancomycin resistance in Enterococcus faecium is a significant public health concern.
• The vanA gene cluster confers high-level vancomycin resistance.
• Understanding the mechanisms of vancomycin resistance gene transfer is crucial for controlling its spread.

Purpose of the Study:

• To investigate the transfer and integration of the vanA gene cluster from a clinical Enterococcus faecium isolate.
• To characterize the mobile genetic element responsible for vancomycin resistance transfer.
• To assess the potential for dissemination of vancomycin resistance.

Main Methods:

• Filter mating experiments to transfer vancomycin resistance.
• Pulsed-field gel electrophoresis and Southern hybridization to analyze DNA.
• Restriction analysis and DNA sequencing to characterize the mobile element.

Main Results:

• Vancomycin resistance was transferred from Enterococcus faecium to Enterococcus faecalis via chromosomal integration.
• A novel mobile element, tentatively named Tn5482, was identified, containing the vanA gene cluster and flanking DNA.
• Tn5482 and similar elements were found in other clinical isolates, suggesting a role in resistance dissemination.

Conclusions:

• Chromosomal integration of vancomycin resistance genes occurs via mobile elements like Tn5482.
• Tn5482 facilitates the spread of vancomycin resistance between enterococcal species.
• These findings highlight the importance of monitoring mobile genetic elements in antimicrobial resistance.