Polyclonal emergence of vanA vancomycin-resistant Enterococcus faecium in Australia

Area of Science:

• Microbiology
• Genomics
• Epidemiology

Background:

• Vancomycin-resistant Enterococcus (VRE) is a significant healthcare-associated pathogen.
• The emergence of vanA VRE in Australia presented a new public health challenge.

Purpose of the Study:

• To investigate the genetic factors contributing to the emergence of vanA VRE in Australia.
• To understand the molecular epidemiology of vanA VRE in Australian hospitals.

Main Methods:

• Whole-genome sequencing of 18 vanA-positive Enterococcus faecium patient isolates from 2011-2013.
• In silico analysis including typing, transposon, and plasmid assembly.

Main Results:

• Sequenced isolates represented diverse hospital-adapted sequence types (STs).
• Various Tn1546 variants and plasmid backbones were associated with vanA VRE.
• The emergence was polyclonal, not linked to a single dominant ST or plasmid.

Conclusions:

• The emergence of vanA VRE in Australia was polyclonal, indicating diverse genetic origins.
• No single dominant sequence type or vanA-encoding plasmid was identified.
• Potential community sources warrant investigation to fully understand the epidemiological changes.