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Vancomycin/Glycopeptide-resistant Enterococci (VRE/GRE)

The word ‘Enterococcus’ originates from the Greek word enteron, meaning ‘the gut or intestine’, and kokkos meaning ‘a berry’. They are present mainly in the gastrointestinal tract but also found in the anterior urethra, vagina, skin, and oropharynx of healthy individuals. They are commensal bacteria with low virulence.

Vancomycin-resistant Enterococci (VRE) are sometimes called Glycopeptide-resistant Enterococci (GRE) as they are resistant to the glycopeptide group (i.e. vancomycin, teicoplanin, ramoplanin, oritavancin, dalbavancin, and telavancin).

The most common species that cause infection in humans are E. faecalis (~ 90%), but the incidence of infections is rising. E. faecium. E. faecium is intrinsically more antibiotic-resistant than E. faecalis, and compared to E. faecalis (1%), E. faecium is more often resistant to vancomycin, making it more difficult to treat.

However, they are now recognised as human pathogens and a leading cause of healthcare-associated infections. Infections occur in high-risk groups, including patients with a history of antibiotic use (particularly vancomycin), the presence of an invasive medical device and being immunocompromised.

Risk factors for GRE colonisation and infection include:

  • Prior use of multiple courses of antibiotics
  • Colonisation pressure, i.e. the proportion of VRE/GRE-positive patients in a unit
  • Exposure to other colonised or infected patients, contaminated items, equipment, and environmental surfaces with VRE/GRE
  • Presence of invasive devices, chronic skin ulcers, and severity of illness
  • Admission to an intensive care unit, and
  • Prolonged stay in healthcare facilities where VRE/GRE is endemic.


Most enterococcal infections have been attributed to endogenous sources. However, in an outbreak situation or when the organism is endemic in a healthcare facility, patient-to-patient transmission can occur through direct or indirect contact via the hands of personnel and/or from contaminated patient-care items (especially rectal thermometers), equipment, and environmental surfaces.

References and Further Reading

  • O’Driscoll T, Crank CW.Vancomycin-resistant enterococcal infections: epidemiology, clinical manifestations, and optimal management. Infect Drug Resist2015; 8:217–30.
  • Best Practices for Infection Prevention and Control of Resistant Staphylococcus aureus and Enterococci in all healthcare settings. Ontario: Provincial Infectious Diseases Advisory Committee, 2012.

Reyes K, Bardossy AC, Zervos M. Vancomycin-resistant Enterococci epidemiology, infection prevention, and control. Infect Dis Clin N Am 2016; 30:953–65.