Vancomycin Resistant Enterococci (VRE)

Vancomycin Resistant Enterococci (VRE)

The Organism

• Enterococci originated as a separate species in mid-1980’s (prior to availability of nucleic acid studies these organisms were considered part of the Streptococcus species)
• Facultative anaerobic gram positive cocci that inhabit the gastrointestinal tract of human hosts
• More than a dozen Enterococcal species have been isolated to date
• Hearty organisms with the ability to survive in 6.5% NaCl and at a pH of 9.6, to grow at 10 and usually 45 degrees centigrade and are able to survive at 60 degrees centigrade for 30 minutes (1)
• Possess intrinsic mechanisms of resistance and keen ability to acquire resistance extrinsically
• Five types of Vancomycin (glycopeptide) resistance (VanA, VanB, VanC, VanD, and VanE) all externally acquired except for VanC which is a chromosomally encoded characteristic of the species (2)

Epidemiology

• First reported in France and England in 1986 and in the US in 1987
• From late 1980’s to mid 1990’s the rate of VRE isolates increased 34-fold due in large part to intensive care unit hospitalizations (3); increases have also been identified in the general medical/surgical hospitalized population
• At present one quarter of all enterococcal isolates are vancomycin resistant (3)
• Risk factors include host, hospital, and medication related variables (4)

• Treatment for VRE colonization is not recommended.
• VRE infections are often difficult to treat and may require a polypharmacological approach based on anecdotal evidence of in-vitro studies.

• Laboratory based identification of Enterococci: In addition to media appropriate for each body site, specimens are plated to a selective Trypticase Soy Agar plate containing 5% sheep blood, 10 ug/ml vancomycin and 8 ug/ml gentamycin (made at JHH). Positive culture results are available in 48 hours.
  

Infection Control

VRE, as mentioned above, is a hearty organism capable of surviving on environmental surfaces for extended periods of time.

• Gloved and ungloved hands, telephones and stethoscopes (60 minutes)
• Bedrails (up to 24 hours)
• Countertops (6 days)
  

The prudent question is this: Why does VRE live on environmental surfaces for different lengths of time?

Answer: It doesn’t. The difference between the items above is the amount of hand traffic the items receive. Therefore, VRE easily moves from inanimate objects (fomites) to the hands of a HCW or support staff and then possibly to patients.

Both the Johns Hopkins Hospital and the CDC have guidelines for preventing the spread of VRE ( JHH VRE Guidelines) which are summarized below:

• Isolation in a private room with barrier precautions (gown, gloves to enter the room even briefly and appropriate hand hygiene) VRE is listed under Special Precautions at JHH. (5)
• Patient education about the organism and appropriate prevention techniques
• Promoting HAND HYGIENE is the single most effective means of preventing infection
• Compliance with isolation precautions is monitored and feedback provided when breakdowns in practice is noted
• Significant reduction in VRE transmission has been shown simply by following isolation precautions that include gowning and gloving before entering the patient’s room (6)
• Dedicated equipment for patient care is utilized whenever possible (disposable stethoscopes, thermometers, BP cuffs, etc)
• Limited type and amount of supplied entering the room and dispose of all unused items at patient discharge
• Initiate epidemiological and laboratory investigations for increasing rates or identified nosocomial transmission

• Educate healthcare workers and support personnel on appropriate isolation techniques
• Educate housekeeping staff regarding the importance of a thorough environmental cleaning of all isolation rooms daily
• HAND HYGIENE is the single most effective means of preventing infection (so important we said it twice)
• Surveillance cultures should be routinely conducted through the institution to identify colonization and facilitate isolation practices
• Antibiotic management
• Vancomycin use should be limited to situations in which it is absolutely indicated and guidelines have been published by the Hospital Infection Control Practices Advisory Committee (8)
  

Examples of situations when vancomycin is NOT recommended:

• Routine prophylaxis for surgical patients without allergy to beta lactam antibiotics, low birth-weight infants, dialysis patients, patients with neutropenia, patients with central venous catheters.

References

1. Murray, B.E. (1990). The life and times of enterococcus. Clinical Microbiology Reviews, 3, 46-65.
   
   
2. Wood, A.J. (2000). Vancomycin resistant enterococcal infections. New England Journal of Medicine, 342, 710-721.
   
   
3. Centers for Disease Control and Prevention (CDC) NNIS System. National Nosocomial Infection Surveillance (NNIS) system report, 2000. American Journal of Infection Control, 28, 429-448.
   
   
4. Perl, T. Delisle, S. (1998). The Emergence and control of vancomycin resistant Enterococci. Grand Rounds in Infectious Diseases, Scientific Exchange, Inc.
   
   
5. Noskins, G.A. (1995) Recovery of vancomycin-resistant enterococci on fingertips and environmental surfaces. Infection Control Hospital Epidemiology, 16, 577-581.
   
   
6. Srinivasin, A. et al (2000). Gowns and glove precautions versus gloves alone in preventing transmission of vancomycin-resistant enterococci in an ICU. Abstract # 390; Presented at Infectious Disease Society of America (IDSA), New Orleans, Louisiana.
   
   
7. Recommendations for preventing the spread of vancomycin resistance: recommendations of the Hospital Infection Control Practices Advisory Committee (HICPAC) Centers for Disease Control and Prevention. MMWR (1995); 44 (RR-12):1-13.

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