Vancomycin-Resistant Enterococci

Last Editorial Review: 3/9/2009

Vancomycin-Resistant Enterococci (VRE) Overview

Enterococci bacteria grabbed the attention of public health officials in the 1980s because of its ability to survive in humans and animals, and its knack for sharing those survival tricks with other bacteria.

While enterococci are not as familiar as staphylococcus (staph) or Escherichia coli (E. coli) bacteria, enterococci infections are among the most common type acquired by hospitalized patients. Enterococci, in general, are much less capable of causing disease than staph or E. coli but still can complicate and prolong hospital stays. Virtually the only people who develop illness from Enterococcus are those who are already ill, such as individuals in a hospital intensive-care unit or those who are elderly, have diabetes, have chronic kidney failure, and so forth. So, unlike other forms of resistant bacteria, there is little chance or concern among physicians of Enterococcus becoming epidemic in healthy populations.

But enterococci are of great interest because, as with many of its bacterial counterparts, it can resist and evade several forms of antibiotic therapy, including vancomycin, the antibiotic of last resort for resistant infections.

Enterococcal infections that result in human disease can be fatal, particularly those caused by strains of vancomycin-resistant enterococci (VRE). During 2004, VRE caused about one of every three infections in hospital intensive-care units, according to the Centers for Disease Control and Prevention (CDC).

In 1984, enterococci was given its own genus identity. In 1986, the first VRE strains appeared in Europe and, in 1989, the first case of VRE was reported in the United States. Between 1989 and 1993, the percentage of enterococcal tests that were positive for VRE in the United States rose from 0.3 percent to 7.9 percent.

Researchers seek to develop improved therapeutics as well as gain a better understanding of VRE's genetic survival characteristics and how those resistance genes are passed to other pathogens.

Why is the latter element important? As of 2007, the United States had reported seven cases of vancomycin-resistant Staphylococcus aureus (VRSA) infection, a serious development that has healthcare providers fearful of losing ground in their attempt to control the spread of S. aureus. In one of the cases, scientists confirmed the transfer of a key antibiotic resistance gene from Enterococcus to Staphylococcus.

VRE Risks

Enterococci can survive for months. It primarily resides in the human digestive system and the female genital tract; the enterococci make up a significant part of the normal bacterial population of these sites in healthy people.

However, colonization can progress to infection, particularly for people with certain risk factors. The infection can lead to diseases of the urinary tract, bloodstream, heart valves (endocarditis), and brain (meningitis), as well as to serious infections in open wounds.

Some of the risks for acquiring VRE infection are

  • Persons who have been previously treated with vancomycin and combinations of other antibiotics, such as penicillin and gentamicin

  • Persons who are hospitalized, particularly when they receive antibiotic treatment for long periods of time

  • Persons with weakened immune systems, such as patients in intensive-care units, cancer, or transplant wards

  • Persons who have undergone surgical procedures, such as abdominal or chest surgery

  • Persons with medical devices that stay in for some time, such as urinary catheters or central intravenous catheters

Enterococcal infections are more common in elderly people, particularly those in long-term care facilities and skilled nursing homes because they are more likely to experience infection risk factors, such as exposure to medical instruments.


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Vancomycin-Resistant Enterococci (VRE) Transmission

VRE is transmitted from person to person most commonly by healthcare workers whose hands have inadvertently become contaminated, either from feces, urine, or blood of a person carrying the organism. It can also be spread indirectly via hand contact with open wounds or by touching contaminated environmental surfaces, where the bacterium can survive for weeks. VRE is not transmitted through the air.

Of more than a dozen forms of enterococci bacteria, two are the primary concern for human disease: E. faecium and E. faecalis. E. faecium is the most frequent species of VRE found in hospitals.

Vancomycin-Resistant Enterococci (VRE) Diagnosis

Enterococci have two types of resistance to vancomycin: acquired and intrinsic (natural). Some types of enterococci bacteria acquire the resistance when other bacteria come in contact with enterococci and share genetic information - scientists believe enterococci acquired the gene that resists vancomycin from bacteria in the digestive tract. Acquired resistance has been noted with two clinically important forms of enterococci: E. faecium and E. faecalis.

Of the dozen or so types of enterococci bacteria, some, such as E. gallinarum and E. casseliflavus, have an inherent, low-level resistance to vancomycin. These are very uncommon strains, however, and are of limited clinical significance.

If you have an enterococcal infection, it is crucial that your healthcare providers quickly identify the strain, so that they can determine how best to treat you and prevent patient-to-patient transmission. They will want to know if the strain infecting you is resistant to vancomycin, and if so, is the resistance intrinsic or acquired? If the resistance is acquired, does the strain contain specific genes that can share resistance traits with other bacteria, thus making it able to spread disease?

Tests are available to make those diagnoses.

Some healthcare practitioners, as part of their normal infection control procedures, will test you for the presence of VRE to learn whether you might be infected or colonized with the bacterium. This helps facilities know whether specific procedures should be used to reduce the potential spread of VRE.

Vancomycin-Resistant Enterococci (VRE) Treatment

Most VRE infections can be treated with antibiotics other than vancomycin. Some of the antibiotics that fail to work because of intrinsic resistance include some types of penicillin, cephalosporins, clindamycin, and aminoglycosides. Treatments that are ineffective because of acquired resistance include vancomycin, some penicillins, macrolides (such as erythromycin), tetracycline, quinolones, and others.

The course of treatment is determined by testing different antibiotics in the laboratory to determine which ones might be most effective against the infectious strain. If you develop a VRE infection and have a urinary catheter, sometimes removing the catheter will clear the infection.

If you are colonized with VRE -- the bacteria are present but have not caused an infection -- you usually will not require treatment.

Vancomycin-Resistant Enterococci (VRE) Prevention

Proper hand hygiene - thorough washing with soap and then drying - is the best way to prevent the spread of enterococci.

The CDC Hospital Infection Control Program encourages hospitals to develop their own institution-specific plans, which should stress:

  • Prudent vancomycin use by clinicians

  • Hospital staff education regarding vancomycin resistance

  • Early detection and prompt reporting of vancomycin resistance in enterococci and other gram-positive microorganisms by the hospital microbiology laboratory

  • Immediate implementation of appropriate infection control measures to prevent person-to-person VRE transmission


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Vancomycin-Resistant Enterococci (VRE) Research

The National Institute of Allergy and Infectious Diseases (NIAID) funds laboratory research and clinical trials to address the problem of antimicrobial resistance. NIAID-funded research aims to develop better diagnostics, treatments, and new vaccines that are effective against emerging infectious agents, such as VRE.

NIAID grantees are studying the problem of antibiotic resistance among common bacteria responsible for VRE infections. These projects include:

  • Efforts to develop new vancomycin-based therapeutics to combat VRE and possibly other bacterial infections

  • Studying the spread of E. faecalis to determine how the bacterium shares and acquires genes that alter its characteristics Similar studies funded by other components of the National Institutes of Health are under way at various U.S. medical institutions.

Vancomycin-Resistant Enterococci (VRE) Frequently Asked Questions

How can I prevent the spread of VRE?

If you or someone in your home has VRE, here are some helpful measures that can help prevent its spread:

  • Always wash your hands thoroughly after using the bathroom and before preparing food. Clean your hands after close contact with persons who have VRE. Wash with soap and water (particularly when visibly soiled), or clean with alcohol-based hand cleaner.

  • Frequently clean areas of your home, such as the bathroom, which may become contaminated with VRE. Use a household disinfectant or a mixture of one-fourth cup bleach and one quart of water to clean areas and surfaces that are touched frequently.

  • Wear gloves if you come in contact with body fluids that may contain VRE, such as stool. Always wash your hands after removing gloves.

  • Be sure to tell any healthcare providers that you have VRE, so that they are aware of your infection.

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What should I do if I think I have VRE?

Talk with your healthcare provider and get medical care.

If a patient in a facility is colonized or infected with VRE, what do their visitors or family members need to know?

In general, healthy people are at low risk of getting infected with VRE. Therefore, casual contact, such as kissing, hugging, and touching, is generally safe. Visitors should wash their hands before leaving an infected person's room. Also, wear disposable gloves if you anticipate contact with body fluids. If excessive contact with body fluids is expected, wear a gown. It is also acceptable for infants and children to have casual contact with these patients.

What precautions should caregivers take when tending to infected persons in their homes?

Outside of healthcare settings, there is little risk of becoming infected with VRE. In the home, the following precautions should be taken:

  • Caregivers should wash their hands with soap and water after physical contact with the infected or colonized person, and before leaving the home.

  • Towels used for drying hands after contact should be used only once.

  • Disposable gloves should be worn if contact with body fluids is expected, and hands should be washed after removing the gloves.

  • Linens should be changed and washed on a routine basis, and if they are soiled.

  • The patient's environment should be cleaned routinely, and when soiled with body fluids.

  • Notify doctors and other healthcare personnel, who provide care for patients, if an individual is colonized or infected with a multidrug-resistant organism.

Success stories are encouraging

An Arkansas hospital in 1998 created a program to wipe out VRE by using strict patient containment procedures and thoroughly educating its employees. Among the most effective precautions is handwashing. Though some staff complained that the program was overly complicated and labor intensive, rates of VRE infection dramatically declined.

According to CDC, in late 1996, VRE was first detected in a regional coalition of healthcare facilities -- state and local health departments in Iowa, Nebraska, and South Dakota. Within six months, VRE had spread to nearly half of the healthcare facilities in the region. A VRE Task Force began a mitigation program that combined detecting VRE-colonized or -infected patients, using infection-control measures and appropriate courses of antibiotics. In two years, VRE was significantly reduced throughout the region -- including a marked reduction in long-term care facilities and elimination in all acute-care facilities.

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