Vancomycin-Resistant Enterococci (VRE) are bacteria that have developed resistance to the antibiotic vancomycin, posing a significant concern in healthcare settings. VRE can lead to challenging infections, especially for vulnerable individuals. This article explains VRE, the purpose and process of VRE cultures, how results are interpreted, and strategies for prevention and management.
Understanding VRE
Enterococci are common bacteria found naturally in the human digestive tract and, in women, also in the female genital tract. While usually harmless there, certain strains can cause infections if they spread to other body parts. VRE is a strain of Enterococci that has acquired resistance to vancomycin, an antibiotic used for serious bacterial infections.
Antibiotic resistance develops when bacteria are exposed to antibiotics, allowing resistant strains to survive and multiply. Overuse or misuse of antibiotics can accelerate this process. VRE is most frequently encountered in hospitals and other healthcare facilities, such as nursing homes. Patients at higher risk of acquiring VRE include those hospitalized for extended periods, with weakened immune systems, with indwelling medical devices like catheters, or who have received multiple courses of antibiotics.
Purpose of VRE Culture
VRE cultures determine if an individual is colonized with or infected by these resistant bacteria. Colonization means the bacteria are present on or in the body without causing symptoms or illness. An infection, conversely, means the bacteria are actively causing disease and symptoms.
Healthcare facilities often conduct VRE cultures for surveillance, especially in high-risk units like intensive care units (ICUs), to monitor and prevent VRE spread. Cultures may be ordered for patients upon hospital admission, particularly if they have a history of VRE or transfer from another healthcare facility. They are also performed before certain medical procedures or if a patient develops signs or symptoms suggesting an infection, helping clinicians guide appropriate treatment and infection control measures.
The VRE Culture Process
Collecting a sample is the first step in performing a VRE culture. The type of sample varies depending on the suspected site of colonization or infection. Common samples include rectal swabs or stool samples for detecting VRE in the digestive tract. For suspected infections, samples like wound swabs, urine, or blood may be collected.
Once collected, the sample is sent to a laboratory for processing. In the lab, the sample is cultured on a specialized growth medium designed to promote Enterococci growth while suppressing other bacteria. This medium contains vancomycin, which selectively grows only vancomycin-resistant strains. After incubation (1 to 4 days), the lab examines the culture for bacterial growth. If growth is observed, further tests confirm the presence of Enterococci and verify their resistance to vancomycin.
Interpreting Culture Results
Interpreting VRE culture results involves understanding the difference between a positive and a negative outcome. A negative VRE culture result indicates that vancomycin-resistant Enterococci were not detected in the collected sample. This suggests the individual is not colonized or infected with VRE at the time of testing.
Conversely, a positive VRE culture result means vancomycin-resistant Enterococci were identified in the sample. A positive result does not always signify an active infection; it can indicate colonization, meaning the bacteria are present without causing illness. The distinction between colonization and infection is determined by the patient’s symptoms and clinical presentation, guiding appropriate medical responses and infection control practices.
Living with VRE and Prevention
A positive VRE culture result, whether indicating colonization or infection, has implications for patient care and public health. If a person is colonized with VRE but has no symptoms, antibiotic treatment is not recommended. Healthcare providers will implement specific infection control precautions to prevent VRE spread to other vulnerable individuals. These measures include strict hand hygiene, using gloves and gowns when caring for the patient, and ensuring thorough environmental cleaning of the patient’s surroundings.
For individuals with an active VRE infection, treatment involves using other antibiotics to which the VRE strain is susceptible. The choice of antibiotic depends on the specific VRE strain and the site of infection. Broader prevention strategies for the general public emphasize proper antibiotic use, avoiding unnecessary prescriptions, and completing full courses of treatment. Consistent hand hygiene, especially in healthcare settings and after using the restroom, is a key practice to limit the spread of VRE and other healthcare-associated infections.