Vancomycin-Resistant Enterococci (VRE) are bacteria that have developed resistance to the antibiotic vancomycin. Enterococci are commonly found in the human intestines and female genital tract without causing illness. VRE is a significant concern primarily within healthcare settings, such as hospitals and long-term care facilities, where it can cause serious infections. Patients with compromised immune systems, those who have undergone surgery, or those treated with antibiotics for extended periods face the highest risk of colonization or infection.
Colonization Versus Active Infection Duration
The presence of VRE in the body is categorized as either colonization or active infection. Colonization occurs when VRE is present, most commonly in the gastrointestinal tract, but is not causing symptoms or illness. An active infection means the bacteria is multiplying and causing a symptomatic disease, such as a urinary tract or bloodstream infection.
The duration of VRE colonization can be lengthy, often lasting for months or even years. The median time for a colonized patient to clear the bacteria is estimated at approximately 26 weeks after initial detection. However, individuals with serious underlying health conditions or prolonged hospital stays have been positive for VRE for as long as 46.5 months. These long-term carriers remain a potential source of transmission in healthcare environments.
The timeline for an active VRE infection is tied directly to the duration of medical treatment, typically involving non-vancomycin antibiotics. Treatment for uncomplicated infections, such as those confined to the urinary tract, may be as short as three to seven days. For serious infections, like VRE bacteremia (a bloodstream infection), the standard course of therapy is often 14 days, though longer courses are common for complex cases.
Environmental Survival on Surfaces
The persistence of VRE is a major factor in its ability to spread throughout hospitals and clinics. This resilient bacteria can survive for prolonged periods on inanimate objects and surfaces. Contaminated medical equipment, linens, and hospital room surfaces can thus act as reservoirs for transmission. This capacity for extended environmental persistence underscores why meticulous cleaning and disinfection protocols are necessary in healthcare settings.
VRE can remain viable on dry surfaces for a period ranging from five days to two months. Specific strains have been recovered after four months under dry conditions, and some research suggests viability in environmental samples for over three years. Survival duration varies depending on the type of surface; for example, VRE persists on countertops for five to seven days and on bedrails for at least 24 hours.
The Process of Determining Clearance
Medical professionals determine if a patient has cleared VRE colonization using a specific testing protocol. This procedure relies on obtaining surveillance cultures, typically using a rectal or perirectal swab or a stool specimen, which are tested in a laboratory. The goal is to confirm the absence of VRE bacteria from the body site where it typically colonizes.
The standard for declaring a patient cleared of colonization is achieving three sequential negative cultures. These samples must be collected at least one week apart to ensure a reliable result. Patients should not be receiving antibiotics active against VRE during sample collection, as this could suppress the bacteria and lead to a false-negative result. Because VRE shedding can be intermittent, multiple spaced-out negative tests are necessary to confirm clearance. Even after meeting the three-negative-culture criterion, a small percentage of patients may still experience a recurrence of VRE positivity.