Prevention and Control of VRE in ICUs
Although less data were available 14 years ago on the epidemiology and control of VRE,
recommendations of the CDC’s Hospital Infection Control Practices Advisory Committee
(HICPAC) have stood the test of time (164). Virtually all of HICPAC’s recommendations to
prevent and control the spread of VRE have been supported by the studies published in the
last 14 years. Thus, the focus for control and prevention is on the following: (i) detection of
colonized patients by surveillance cultures; (ii) barrier isolation; (iii) hand hygiene; (iv)
environmental decontamination; and (v) control of antimicrobial (particularly vancomycin)
use. The HICPAC guideline also emphasized that prevention and control should start in ICUs
and other areas where the VRE transmission rate is the highest.
Culture Surveillance
Because only about 10% of patients colonized with VRE develop infection, most patients who
make up the reservoir of VRE in the hospital are colonized and not infected. Colonization can
be detected only by surveillance cultures. Colonized patients have been detected by screening
stool specimens submitted to the clinical microbiology laboratory forClostridium difficiletoxin
assay (165). Stool may be collected and sent from the ICU to the clinical microbiology
laboratory, but in most cases perirectal swab specimens are cultured in broth or streaked to
solid agar. One group of authors found that a rectal swab sample had a sensitivity of 58% in
detecting VRE compared with culture of stool (166). These authors also noted that the
concentration of VRE in stool increased with the number of antibiotics administered and
duration of their administration. It is likely that perirectal swab cultures will have a higher
sensitivity for detection of VRE in ICUs where many patients are on antibiotics.
In another study in a burn unit, the authors observed that perirectal swabs had the same
sensitivity for detecting VRE whether inoculated to broth or to solid media (144). This suggests
that small numbers of VRE detected by broth amplification can also be detected by growth on
solid media. This may have been due to the extensive use of antimicrobial agents in the burn
unit where the study was performed. The HICPAC guideline also recommends culturing urine
and wounds for VRE (164). This will likely increase the sensitivity of surveillance cultures.
Surveillance cultures can be made more efficient by using a selective culture media to
suppress growth of other microorganisms that will likely contaminate the specimens (144,164).
It is likely that most patients who are colonized with VRE in an ICU will be detected by
perirectal swabs and swabs of open wounds and other skin sites inoculated to selective media.
This recommendation is further supported by a study that found that rectal and perirectal
swabs had approximately the same sensitivity (79%) (167).
Surveillance cultures and isolation of colonized and infected patients has been shown in
many studies to control VRE in both acute care and long-term care facilities (136,138,139,
149,168–172). One publication describes the effective control of VRE in four acute-care hospitals
and in 26 long-term care facilities in the Siouxland region of Iowa, Nebraska, and South
Dakota (168).
Barrier Precautions
Patients with VRE infections and VRE colonization detected by surveillance cultures should be
immediately placed on contact precautions. The HICPAC guideline recommends placement of
patients in a single room or in the same room as other patients with VRE (164). The guideline
also recommends donning clean nonsterile gloves prior to entering the room. The CDC 2006
MDRO Guideline now recommends that both gloves and gown be donned prior to entering
the room of a patient on contact precautions (100).
There are few data on when patients colonized or infected with VRE may be taken off
isolation. The CDC’s HICPAC recommendation was that isolation be discontinued when three
sets of cultures taken from stool or by rectal swab and all previous positive body sites were
culture negative for VRE on three occasions at least one week apart (164). One study has been
published that supports the recommendation made by HICPAC that patients may be taken off
isolation after three consecutive negative cultures taken at least one week apart (173).
116 Mayhall