Vancomycin-Resistant Enterococcus, Molecular Detection, PCR
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Identifying carriers of vancomycin-resistant enterococci
Real-Time Polymerase Chain Reaction (PCR)
(PCR is utilized pursuant to a license agreement with Roche Molecular Systems, Inc.)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
VRE (vancomycin-resistant enterococcus)
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Specimen Type: Perianal, perirectal, rectal
Container/Tube: Culture transport swab
Specimen Volume: Swab
Additional Information: Specimen source is required.
Forms: If not ordering electronically, submit a Microbiology Request Form (Supply T244) with the specimen.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
E-swab, calcium alginate swab, cotton-tipped swab, swab sent in gel transport medium, swab sent in viral or universal transport medium, frozen swab
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
|Varies||Refrigerated (preferred)||7 days|
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Vancomycin-resistant enterococci (VRE) are major nosocomial pathogens. Patients who are particularly vulnerable to fatal disease from VRE include those with hematologic malignancies and liver transplants. Nosocomial spread of VRE occurs as the result of fecal carriage. Risks for both colonization and infection include prolonged hospitalization, intensive care unit stay, transplantation, hematologic malignancies, and prolonged exposure to antibiotics.
The Centers for Disease Control and Prevention provides recommendations to prevent the spread of VRE in institutional settings. These recommendations include isolation of patients experiencing active VRE infection, screening of patients by perianal swab or fecal testing to identify carriers of VRE, and subsequent isolation or cohorting of VRE carriers. Identification and isolation of VRE carriers has been shown to be cost-effective.
In Enterococcus faecalis or Enterococcus faecium, vancomycin resistance is usually associated with the presence of the vanA or vanB genes. The presence of these genes is detected by a molecular method in this assay.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Positive test results indicate the presence of either the vanA or vanB gene, which confers vancomycin resistance in Enterococcus faecalis and Enterococcus faecium (and occasionally other organisms). Patients with a positive test result should be placed in isolation or cohorted with other vancomycin-resistant enterococci (VRE) carriers according to the institution's infection control practices.
A negative result indicates the absence of detectable vanA or vanB DNA in the specimen but does not rule out carrier status as false negative results may occur due to inhibition of PCR, sequence variability underlying primers and/or probes, or the presence of VRE in quantities less than the limit of detection of the assay. In the rare event that PCR testing appears to be negative but there is evidence of PCR inhibition, the result will read "PCR inhibition present"; in such a case, a new specimen should be submitted for repeat testing.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
A positive result does not imply the presence of vancomycin-resistant enterococci (VRE) disease; the presence of vanA or vanB genes correlates with colonization by VRE. Colonization with VRE is not associated with any signs or symptoms.
vanA or vanB genes may occasionally be found in organisms other than enterococci.
Perianal swabs (894) were evaluated for the presence of vanA or vanB DNA by the vancomycin-resistant enterococci (VRE) PCR assay and compared to culture using selective and differential media. Compared to culture the VRE PCR assay was 98% sensitive and 98% specific. The VRE PCR assay detected 35 more positive specimens than the culture method. No cross-reactivity was seen when tested on a panel of pathogenic and normal flora bacteria of the gastrointestinal tract. Enterococcus sp containing the vanC gene were not detected with the VRE PCR assay.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Sloan LM, Uhl JR, Vetter EA, et al: Comparison of the Roche LightCycler vanA/vanB detection assay and culture for detection of vancomycin-resistant enterococci from perianal swabs. Submitted J Clin Microbiol 2004;42:2636-2643
2. Vancomycin-resistant enterococci: Colonization, infection, detection, and treatment. (November 2007). In Mayo Clinic, Mayo Medical Laboratories Communique, Vol 32, No. 11
3. Zirakzadeh A, Patel R: Epidemiology and mechanisms of glycopeptide resistance in enterococci. Curr Opin Infect Dis 2005; 18:507-12
4. Zirakzadeh A, Patel R: Vancomycin-resistant enterococci colonization, infection detection and treatment. Mayo Clinic Proc 2006; 81:529-36
5. Patel R: Enterococcal-type glycopeptides resistance genes in non-enterococcal organisms. FEMS Microbiol. Lett. 2000;185:1
Method Description Describes how the test is performed and provides a method-specific reference
Bacterial DNA is extracted from the specimen. Using the LightCycler instrument and fluorescent energy transfer probes, vanA and vanB genes responsible for vancomycin resistance in enterococci are detected directly from perianal swabs or fecal specimens. (Sloan LM, Uhl JR, Vetter EA, et al: Comparison of the Roche LightCycler vanA/vanB detection assay and culture for detection of vancomycin-resistant enterococci from perianal swabs. J Clin Microbiol 2004;42:2636-2643)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
3 days if received in a swab transport
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
|Result ID||Reporting Name||LOINC Code|