Assessing pure isolates of gram-negative bacilli for mechanism of carbapenem resistance
This is a rapid molecular test that detects OXA-48-like beta-lactamase and VIM metallo-beta-lactamase DNA associated with antimicrobial resistance in isolates of gram-negative bacilli.
Real-Time Polymerase Chain Reaction (PCR) using LightCycler and Fluorescent Resonance Energy Transfer (FRET)
Carbapenem resistant Enterobacteriaceae
Carbapenem resistant CRE
Carbapenemase producing, carbapenem resistant Enterobacteriaceae
Carbapenemase
CP-CRE
Oxacillinase
OXA
OXA-48
OXA-48-like
VIM
CRE
Varies
This assay should be used for testing of isolates of gram-negative bacilli. If testing directly from rectal swabs, perirectal swabs, anal swabs, perianal swabs, or stool is desired, order OVSRP / Oxacillin-Hydrolyzing Beta-Lactamase (blaOXA-48-like) and Verona Integron-Encoded Metallo-Beta-Lactamase (blaVIM) DNA Surveillance, PCR, Varies
Other mechanisms of carbapenem resistance, including other carbapenemase-types, porin mutations, or hyperexpression of drug efflux pumps may result in carbapenem resistance. These are not detected by this assay. If testing for Klebsiella pneumoniae carbapenemase (KPC) or New Delhi metallo-beta-lactamase (NDM) is desired, order KPNRP / KPC (blaKPC) and NDM (blaNDM) in Gram-Negative Bacilli, Molecular Detection, PCR.
1. Organism identification must be provided. If organism identification is unknown, concomitantly order IDENT / Organism Referred for Identification, Aerobic Bacteria.
2. If susceptibility testing is needed; also order ZMMLS / Antimicrobial Susceptibility, Aerobic Bacteria, Varies.
3. If testing for Klebsiella pneumoniae carbapenemase or New Delhi metallo-beta-lactamase is also needed; also order KPNRP / KPC (blaKPC) and NDM (blaNDM) in Gram-Negative Bacilli, Molecular Detection, PCR.
1. For shipping information see Infectious Specimen Shipping Guidelines .
2. Place specimen in a large infectious container and label as an etiologic agent/infectious substance, if appropriate.
Organism identification and specimen source are required.
Question ID | Description | Answers |
---|---|---|
OXORG | Organism Identified by Client | |
OXSRC | Specimen Source |
The high sensitivity of amplification by polymerase chain reaction requires the specimen to be processed in an environment in which contamination of the specimen by oxacillin-hydrolyzing beta-lactamase (OXA-48-like) or Verona integron-encoded metallo-beta-lactamase (VIM) DNA is unlikely.
Supplies: Infectious Container, Large (T146)
Container/Tube: Slant
Specimen Volume: Isolate
Collection Instructions:
1. Perform isolation of infecting bacteria.
2. Bacterial organism must be submitted in pure culture, actively growing. Do not submit mixed cultures.
If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.
Agar plate Mixed culture | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Varies | Ambient (preferred) | ||
Refrigerated |
Assessing pure isolates of gram-negative bacilli for mechanism of carbapenem resistance
In the United States, Klebsiella pneumoniae carbapenemase (KPC) is the most common carbapenemase, followed by New Delhi metallo-beta-lactamase (NDM). OXA-48-like (oxacillin-hydrolyzing beta-lactamase) and VIM (Verona integron-encoded metallo-beta-lactamase) carbapenemases predominate in other parts of the world but are also seen in the United States. The genes blaOXA-48-like and blaVIM encode OXA-48-like and VIM enzyme production, respectively. Polymerase chain reaction is a sensitive, specific, and rapid means of identifying these genes. This test detects the genes encoding OXA-48-like and VIM types of beta-lactamases in bacterial isolates.
Not applicable
This polymerase chain reaction (PCR) detects and differentiates blaOXA-48-like and blaVIM. A positive blaOXA-48-like (oxacillin-hydrolyzing beta-lactamase) PCR result indicates that the isolate carries blaOXA-48-like. A positive VIM (Verona integron-encoded metallo-beta-lactamase) PCR result indicates the isolate carries blaVIM. A negative result indicates the absence of detectable DNA.
False-negative results may occur due to inhibition of polymerase chain reaction, sequence variability underlying primers and probes, or the presence of the blaOXA-48-like or blaVIM genes in quantities lower than the limit of detection of the assay.
The assay was validated using 46 gram-negative bacilli, including 30 carbapenemase-producers (26 OXA/VIM-type, 1 NMC/IMI, 1 NDM-1, and 2 KPC) and 2 gram-positive organisms. The assay provided 100% sensitivity and specificity for both targets.
1. Bush K, Fisher JF: Epidemiological expansion, structural studies, and clinical challenges of new beta-lactamases from gram-negative bacteria. Annu Rev Microbiol. 2011;65:455-478
2. Poirel L, Potron A, Nordmann P: OXA-48-like carbapenemases: the phantom menace. J Antimicrob Chemother. 2012 Jul;67(7):1597-1606
3. Nordmann P, Naas T, Poirel L: Global spread of carbapenemase-producing Enterobacteriaceae. Emerg Infect Dis. 2011 Oct;17(10):1791-1798
Isolates are lysed in buffer to release their DNA. This assay amplifies and detects a specific portion of the genes encoding the OXA-48-like (oxacillin-hydrolyzing beta-lactamase) and VIM (Verona integron-encoded metallo- beta-lactamase) enzymes. The LightCycler instrument amplifies and monitors target nucleic acid sequences by fluorescence during PCR cycling. This is an automated PCR system that can rapidly detect amplified product development through stringent air-controlled temperature cycling and capillary cuvettes. The detection of amplified products is based on the fluorescent-resonance energy transfer (FRET) principle. For FRET product detection, hybridization probes with a donor fluorophore, fluorescein, on the 3' end are excited by an external light source, which emits light that is absorbed by secondary hybridization probes with acceptor fluorophores, LC-Red 610 (blaOXA-48-like) and LC-Red 670 (blaVIM) on the 5' end. The acceptor fluorophore then emits a light of a different wavelength that can be measured with a signal that is proportional to the amount of specific PCR product. The detection process is completed in less than 1 hour using a closed tube system.(Fernandez J, Cunningham SA, Fernandez-Verdugo A, et al: Evaluation of a real-time PCR assay for rectal screening of OXA-48-producing Enterobacteriaceae in a general intensive care unit of an endemic hospital. Diagn Microbiol Infect Dis. 2017 Jul;88(3):252-258. doi: 10.1016/j.diagmicrobio.2017.04.001)
Monday through Friday
This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.
87150 x 2
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
OXVRP | OXA-48 and VIM PCR | 85502-3 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
OXORG | Organism Identified by Client | 43409-2 |
OXSRC | Specimen Source | 31208-2 |
41743 | OXA-48-like PCR | 85503-1 |
41744 | VIM PCR | 85501-5 |