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HelpTest Code CARBI Carbapenem Resistance Genes, Molecular Detection, PCR, Varies
Infectious
Ordering Guidance
This assay should be used for testing of isolates of Enterobacterales, Pseudomonas aeruginosa and Acinetobacter baumannii. If testing directly from rectal swabs is desired, order CRPCR / Carbapenem Resistance Genes, Molecular Detection, PCR, Rectal Swab.
Other mechanisms of carbapenem resistance, including other carbapenemase not targeted by this assay, porin mutations, and hyperexpression of drug efflux pumps, may result in carbapenem resistance. These mechanisms are not detected by this assay.
Additional Testing Requirements
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.
Shipping Instructions
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.
Necessary Information
Organism identification and specimen source are required.
Specimen Required
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 Klebsiella pneumoniae carbapenemase (KPC), New Delhi metallo-beta-lactamase (NDM), Verona integron-encoded metallo-beta-lactamase (VIM), oxacillin-hydrolyzing beta-lactamase (OXA-48), and imipenemase-type metallo-beta-lactamase (IMP) DNA is not likely.
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.
Useful For
Detecting and differentiating blaKPC, blaNDM, blaVIM, blaOXA-48, and blaIMP gene sequences associated with carbapenem intermediate or resistant results
Aiding in infection control in the detection of gastrointestinal colonization of patients in healthcare settings with bacteria not susceptible to carbapenems using bacterial isolates from rectal or perirectal swabs
Method Name
Real-Time Polymerase Chain Reaction (PCR)/Reverse Transcription (RT-PCR)
Reporting Name
Carbapenem Resistance Genes, VariesSpecimen Type
VariesSpecimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Ambient (preferred) | ||
| Refrigerated | |||
Reject Due To
| Agar plate Mixed culture |
Reject |
Clinical Information
The global spread of carbapenemase-producing Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii (organisms not-susceptible to carbapenem antimicrobials) is a critical public health issue. These bacteria are often resistant to all beta-lactam agents and frequently also resistant to multiple classes of other antimicrobial agents, leaving very few treatment options. Tracing the spread of organisms not-susceptible to carbapenems is complicated by the diversity of carbapenem-hydrolyzing enzymes that have emerged and the ability of the genes to spread among multiple bacterial species.
Reference Values
Not Detected
Interpretation
A detected result is when blaKPC, blaNDM, blaVIM, blaOXA-48, or blaIMP target DNA is detected. This indicates the presence of gene sequences associated with carbapenem intermediate or resistant results.
A not detected result is when blaKPC, blaNDM, blaVIM, blaOXA-48, and blaIMP target DNA is not detected.
A not detected Xpert Carba-R Assay result does not preclude the presence of other carbapenem-resistance mechanisms.
Cautions
The Xpert Carba-R Assay detects blaKPC, blaNDM, blaVIM, blaOXA-48, and blaIMP from pure colonies and is not for bacterial identification. Detection of these gene sequences does not indicate the presence of viable organisms.
The Xpert Carba-R Assay is not a genetic relatedness subtyping tool and does not report variants of the blaKPC, blaNDM, blaVIM, blaOXA-48, or blaIMP genes.
IMP types detected by this assay include only IMP-1, 2, 4, 6, 10 and 11.
Certain bacterial species, such as Pseudomonas aeruginosa and Acinetobacter baumannii have been shown to exhibit resistance to the carbapenem antimicrobial ertapenem due to intrinsic resistance mechanisms.
The detection of other OXA-carbapenemase genes besides blaOXA-48 and blaOXA-181 has not been evaluated with this assay.
Variants or alterations in primer or probe binding regions may affect detection of current, new, or unknown blaKPC, blaNDM, blaVIM, blaOXA-48, and blaIMP variants, resulting in a false-negative result.
Testing with the Xpert Carba-R Assay should be used as an adjunct to other available methods.
Carbapenem-resistant anaerobes potentially present in fecal specimens have not been evaluated by the Xpert Carba-R Assay.
Erroneous test results might occur from improper culture techniques, failure to follow recommended procedure to prepare the 0.5 McFarland suspension, handling and storage procedures, technical error, sample mix-up, or because the number of organisms in the specimen is too low to be detected by the test. Careful compliance with the instructions in the test instructions for use is necessary to avoid erroneous results.
Supportive Data
The Xpert Carba-R Assay is an FDA-cleared test. The Xpert Carba-R was further verified for use with a Zeptometrix verification panel and organisms (Enterobacterales, Pseudomonas, and Acinetobacter bacteria) with known carbapenem antimicrobial susceptibility test results. The verification passed and is acceptable for use with patient testing.
Method Description
The GeneXpert Dx System automates and integrates sample purification, nucleic acid amplification, and detection of the target sequence in simple or complex specimens using a real-time polymerase chain reaction (PCR) assay. The system requires the use of single-use disposable cartridges that hold the PCR reagents and host the PCR process. Because the cartridges are self-contained, cross-contamination between samples is eliminated. The primers and probes in the Xpert Carba-R Assay detect proprietary sequences for the blaKPC, blaNDM, blaVIM, blaOXA-48, and blaIMP gene sequences associated with carbapenem intermediate or resistant results in gram-negative bacteria.(Package insert: Xpert Carba-R. Cepheid; 301-2438, Rev. G, 7/2020)
Day(s) Performed
Monday through Friday
Report Available
2 to 4 daysSpecimen Retention Time
30 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
87150
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CARBI | Carbapenem Resistance Genes, Varies | 85502-3 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| IMPCB | IMP Resistance Gene | 85498-4 |
| VIMCB | VIM Resistance Gene | 85501-5 |
| NDMCB | NDM Resistance Gene | 73982-1 |
| KPPCB | KPC Resistance Gene | 49617-4 |
| OXACB | OXA-48-like Resistance Gene | 85503-1 |
| CRORG | Organism Identified by Client | In Process |
| CRSRC | Specimen Source | 31208-2 |
Forms
If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.