Test Catalog

Test Id : CARBI

Carbapenem Resistance Genes, Molecular Detection, PCR, Varies

Useful For
Suggests clinical disorders or settings where the test may be helpful

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
A short description of the method used to perform the test

Real-Time Polymerase Chain Reaction (PCR)/Reverse Transcription PCR

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Carbapenem Resistance Genes, Varies

Lists additional common names for a test, as an aid in searching

Carbapenem resistant CRE

Carbapenem resistant Enterobacteriaceae

Carbapenem resistant Enterobacterales

Carbapenem resistant Pseudomonas aeruginosa

Carbapenem resistant Acinetobacter species

Carbapenem resistant gram-negative bacilli

Carbapenem non-susceptible











Specimen Type
Describes the specimen type validated for testing


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.


Question ID Description Answers
CRSRC Specimen Source

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

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.


If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Agar plate
Mixed culture

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Varies Ambient (preferred)

Useful For
Suggests clinical disorders or settings where the test may be helpful

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

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

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
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.

Not Detected

Provides information to assist in interpretation of the test results

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.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

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.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Bush K, Bradford PA. Epidemiology of beta-lactamase-producing pathogens. Clin Microbiol Rev. 2020;33(2): e00047-19

2. Tenover FC, Nicolau DP, Gill CM. Carbapenemase-producing Pseudomonas aeruginosa - an emerging challenge. Emerg Microbes Infect. 2022;11(1):811-814

3. Clinical and Laboratory Standards Institute (CLSI). Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically. 11th ed. CLSI standard M07. CLSI; 2018

Method Description
Describes how the test is performed and provides a method-specific reference

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)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Sunday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

2 to 4 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

30 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


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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 instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
CARBI Carbapenem Resistance Genes, Varies 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.
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 43409-2
CRSRC Specimen Source 31208-2

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | PHP Pdf | CMS Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports