Test Id : CARNP
Carbapenemase Detection-Carba NP Test, Varies
Useful For
Suggests clinical disorders or settings where the test may be helpful
Confirming carbapenemase production from pure isolates of Enterobacterales or Pseudomonas aeruginosa
Additional Tests
Lists tests that are always performed, at an additional charge, with the initial tests.
| Test Id | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| CARNB | Carbapenemase-Carba NP Test | No | Yes |
Method Name
A short description of the method used to perform the test
Colorimetric Detection of Carbapenem Hydrolysis
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
Specimen Type
Describes the specimen type validated for testing
Varies
Shipping Instructions
1. For shipping information see Infectious Specimen Shipping Guidelines.
2. Place specimen in a large infectious container (T146) and label as an etiologic agent/infectious substance.
Necessary Information
Specimen source and organism identification are required.
ORDER QUESTIONS AND ANSWERS
| Question ID | Description | Answers |
|---|---|---|
| Q00M0076 | Specimen Source (Required) and Organism Identification (Required) |
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Specimen Type: Organism
Supplies: Infectious Container, Large (T146)
Container/Tube: Slant
Specimen Volume: Isolate
Collection Instructions: Submit Enterobacterales or Pseudomonas aeruginosa isolate in pure culture (ie, not mixed with other organisms), actively growing.
Special Instructions
Library of PDFs including pertinent information and forms related to the test
Forms
If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
See Specimen Required
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Agar plate | Reject |
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) | ||
| Refrigerated | |||
Useful For
Suggests clinical disorders or settings where the test may be helpful
Confirming carbapenemase production from pure isolates of Enterobacterales or Pseudomonas aeruginosa
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Gram-negative bacilli (GNB) with acquired carbapenemases have disseminated worldwide, rendering them a global threat. The therapeutic armamentarium for infections caused by carbapenem-resistant Enterobacterales (CRE) is limited, and CRE infections have been associated with significant mortality. Enterobacterales harboring Klebsiella pneumoniae carbapenemase are endemic in some regions of the United States, and although still sporadic, GNB harboring New Delhi metallo-beta-lactamase have been reported from several states. Timely detection of these carbapenemases (along with emerging carbapenemases such as OXA-48 and VIM) is important. Detection is challenging since isolates may have only borderline reductions in susceptibility to carbapenems, and carbapenem resistance may be mediated by mechanisms other than carbapenemases (eg, AmpC or extended-spectrum beta-lactamase with decreased membrane permeability). While molecular methods are confirmatory, testing may not be immediately available and may be limited by the number of targets assayed. The Carba NP test is preferred over the mCIM (modified carbapenem inactivation method) test due to faster turnaround time.
If an isolate is suspected to possess KPC or NDM carbapenemase (eg, due to local epidemiology), Carbapenem Resistance Genes, Molecular Detection, PCR, Varies (CARBI) may be preferred over the Carba NP test.
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.
Negative
Interpretation
Provides information to assist in interpretation of the test results
A positive result indicates production of a carbapenemase by the isolate submitted for testing. A negative result indicates lack of production of a carbapenemase by the isolate submitted for testing.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Results of the Carba NP test should be interpreted along with antimicrobial susceptibility testing results. Phenotypic resistance to carbapenems may be due to traits other than carbapenemase production (eg, AmpC or extended-spectrum beta-lactamase production with decreased membrane permeability). Additionally, a positive test is only indicative of carbapenemase production in general; the assay does not determine the type of carbapenemase present (e.g., NDM-1, KPC, OXA-48-like). If an isolate is suspected to possess KPC or NDM carbapenemase (eg, due to local epidemiology), CARBI / Carbapenem Resistance Genes, Molecular Detection, PCR, Varies may be preferred.
False-negative results may occur due to plasmid loss in isolates submitted for testing, the presence of a nonexpressed carbapenemase gene, or low-level carbapenemase expression.
Supportive Data
We evaluated 271 gram -negative bacilli (of which 131 were carbapenemase producers and of which 201 were Enterobacterales) using the Carba NP test and the modified Hodge test. Sensitivity for detection of carbapenemase production was comparable (Carba NP, 100 versus modified Hodge test, 98%, p=0.08), but the Carba NP test was more specific (100 versus 80%, p<0.0001) and faster.(1)
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Vasoo S, Cunningham SA, Kohner PC, et al. Comparison of a novel, rapid chromogenic biochemical assay, the Carba NP test, with the modified Hodge test for detection of carbapenemase-producing Gram-negative bacilli. J Clin Microbiol. 2013;51(9):3097-3101
2. Nordmann P, Poirel L, Dortet L. Rapid detection of carbapenemase-producing Enterobacteriaceae. Emerg Infect Dis. 2012;18(9):1503-1507
3. Clinical and Laboratory Standards Institute (CLSI): Performance Standards for Antimicrobial Susceptibility Testing. 33rd ed. CLSI Supplement M100, CLSI; 2023
Method Description
Describes how the test is performed and provides a method-specific reference
A pure bacterial isolate is emulsified into cell lysis buffer in 2 tubes: one contains the base indicator solution (phenol red with zinc salts) alone and the other contains the base indicator solution plus imipenem (6 mg/mL). The tubes are incubated at 37 degrees C for 2 hours. A positive reaction is indicated by a color change from red to yellow as a result of hydrolysis of the beta-lactam ring of imipenem.(Vasoo S, Cunningham SA, Kohner PC, et al: Comparison of a novel, rapid chromogenic biochemical assay, the Carba NP test, with the modified Hodge test for detection of carbapenemase-producing Gram-negative bacilli. J Clin Microbiol. 2013;51[9]:3097-3101)
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 Friday
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.
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Fees :
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
- Authorized users can sign in to Test Prices for detailed fee information.
- Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
- Prospective clients should contact their account representative. For assistance, contact Customer Service.
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 was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
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 |
|---|---|---|
| CARNP | Carbapenemase-Carba NP Test | 74676-8 |
| 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.
|
|---|---|---|
| CARNP | Carbapenemase-Carba NP Test | 74676-8 |