Test Catalog

Test Id : MARP

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mecA, Molecular Detection, PCR, Varies

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Overview

Test Catalog

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

Detecting mecA in staphylococcal bacterial isolates

 

Evaluating treatment options when oxacillin or cefoxitin breakpoints are unavailable (eg, some Staphylococcus species, not Staphylococcus aureus)

 

Predicting antimicrobial resistance when bacterial growth is inadequate for phenotypic antimicrobial susceptibility testing (eg, staphylococcal small colony variants)

 

Assessing discrepancies between cefoxitin and oxacillin phenotypic testing results

Highlights

This is a rapid molecular test that detects mecA DNA associated with prediction of antimicrobial resistance to methicillin and other applicable beta-lactam antibiotics in isolates of Staphylococcus species.

Method Name
A short description of the method used to perform the test

Real-Time Polymerase Chain Reaction (PCR) using LightCycler with Amplified Product Detection using Fluorescent Resonance Energy Transfer (FRET) Hybridization Probes

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

Yes

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

mecA PCR

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

mecA

Staphylococcus

Staph

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 and label as an etiologic agent/infectious substance.

Necessary Information

Organism identification and specimen source are required.

ORDER QUESTIONS AND ANSWERS

Question ID Description Answers
MASRC Specimen Source
MAORG Organism Identified by Client

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

Supplies: Infectious Container, Large (T146)

Container/Tube: Agar slant or other appropriate media

Specimen Volume: Organism in pure culture

Collection Instructions:

1. Perform isolation of bacteria.

2. Organism must be in pure culture, actively growing. Do not submit mixed cultures.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

See Specimen Required

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

Agar plate
Mixed culture 		 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)
Frozen
Refrigerated

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

Detecting mecA in staphylococcal bacterial isolates

 

Evaluating treatment options when oxacillin or cefoxitin breakpoints are unavailable (eg, some Staphylococcus species, not Staphylococcus aureus)

 

Predicting antimicrobial resistance when bacterial growth is inadequate for phenotypic antimicrobial susceptibility testing (eg, staphylococcal small colony variants)

 

Assessing discrepancies between cefoxitin and oxacillin phenotypic testing results

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

Bacteria can acquire resistance to certain beta-lactam antibiotics through a variety of mechanisms. One such mechanism is the mecA gene. The mecA gene encodes penicillin-binding protein 2a (PBP2a), which is a PBP that has a low affinity for beta-lactam antibiotics. Bacteria expressing this gene can maintain cell wall synthesis even in the presence of beta-lactam antibiotics. Clinically significant mecA-mediated resistance is restricted to staphylococci.

 

Testing of bacterial isolates by molecular methods may be needed when oxacillin or cefoxitin breakpoints are unavailable (eg, Staphylococcus species, not Staphylococcus aureus) or when discrepancies between cefoxitin and oxacillin phenotypic antimicrobial susceptibility testing results exist. Use of this assay may also be helpful when isolates do not grow adequately for phenotypic antimicrobial susceptibility testing (eg, staphylococcal small colony variants; SCV).

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 applicable

Interpretation
Provides information to assist in interpretation of the test results

This polymerase chain reaction (PCR) detects the mecA gene. A positive result for this mecA PCR test strongly suggests resistance to beta-lactam antibiotics other than ceftaroline in a staphylococcal isolate. If the mecA PCR test is positive, and the patient is on a beta-lactam antimicrobial predicted to be resistant, the clinician should consider escalating the antimicrobial treatment to an appropriate therapy.

 

A negative result indicates the absence of detectable DNA.

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

Only pure isolates of staphylococcal species should be tested.

 

This test should be used in conjunction with phenotypic antimicrobial susceptibility tests, when available, and interpreted considering the patient's clinical condition.

 

False-negative results may occur due to inhibition of polymerase chain reaction, sequence variability underlying primers and probes, or the presence of the mecA genes in quantities lower than the limit of detection of the assay.

Supportive Data

This test demonstrated 100% concordance for testing performed on 72 methicillin-resistant Staphylococcus aureus (MRSA) isolates and 42 methicillin-susceptible S aureus (MSSA) isolates.

 

In addition, this test demonstrated 100% concordance for 43 methicillin-resistant Staphylococcus isolates, not S aureus, and 96.5% concordance for 57 methicillin-susceptible Staphylococcus isolates, not S aureus.

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

Miragaia M: Factors contributing to the evolution of mecA-mediated beta-lactam resistance in Staphylococci: Update and new insights from whole genome sequencing (WGS). Front Microbiol. 2018 Nov 13;9:2723. doi: 10.3389/fmicb.2018.02723

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

Nucleic acids are released from bacterial isolates followed by polymerase chain reaction (PCR), which employs a target-specific detection system, including primers and fluorescent resonance energy transfer (FRET) hybridization probes that target the mecA gene. The LightCycler instrument amplifies and monitors target nucleic acid sequences by fluorescence during PCR cycling. This is an automated PCR system that rapidly detects amplified product development through stringent air-controlled temperature cycling and capillary cuvettes. Detection of amplified products is based on the FRET principle. For FRET product detection, a hybridization probe with a donor fluorophore, fluorescein, on the 3' end is excited by an external light source, which emits light that is absorbed by a second hybridization probe with an acceptor fluorophore. The acceptor fluorophore then emits light of a different wavelength that is measured with a signal proportional to the amount of specific PCR product. The detection process is completed in a closed system.(Cockerill FR, Uhl JR: Applications and challenges of real-time PCR for the clinical microbiology laboratory. In: Reischl U, Wittwer C, Cockerill F, eds. Rapid Cycle Real-Time PCR Methods and Applications. Springer-Verlag; 2002:3-27; Simner PJ, Humphries R: Special phenotypic methods for detecting antibacterial resistance: In: Carroll KC, Pfaller MA, eds. Manual of Clinical Microbiology. 12th ed. ASM Press; 2019:1316-1347)

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

No

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.

2 to 5 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

Rochester

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.

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.

87150

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
MARP mecA PCR 48813-0
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.
MASRC Specimen Source 39111-0
MAORG Organism Identified by Client 43409-2
607725 mecA PCR 48813-0

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