Test Catalog

Test Id : GAPCR

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Streptococcus Group A, Molecular Detection, PCR, Throat

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Overview

Test Catalog

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

Detecting group A streptococcal infections in patients with signs and symptoms of pharyngitis using a throat swab specimen

 

The test is not intended for monitoring treatment for group A Streptococcus infections.

Highlights

This test provides rapid detection of Streptococcus pyogenes/Group A Streptococcus in patients with pharyngitis.

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

Real-Time Polymerase Chain Reaction (PCR)

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

Group A Streptococcus PCR, Throat

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

Strep

Group A Streptococcus

S. pyogenes

S pyogenes

Streptococcus pyogenes

Specimen Type
Describes the specimen type validated for testing

Varies

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

Patient Preparation: Do not collect throat swab specimens immediately after use of antiseptic mouthwash.

Specimen Type: Throat swab

Supplies: BD E-Swab (T853)

Container/Tube:

Preferred: BD Liquid Amies Elution Swab (ESwab)

Acceptable: Copan Liquid Amies Elution Swab (ESwab)

Specimen Volume: Entire collection/1 ESwab

Collection Instructions:

1. Must be collected and transported using the ESwab collection kit.

2. Using a tongue blade to hold the tongue down, firmly rub the swab over the tonsils, posterior pharynx, and any areas of inflammation with exudate. Ensure that areas with exudate or inflammation are swabbed.

3. Avoid the tongue, teeth, and gums as the swab is withdrawn.

4. Insert the swab back into the ESwab transport tube and break the swab at the indicated score line.

5. Label specimen according to policy.

6. Send refrigerated. Do not freeze.

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

Specimens collected in media other than ESwab collection kit 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 Refrigerated (preferred) 6 days
Ambient 48 hours

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

Detecting group A streptococcal infections in patients with signs and symptoms of pharyngitis using a throat swab specimen

 

The test is not intended for monitoring treatment for group A Streptococcus infections.

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

Group A streptococci are gram-positive, beta-hemolytic disease-causing bacteria that commonly cause infections in the throat (pharyngitis or strep throat) or on skin (cellulitis and impetigo) and can cause a wide range of other infections (eg, sepsis, pneumonia, and meningitis). Pharyngitis may also be caused by other bacteria, including Neisseria gonorrhoeae and Corynebacterium diphtheriae, for which specific culture methods are required. If left untreated, mild infections can lead to more serious infections. The most severe but least common forms of invasive Group A streptococcal disease (GAS) are necrotizing fasciitis and streptococcal toxic shock syndrome. Several million cases of strep throat and impetigo occur each year with approximately 9000 to 11,500 cases of invasive GAS disease occurring in the United States, resulting in 1000 to 1800 deaths.(1) Treating an infected person with an appropriate antibiotic generally prevents the spread of the infection and reduces the risk of post-infectious complications, such as rheumatic fever and acute glomerular nephritis.(2)

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

Positive: Streptococcus pyogenes DNA is detected.

Negative: Streptococcus pyogenes DNA is not detected.

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

Additional follow-up testing by culture is required if the Xpert Xpress Strep A test result is negative and clinical symptoms persist or if there is an outbreak of acute rheumatic fever.

 

As with many diagnostic tests, negative results from the Xpert Xpress Strep A test do not preclude a Strep A infection and should not be used as the sole basis for treatment or other patient management decisions. The Xpert Xpress Strep A test does not differentiate asymptomatic carriers of Group A streptococci from those exhibiting streptococcal infection. The results from the Xpert Xpress Strep A test should be interpreted in conjunction with other laboratory and clinical data available to the clinician.

 

A negative test result does not exclude the possibility of infection because the test result may be affected by improper specimen collection, technical error, sample mix-up, or because the number of organisms in the sample is below the limit of detection of the test.(3)

 

Because the detection of Streptococcus pyogenes is dependent on the organism's DNA present in the sample, reliable results are dependent on proper specimen collection, handling, and storage.

 

The Xpert Xpress Strep A test has been validated only with Copan Liquid Amies Elution Swab (ESwab) Collection Kit (Copan 480C, Copan 480CE, or Copan 480CFA) or equivalent.

 

Variants or nucleotide alterations (ie, polymorphisms) in primer or probe binding regions may affect detection of new or unknown S pyogenes strains resulting in a false-negative result.

 

This test has not been evaluated for patients without signs and symptoms of pharyngitis.

 

This test cannot rule out pharyngitis caused by disease-causing organisms other than Group A streptococci.

 

The analyte target (bacterial nucleic acid) may persist in vivo, independent of pathogen viability. Detection of the analyte target does not imply that the corresponding pathogen is either infectious or is the causative agent of the clinical symptoms.(3)

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

1. Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases, Division of Bacterial Diseases. Active Bacterial Core Surveillance (ABCs) Report: group A Streptococcus, 2003. CDC. 2004. Accessed January 31, 2024. Available at www.cdc.gov/abcs/reports-findings/survreports/gas03.pdf

2. Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases, Division of Bacterial Diseases. Scarlet Fever: All You Need to Know. CDC. Updated May 10, 2023. Accessed January 31, 2024. Available at www.cdc.gov/groupastrep/diseases-public/scarlet-fever.html

3. Package insert: Xpert Xpress Strep A. Cepheid; 301-9326 Rev. D, 06/2019

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 extraction and amplification, and detection of the target sequence using real-time polymerase chain reaction (PCR). The system requires 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 minimized.

 

The Xpert Xpress Strep A test, performed on the GeneXpert Instrument Systems, is a rapid, qualitative test using real-time PCR to detect Streptococcus pyogenes DNA. The assay includes a sample processing control to ensure an adequate amplification process and to monitor for the presence of inhibitors in the PCR reaction. A probe check control verifies reagent rehydration, PCR tube filling, and all reaction components, including probes and dyes, are present and functional in the cartridge.(Package insert: Xpert Xpress Strep A. Cepheid; 301-9326, Rev. D, 06/2019)

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 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.

Same day/1 day

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

6 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 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.

87651

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
GAPCR Group A Streptococcus PCR, Throat 60489-2
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.
GAPCR Group A Streptococcus PCR, Throat 60489-2

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 | 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

Test Update Resources

Change Type Effective Date
Test Status - Test Resumed 2023-08-08
Test Status - Test Down 2023-05-04
New Test 2023-02-14