Test ID: FLUAB
Influenza Virus Type A and Type B, Molecular Detection, PCR
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Rapid and accurate detection of influenza A and influenza B in a single test
Method Name A short description of the method used to perform the test
Multiplex Real-Time Polymerase Chain Reaction (RT-PCR)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Forms: If not ordering electronically, submit a Microbiology Request Form (Supply T244) with the specimen.
Specimen source is required.
Submit only 1 of the following specimens:
Specimen Type: Aspirate or washing
Sources: Nasal or nasopharyngeal
Container/Tube: Sterile container
Specimen Volume: 0.5 mL
Specimen Type: Swab
Sources: Nasopharyngeal or throat
Container/Tube:
Preferred: Nasopharyngeal swab collected using BBL CultureSwab (T515)
Acceptable: Throat swab collected using BBL CultureSwab (T092) or Dacron-tipped swab (T507) placed in M5 media
Specimen Volume: Swab
Specimen Type: Respiratory
Sources: Bronchial washing or bronchoalveolar lavage
Container/Tube: Sterile container
Specimen Volume: 0.5 mL
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | Calcium alginate-tipped swab, wood swab, or transport swab containing gel |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Refrigerated | 7 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Influenza, otherwise known as the "flu," is an acute, contagious respiratory illness caused by influenza A, B, and C viruses. Of these, only influenza A and B are thought to cause significant disease, with infections due to influenza B usually being milder than infections with influenza A. Influenza A viruses are further categorized into subtypes based on the 2 major surface protein antigens: hemagglutinin (H) and neuraminidase (N).
Common symptoms of influenza infection include fever, chills, sore throat, muscle pains, severe headache, weakness/fatigue, and a nonproductive cough. Certain patients, including infants, the elderly, the immunocompromised, and those with impaired lung function, are at risk for serious complications. In the United States, influenza results in approximately 36,000 deaths and more than 200,000 hospitalizations each year.(1)
In the northern hemisphere, annual epidemics of influenza typically occur during the fall or winter months. However, the peak of influenza activity can occur as late as April or May, and the timing and duration of flu seasons vary. In 2009 to 2010, a novel influenza virus (called 2009 H1N1, previously "swine" flu) appeared in Mexico and quickly spread worldwide, causing the first influenza pandemic in more than 40 years. The resultant influenza season had an atypical distribution, with illness occurring during normally low-incidence months. The Centers for Disease Control and Prevention (CDC) now predicts that the influenza season will return to a winter distribution.(1)
Influenza infection may be treated with supportive therapy, as well as antiviral drugs such as the neuraminidase inhibitors, oseltamivir (TAMIFLU) and zanamivir (RELENZA), and the adamantanes, rimantadine and amantadine. These drugs are most effective when given within the first 48 hours of infection, so prompt diagnosis and treatment are essential for proper management.
Influenza virus RNA can be detected by PCR in respiratory secretions, including upper and lower respiratory specimens. Nasopharyngeal swabs or aspirates are the preferred specimen types for detection of RNA from influenza A and influenza B. Nasal swabs have also been shown to provide equivalent yield to nasopharyngeal specimens for molecular detection of influenza A and B RNA. Tracheal aspirates are generally not acceptable for testing due to the viscous nature of these specimens.
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
A positive test result indicates that the patient is presumptively infected with the indicated virus. The test does not indicate the stage of infection. Rarely, more than 1 virus may be detected from the same patient specimen. Laboratory test results should always be considered in the context of clinical observations and epidemiologic data in making a final diagnosis.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Given that influenza A and B and respiratory syncytial virus (RSV) can cause identical appearing clinical illness, this test should typically be ordered as a panel that includes both influenza A/B and RSV (#60552 Influenza Virus Type A and Type B, and Respiratory Syncytial Virus (RSV), Molecular Detection, PCR).
This test has been designed to minimize the likelihood of false-positive test results. However, should false-positive results occur, risks to patients could include a recommendation for quarantine of household or other close contacts, a recommendation for patient isolation that might limit contact with family or friends, the ability to work, or the ability to receive certain medical care, prescription of an antiviral drug or other therapy, or other unintended adverse effects.
The sensitivity of the assay is very dependent upon the quality of the specimen submitted. Nasopharyngeal or nasal specimens provide optimal detection of influenza A and B RNA. However, the test is validated for use with most upper and lower respiratory specimens, including nasal swabs, throat swabs, bronchoalveolar lavage specimens, and bronchial brushings/washings. Tracheal aspirates are not acceptable for testing due to the viscous nature of these specimens.
This test should not be performed unless the patient meets clinical and epidemiologic criteria for testing.
The test is specific for influenza A and influenza B, therefore, the results do not exclude the possibility of infection with other respiratory viruses. Influenza C virus is not detected by this assay.
This assay detects influenza A virus RNA, but does not distinguish between the different subtypes of influenza A.
Negative results do not preclude infection with influenza A or influenza B viruses and should not be used as the sole basis for treatment or other patient management decisions.
This assay detects both viable and nonviable virus. Test performance depends on viral load in the specimen and may not correlate with cell culture performed on the same specimen.
Performance of the assay has not been established for monitoring antiviral treatment or duration of infection with influenza viruses.
Supportive Data
All testing was performed on the Roche LightCycler 480 instrument using the Prodesse ProFlu+ test for Influenza A, Influenza B, and respiratory syncytial virus (RSV).
Accuracy:
Influenza A, 2009 H1N1
Twenty-eight clinical specimens were tested by this Prodesse ProFlu+ assay and a validated laboratory-developed test (LDT) for influenza A targeting the matrix gene. Eighteen positives and 8 negatives were detected by both methods. Two additional low-positive specimens were detected by the ProFlu+ that were not initially detected by the LDT, giving a sensitivity of 100% and specificity of 80%. These 2 specimens were detected by the LDT on repeat testing.
Spiked specimens were used to supplement influenza A clinical specimens. Sixty negative patient specimen matrices (30 swab/upper respiratory and 30 nonswab respiratory specimens) were spiked with dilutions of culture-positive 2009 H1N1 influenza A at the limit of detection and run in a blinded manner with 60 negative patient specimens. The 60 spiked specimens were positive and the 60 nonspiked specimens were negative (100% concordance).
Influenza A, H3N2
Thirty negative patient specimen matrices (swab/upper respiratory) were spiked with dilutions of culture-positive influenza A H3N2 at the limit of detection and run in a blinded manner with 30 negative specimens. The 30 spiked specimens were positive and the 30 nonspiked specimens were negative (100% concordance).
Influenza A, Seasonal H1N1
Thirty negative patient specimen matrices (swab/upper respiratory) were spiked with dilutions of culture-positive influenza A seasonal H1N1 at the limit of detection and run in a blinded manner with 30 negative specimens. The 30 spiked specimens were positive and the 30 nonspiked specimens were negative (100% concordance).
Influenza B
Sixty negative patient specimen matrices (30 swab/upper respiratory and 30 nonswab respiratory specimens) were spiked with dilutions of culture-positive influenza B virus at the limit of detection and run in a blinded manner with 60 negative specimens. Of the spiked specimens, 59 were positive and 1 was not detected. All 60 of nonspiked specimens were negative.
Precision:
-Qualitative intra-assay precision=100%; standard deviation <0.9 PCR cycles
-Qualitative interassay=98%; standard deviation <0.9 PCR cycles
Limit of detection (LoD):
-The LoD using a quantified plasmid standard was 10 targets/microliter for swab respiratory specimens, and 25 targets/microliter for nonswab specimens.
-The LoD using quantitated cells cultures (TCID50) was 1 TCID50/mL for influenza A and 1 TCID50/mL for influenza B.
Specificity:
No cross-reactivity observed using a panel of 34 viruses, bacteria, fungi, and mycobacteria that may be found in respiratory specimens.
Inhibition Rate:
No inhibition was seen in any of the extracted lower or upper respiratory specimens when tested at the LoD.
Reference Range:
A review of the literature indicates that the reference range is "negative" for this assay. This assay is designed to detect influenza A or B and is to be used for patients with a clinical history and symptoms consistent with this disease. This test should not be used to screen healthy patients.
Reportable Range:
This is a qualitative assay and results are reported as negative or positive for influenza A or influenza B.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Centers for Disease Contol and Prevention. Seasonal Influenza: http://www.cdc.gov/flu/; Novel H1N1 Flu (Swine Flu): Available from: http://www.cdc.gov
2. Meerhoff TJ, Houben ML, Coenjaerts FE, et al: Detection of multiple respiratory pathogens during primary respiratory infection: nasal swab versus nasopharyngeal aspirate using real-time polymerase chain reaction. Eur J Clin Microbiol Infect Dis 2010;29:365-371
3. Heikkinen T, Marttila J, Salmi AA, Ruuskanen O: Nasal swab versus nasopharyngeal aspirate for isolation of respiratory viruses. J Clin Microbiol 2002;40(11):4337-4339
Method Description Describes how the test is performed and provides a method-specific reference
The Prodesse ProFlu+ assay is a real-time, reverse-transcription PCR (rRT-PCR) assay for simultaneous detection of influenza A, influenza B, and respiratory syncytial virus (RSV). This assay is modified from the U.S. Food and Drug Administration-approved version by use of an alternate amplification system (Roche LightCycler 480).
Viral nucleic acid is extracted by the MagNA Pure automated instrument (Roche Applied Science) from upper and lower respiratory specimens including nasal, throat, and nasopharyngeal swabs, bronchoalveolar lavage, nasopharyngeal aspirates, and bronchial washings and brushings. Reverse transcription produces cDNA from RNA in the extracted specimen, which is then amplified and detected by use of Taqman probes on the Roche LightCycler 480 instrument. Positive results are detected when a fluorescent signal is generated that crosses the threshold of background fluorescence. (Unpublished Mayo method)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Sunday
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
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's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
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 Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
87502
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| SRC76 | Influenza Source | 31208-2 |
| 32292 | Influenza Type A | 34487-9 |
| 32293 | Influenza Type B | 40982-1 |
External
link
PDF
document
Excel
document
Word
document