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Test Code HPFLU Influenza Virus Type A and Type B and Respiratory Syncytial Virus (RSV) RNA, Molecular Detection, PCR, Varies


Specimen Required


Preferred:

Specimen Type: Nasopharyngeal swab

Container/Tube: Sterile container with viral transport media

Specimen Volume: Entire specimen with a minimum of 1.5 mL (maximum 3 mL) of transport media.

Collection Instructions:

1. Collect specimen by swabbing back and forth over mucosa surface to maximize recovery of cells.

2. Swab must be placed into viral transport media (eg, M4-RT, M4 or M5), saline, or phosphate buffered saline (PBS). Media should not contain guanidine thiocyanate (GTC).

 

Specimen Type: Bronchoalveolar lavage fluid

Container/Tube: Sterile container

Specimen Volume: 0.6 mL

Additional Information: Do not aliquot into viral transport media.

 

Acceptable:

Specimen Type: Oropharyngeal (throat) swab, nasal mid-turbinate, or nares/nasal swab

Supplies:

-Culturette (BBL Culture Swab) (T092)

-Mid Turbinate (MT) Swab (FLOQSwab/COPAN) (T864)

-Swab, Sterile Polyester (T507)

Container/Tube: Sterile container with transport media

Specimen Volume: Entire specimen with a minimum of 1.5 mL (maximum 3 mL) of transport media.

Preferred: BBL Culture Swab, COPAN Mid-turbinate Swab

Acceptable: Dacron-tipped swab with plastic handle

Collection Instructions: Swab must be placed into viral transport media (eg, M4-RT, M4, or M5), saline, or PBS. Media should not contain guanidine thiocyanate (GTC).

 

Specimen Type: Bronchial washings, endotracheal aspirate, sputum

Container/Tube: Sterile container

Specimen Volume: 0.6 mL

Additional Information: Do not aliquot into viral transport media.


Useful For

Simultaneous detection of influenza A virus, influenza B virus, and respiratory syncytial virus in upper or lower respiratory tract specimens from individuals with flu-like illnesses

Method Name

Multiplex Reverse Transcriptase, Real-Time Polymerase Chain Reaction (RT-qPCR)

Reporting Name

Influenza A/B and RSV, PCR, Varies

Specimen Type

Varies

Specimen Minimum Volume

Upper respiratory tract swab: See Specimen Required; Lower respiratory specimens: 0.3 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Frozen (preferred) 14 days
  Refrigerated  72 hours

Reject Due To

Bloody specimen Calcium alginate-tipped swab
Wooden shaft swab
Dry swab Glass transport media tubes
Transport swab containing gel or charcoal additive Sample tubes containing guanidine isothiocyanate, guanidine thiocyanate, or guanidine hydrochloride		 Reject

Clinical Information

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, older individuals, patients who are immunocompromised, and those with impaired lung function, are at risk for serious complications. In the United States, influenza results in 10,000 to 30,000 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.

 

Influenza infection may be treated with supportive therapy as well as antiviral drugs, such as the neuraminidase inhibitors, oseltamivir (Tamiflu) and zanamivir (Relenza). These drugs are most effective when given within the first 48 hours of infection, so prompt diagnosis and treatment are essential for proper management.

 

Respiratory syncytial virus (RSV) is a respiratory virus that also infects the human respiratory tract, causing an influenza-like illness. Most otherwise healthy people recover from RSV infection in 1 to 2 weeks, but infection can be severe in infants, young children, and older adults. RSV is the most common cause of bronchiolitis (inflammation of the small airways in the lung) and pneumonia in children younger than 1 year in the United States. It is increasingly recognized as a frequent cause of respiratory illness in older adults.(2)

 

RSV and influenza viruses can be detected in respiratory secretions, including upper and lower respiratory tract specimens, by molecular test methods. Nasopharyngeal swabs or aspirates are the preferred specimen types for detection of influenza A virus, influenza B virus, and RSV. Nasal swabs have been shown to provide comparable yield to nasopharyngeal specimens for molecular detection of influenza A and B viral RNA but not RSV RNA.(3-4)

Reference Values

Undetected

Interpretation

A "Detected" (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 one 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.

 

An “Undetected” (negative) test result suggests that the patient is not infected with influenza A virus, influenza B virus, or respiratory syncytial virus (RSV).

 

An "Inconclusive" result indicates that the presence or absence of influenza A virus, influenza B virus, and RSV in the specimen could not be determined with certainty after repeat testing in the laboratory, possibly due to real-time, reverse transcription polymerase chain inhibition. Submission of a new specimen for testing is recommended.

Cautions

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. A nasopharyngeal swab and bronchoalveolar lavage fluid are the preferred specimen types for optimal detection of respiratory syncytial virus (RSV) RNA in the upper and lower respiratory tracts, respectively.

 

The test is specific for influenza A virus, influenza B virus, and RSV; 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 viral RNA but does not distinguish among the different viral subtypes.

 

"Undetected' (negative) results do not preclude infection with influenza A virus, influenza B virus, or RSV and should not be used as the sole basis for treatment or other patient management decisions.

 

This assay detects both replicating and nonreplicating virus (ie, remnant viral nucleic acid). Test performance depends on viral load in the specimen and may not correlate with cell culture performed on the same specimen.

 

The assay has not been US Food and Drug Administration approved for detection of influenza A H7N9, though comparison of primer and probe sequences indicates that the assay will detect the H7N9 viral subtype.

Day(s) Performed

Monday through Sunday

Report Available

Same day/1 to 2 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

87631

LOINC Code Information

Test ID Test Order Name Order LOINC Value
HPFLU Influenza A/B and RSV, PCR, Varies 92143-7

 

Result ID Test Result Name Result LOINC Value
HPFLS Influenza A/B and RSV, Source 31208-2
610412 Influenza A virus PCR 92142-9
610413 Influenza B virus PCR 92141-1
610414 Respiratory Syncytial Virus, PCR 92131-2

Forms

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