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HelpTest Code SPNC Streptococcus pneumoniae Antigen, Spinal Fluid
Reporting Name
Streptococcus pneumoniae Ag, CSFUseful For
Rapid diagnosis of pneumococcal meningitis
Method Name
Immunochromatographic Membrane Assay
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
CSFAdditional Testing Requirements
According to the College of American Pathologists (CAP, IMM.41830), cerebrospinal fluid (CSF) samples collected to make an initial diagnosis and submitted for detection of Streptococcus pneumoniae antigen testing should also be submitted for routine bacterial culture. Mayo Clinic Laboratories recommends that CSF bacterial cultures be performed at the originating site.
Specimen Required
Container/Tube: Sterile vial
Specimen Volume: 1 mL
Collection Instructions: Submit specimen collected in vial 2, if possible. If not possible, note which vial from which the aliquot was obtained.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| CSF | Refrigerated (preferred) | 14 days | |
| Frozen | 14 days |
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | OK |
Reference Values
Negative
Reference values apply to all ages.
Day(s) Performed
Monday through Sunday
CPT Code Information
87899
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| SPNC | Streptococcus pneumoniae Ag, CSF | 20489-1 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 31667 | Streptococcus pneumoniae Ag, CSF | 20489-1 |
Clinical Information
Streptococcus pneumoniae is the most frequently encountered bacterial agent of community-acquired pneumonia, and can also be an agent of bacterial meningitis. Because of the significant morbidity and mortality associated with pneumococcal pneumonia, septicemia, and meningitis, it is important to have diagnostic test methods available that can provide a rapid diagnosis. In instances where empirical antibiotics are being considered prior to culture confirmation, antigen testing may be useful.
Interpretation
A positive result supports a diagnosis of pneumococcal meningitis.
A negative result suggests that pneumococcal antigen is absent in the cerebrospinal fluid (CSF). However, infection due to Streptococcus pneumoniae cannot be ruled out since the antigen present in the specimen may be below the lower limit of detection of the test.
If pneumococcal meningitis is suspected, bacterial culture and Gram stain analysis on CSF should be performed.
Cautions
A negative result does not exclude Streptococcus pneumoniae infection.
A diagnosis of Streptococcus pneumoniae infection must take into consideration all test results, culture results, and the clinical presentation of the patient.
Streptococcus pneumoniae vaccine may cause false-positive results, especially in patients who received the vaccine 5 or fewer days prior to specimen collection.
This assay has not been validated for use with body fluids other than urine or cerebrospinal fluid.
The performance of this assay has not been established for patients on antibiotic treatment for more than 24 hours.
Method Description
The BinaxNOW Streptococcus pneumoniae test is an immunochromatographic membrane assay used to detect pneumococcal-soluble antigen in cerebrospinal fluid. Rabbit anti-Streptococcus pneumoniae and anti-species antibodies are conjugated to visualizing particles that are dried onto an inert fibrous support. The resulting conjugate pad and the striped membrane are combined to construct the test strip.
To perform the test, a swab is dipped into the specimen, removed, and then inserted into the test device. Reagent A, a buffer solution, is added from a dropper bottle. The device is then closed, bringing the sample into contact with the test strip. Pneumococcal antigen present in the sample reacts to bind anti-Streptococcus pneumoniae conjugated antibody, forming the sample line. Immobilized control antibody captures anti-species conjugate forming the control line.
Test results are interpreted by the presence or absence of visually detectable pink-to-purple-colored lines. A positive test result, read in greater than or equal to 15 minutes depending on the concentration of antigen present in the sample, will include the detection of both a sample and control line. A negative test result, read in 15 minutes, will produce only a control line, indicating that Streptococcus pneumoniae antigen was not detected in the sample. Failure of the control line to appear, whether the sample line is present or not, indicates an invalid assay.(Package insert: BinaxNOW Streptococcus pneumoniae Test. Abbott; 01/15/2020)