Test Catalog

Test Id : ASPAG

Aspergillus (Galactomannan) Antigen, Serum

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

Aiding in the diagnosis of invasive aspergillosis

 

Assessing response to therapy

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

Enzyme Immunoassay (EIA)

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

Aspergillus Ag, S

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

Aspergillosis

Galactomannan

Invasive Aspergillosis

Platelia Aspergillus Ag

Specimen Type
Describes the specimen type validated for testing

Serum SST

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

Container/Tube: Serum gel (red top tubes are not acceptable)

Specimen Volume: 1.5 mL

Collection Instructions:

1. Avoid exposure of specimen to atmosphere to prevent sample contamination from environment.

2. Centrifuge and send specimen in original tube. Do not aliquot or open tube.

Forms

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

1 mL

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

Gross hemolysis Reject
Gross lipemia 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
Serum SST Refrigerated (preferred) 14 days SERUM GEL TUBE
Frozen 14 days SERUM GEL TUBE

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

Aiding in the diagnosis of invasive aspergillosis

 

Assessing response to therapy

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

Invasive aspergillosis (IA) is a severe infection that occurs in patients with prolonged neutropenia, following transplantation or in conjunction with aggressive immunosuppressive regimens (eg, prolonged corticosteroid usage, chemotherapy). The incidence of IA is reported to vary from 5% to 20% depending on the patient population. IA has an extremely high mortality rate of 50% to 80% due in part to the rapid progression of the infection (ie, 1-2 weeks from onset to death). Approximately 30% of cases remain undiagnosed and untreated at death.

 

Definitive diagnosis of IA requires histopathological evidence of deep-tissue invasion or a positive culture. However, this evidence is often difficult to obtain due to the critically ill nature of the patient and the fact that severe thrombocytopenia often precludes the use of invasive procedures to obtain a quality specimen. The sensitivity of culture in this setting also is low, reportedly ranging from 30% to 60% for bronchoalveolar lavage fluid. Accordingly, the diagnosis is often based on nonspecific clinical symptoms (unexplained fever, cough, chest pain, dyspnea) in conjunction with radiologic evidence (computed tomography: CT scan); definitive diagnosis is often not established before fungal proliferation becomes overwhelming and refractory to therapy.

 

Recently, a serologic assay was approved by the FDA for the detection of galactomannan, a molecule found in the cell wall of Aspergillus species. Serum galactomannan can often be detected a mean of 7 to 14 days before other diagnostic clues become apparent, and monitoring of galactomannan can potentially allow initiation of preemptive antifungal therapy before life-threatening infection occurs.

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.

<0.5 index

Reference values apply to all ages.

Interpretation
Provides information to assist in interpretation of the test results

A positive result supports a diagnosis of invasive aspergillosis (IA). Positive results should be considered in conjunction with other diagnostic procedures, such as microbiologic culture, histological examination of biopsy specimens, and radiographic evidence. See Cautions.

 

A negative result does not rule out the diagnosis of IA. Repeat testing is recommended if the result is negative but IA is suspected. Patients at risk of IA should have a baseline serum tested and should be monitored twice a week for increasing galactomannan antigen levels.

 

Galactomannan antigen levels may be useful in the assessment of therapeutic response. Antigen levels decline in response to antimicrobial therapy.

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

False-positive results are reported to occur at rates of 8% to 14% with this assay. For all positive patients, it is recommended that a new aliquot of the same specimen be repeated, as well as collection of a new specimen from the patient for follow-up testing. Two or more consecutive positive results should be obtained from separately collected specimens before the patient is considered to have a positive Aspergillus antigen test.

 

Numerous foods (pasta, rice, etc) contain galactomannan. It is thought that damage to the gut wall by cytotoxic therapy, irradiation, or graft-versus-host disease enables translocation of the galactomannan from the gut lumen into the blood and may be partially responsible for the high false-positive rate of this assay.

 

Other genera of fungi such as Penicillium and Paecilomyces have shown reactivity with the rat EBA-2 monoclonal antibody used in the assay. These species are rarely implicated in invasive fungal disease. Cross reactivity with Alternaria species also has been reported.

 

Semisynthetic antibiotics such as piperacillin, amoxicillin, and Augmentin, which are based on natural compounds derived from the genus Penicillium, have been demonstrated to cross-react with the rat EBA-2 monoclonal antibody used in the assay.

 

The specificity of the assay for Aspergillus species cannot exclude the involvement of other fungal pathogens with similar clinical presentations such as Fusarium, Alternaria, and Mucorales.

 

The performance of the assay has not been evaluated with neonate serum specimens or for use with plasma or other specimen types such as urine or cerebrospinal fluid.

 

The assay may exhibit reduced detection of galactomannan in patients with chronic granulomatous disease and Job syndrome.

 

The concomitant use of antifungal therapy in some patients with invasive aspergillosis may result in reduced sensitivity of the assay.

 

False-positive galactomannan results are possible in patients receiving PLASMA-LYTE for intravenous hydration or if PLASMA-LYTE is used for bronchoalveolar lavage.

 

Specimens containing Histoplasma antigen may cross-react in the Aspergillus galactomannan assay.

Supportive Data

In clinical studies submitted for the FDA-approval process, the sensitivity of the test was reported to be 81% for proven/provable invasive aspergillosis (N=31 patients), and the specificity was 89% (N=148 patients). The positive and negative predictive values were reported as 68% and 96% respectively, based on an average prevalence of 14% in the study population. In a low-prevalence population (5%), the positive predictive value decreases to 31%; the negative predictive value remains at 96%.(Package insert: Platelia Aspergillus EIA, Bio-Rad Laboratories; 06/2003)

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

1. Maertens J, Verhaegen J, Lagrou K, Boogaerts M: Screening for circulating galactomannan as a noninvasive diagnostic tool for invasive aspergillosis in prolonged neutropenic patients and stem cell transplantation recipients: a prospective evaluation. Blood. 2001 March 15;97(6):1604-1610

2. Pinel C, Fricker-Hidalgo H, Lebeau B, et al: Detection of circulating Aspergillus fumigatus galactomannan: value and limits of the Platelia test for diagnosing invasive aspergillosis. J Clin Microbiol. 2003 May;41(5):2184-2186

3. Swanink CM, Meis JF, Rijs AJ, Donnelly JP, Verweij PE: Specificity of a sandwich enzyme-linked immunosorbent assay for detecting Aspergillus galactomannan. J Clin Microbiol. 1997 Jan;35(1):257-260

4. Ansorg R, van den Boom R, Rath P: Detection of Aspergillus galactomannan antigen in foods and antibiotics. Mycoses. 1997 Dec;40(9-10):353-357

5. Connolly P, Durkin M, Wheat LJ, et al: Rapid diagnosis of systemic and invasive mycoses. Clinical Microbiology Newsletter 2007 Jan;29(1):1-5

6. Thompson GR, Patterson TF: Aspergillus species. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Elsevier; 2020:3103-3116

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

The Platelia Aspergillus enzyme immunoassay (EIA) is a 1-stage immunoenzymatic sandwich microplate assay that detects galactomannan in human serum. The assay uses the rat monoclonal antibody EBA-2, which is directed against Aspergillus galactomannan. The monoclonal antibody is used 1) to coat the wells of the microplate and bind the antigen and 2) as the detector antibody in the conjugate reagent (peroxidase-linked monoclonal antibody).

 

Serum samples are heat-treated in the presence of EDTA in order to dissociate immune complexes and to precipitate serum proteins that could possibly interfere with the test. The treated serum samples and conjugate are added to the wells coated with the monoclonal antibody and incubated. A monoclonal antibody-galactomannan-monoclonal antibody/peroxidase complex is formed in the presence of Aspergillus antigen.

 

The strips are washed to remove any unbound material, and the substrate solution is added, which will react with the complex bound to the well to form a blue color reaction. The enzyme reaction is stopped by the addition of acid, which changes the blue color to yellow. The optical absorbance of specimens and controls is determined with a spectrophotometer set at 450 nm and 620/630 nm wavelengths.

 

Negative, cutoff (low-positive), and high-positive controls are analyzed each time the assay is performed. The presence or absence of Aspergillus galactomannan antigen in the test sample is determined by calculation of an index for the specimen. The index is the optical density (OD) value of the specimen divided by the mean OD of wells containing the cutoff control serum (low-positive control).(Package insert: Platelia Aspergillus EIA. Bio-Rad Laboratories; 10/2013)

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, 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.

1 to 4 days

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

2 weeks

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 Regional Manager. 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.

87305 

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
ASPAG Aspergillus Ag, S 44357-2
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.
84356 Aspergillus Ag, S 44357-2

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