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Test ID: ASPAG Aspergillus (Galactomannan) Antigen, Serum

Reporting Name

Aspergillus Ag, S

Useful For

Aiding in the diagnosis of invasive aspergillosis

 

Assessing response to therapy

Clinical Information

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); and 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.

Interpretation

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.

Analytic Time

1 day

Day(s) and Time(s) Performed

Monday; 4 p.m.

Tuesday through Friday; 9 a.m. and 4 p.m.

Sunday; 8 a.m.

Clinical Reference

1. Maertens J, Verhaegen J, Lagrou K, et al: 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, et al: 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

Method Name

Enzyme Immunoassay (EIA)

Specimen Type

Serum SST


Specimen Required


Container/Tube: Serum gel

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 collection SST tube. Do not aliquot or open tube.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum SST Refrigerated (preferred) 14 days SERUM GEL TUBE
  Frozen  14 days SERUM GEL TUBE

Reference Values

<0.5 index

Reference values apply to all ages.

Test Classification

This test has been cleared or approved by the U.S. 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

87305 

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ASPAG Aspergillus Ag, S 44357-2

 

Result ID Test Result Name Result LOINC Value
84356 Aspergillus Ag, S 44357-2
Mayo Clinic Laboratories | Neurology Catalog Additional Information:

mml-CNS-Infections, mml-Pediatric