Aspergillus Galactomannan Antigen
Label Mnemonic: BALGALAC
Epic Lab Code: LAB7740
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
BAL Fluid
Collection Medium:
Sterile container
Minimum:
2 mL BAL (bronc lavage) in sterile container
Turn Around Time:
1 day upon receipt at reference laboratory
Interpretive Data:
A positive result in bronchoalveolar lavage (BAL) fluid supports a Diagnosis of invasive, pulmonary aspergillosis. 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 below).

A Negative results in BAL fluid does not rule out the diagnosis of Invasive Aspergillosis(IA). Patients at risk of IA should be monitored twice a week for Aspergillus antigen levels in serum until determined to be clinically unnecessary.

Aspergillus antigen levels typically decline in response to effective antimicrobial therapy.
Comments:
Useful For: As an aid in the diagnosis of invasive aspergillosis and Antimicrobial therapy.

Cautions:
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 drawn 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's 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.
Methodology:
Enzyme Immunoassay (EIA)
CPT Code:
87305