Fungal – Serology

Timing of Specimen Collection

An acute serum (collected early after the onset of symptoms) and a convalescent (collected 2-3 weeks later) may be required for laboratory diagnosis. Please see “Limitations of the Procedure” below, under Additional Information.

Limitations

Haemolysed, icteric, lipemic or microbially contaminated sera or plasma are not recommended for testing.

Storage and Transport

Label the specimen container with the patient’s full name, date of collection and one other unique identifier such as the patient’s date of birth or Health Card Number. Failure to provide this information may result in rejection or testing delay.

Special Instructions

Centrifuge if using SST. Place specimen in biohazard bag and seal.

Test Frequency and Turnaround Time (TAT)

Aspergillus EIA is performed biweekly.
TAT for Aspergillus is up to 14 days after receipt at test site.

Histoplasma, Blastomyces and Coccidioides testing is performed once per week.
TAT for Histoplasma, Blastomyces and Coccidioides serology is up to 10 days after receipt at test site.

Aspergillus is tested by Enzyme Immunoassay (EIA) and detects IgG antibodies. Results will be reported as “Non-Reactive”, “Indeterminate”, or “Reactive”. This test may be useful in the diagnosis and monitoring of immunocompetent, adult patients where allergic bronchopulmonary aspergillosis (ABPA), chronic pulmonary aspergillosis (CPA), or fungal sinusitis are due to Aspergillus.

Histoplasma is tested by Immunodiffusion and detects M and H band precipitins. Hisptoplasma capsulatum serology results will be reported as “Non-Reactive”, “Partial” or “Reactive”. Reactive results will indicate presence of M or H bands (precipitins), or both M and H bands. M band is indicative of recent/acute infection, as well as those who have recently recovered from histoplasmosis. H bands appear later and less frequently than M bands, and rarely in the absence of M bands. Bands may be reported as partial which is an indeterminate result.

Blastomyces is tested by Immunodiffusion and detects A band precipitins. Blastomyces dermatitidis serology results will be reported as “Non-Reactive”, “Partial” or “Reactive”. Reactive results will indicate presence of A band (precipitins). The A band may be reported as partial band which is an indeterminate result. Reactive A band provides presumptive evidence of infection.

Coccidioides is screened by EIA which detects IgM (against TP antigens) and IgG (against CF antigens). Results will be reported as “Non-Reactive”, “Indeterminate” or “Reactive”. Samples which are reactive for IgG or IgM will be further tested by Immunodiffusion.

Coccidioides is confirmed by Immunodiffusion and detects ID-TP and ID-CF band precipitins. Coccidioides immititis Immunodiffusion results will be reported for both ID-TP and ID-CF bands (precipitins) as “Non-Reactive”, “Partial” or “Reactive”. Formation of ID-TP bands is evidence of acute or recent infection. Formation of ID-CF bands is evidence of recent past or chronic Coccidioides infection. ID-TP and ID-CF bands may be reported as partial bands; this should be interpreted as an inconclusive result.

For all of these fungi, a negative result does not rule out the possibility of current infection.

Reporting

Results are reported to the ordering physician or health care provider as indicated on the requisition.

References

LAB-SD-008, Blood Collection using Serum Separator Tubes

LAB-SD-134, Fungal Serology Update - Test algorithms and methodologies