Fungal Serology-Introduction, List of Tests, Application, and Keynotes

Introduction

Fungal serology detects antibodies and antigens from fungal pathogens in blood samples. Moreover, it identifies immune responses to various mycoses. Additionally, clinicians use these tests for diagnosing invasive fungal infections. Furthermore, serology supplements culture and microscopic techniques. Consequently, it plays a vital role in clinical diagnosis.

List of Tests

Immunodiffusion tests detect precipitating antibodies against fungi. Moreover, complement fixation tests measure antibody levels to fungal antigens. Additionally, enzyme immunoassays quantify specific fungal antibodies accurately. Furthermore, latex agglutination tests provide rapid qualitative results. Also, counterimmunoelectrophoresis identifies fungal antigens in serum reliably. The list of common tests is as follows-

1. Galactomannan assay
2. Beta D glucan assay
3. Candida Mannan antigen
4. Candida Anti-mannan antibody
5. IgE and IgG specific for Aspergillus
6. Histoplasma antigen
7. CALAS/ Lateral flow immunoassay for Cryptococcus

Application

Clinicians use fungal serology to diagnose systemic mycoses. Moreover, the tests assist in monitoring treatment response. Additionally, serology assesses immune status in immunocompromised patients. Furthermore, it supports epidemiological studies in endemic areas. Consequently, it improves patient management and outcomes.

Keynotes

• Fungal serology offers rapid, noninvasive diagnosis.
• Moreover, it enhances detection when cultures are slow or negative.
• Additionally, test accuracy depends on timing and the patient’s immune status.
• Furthermore, serological results complement imaging and histopathology findings.
• Ultimately, fungal serology guides targeted antifungal therapy effectively.

Galactomannan Assay

• The assay detects galactomannan, a polysaccharide from Aspergillus cell walls.
• Moreover, it employs enzyme immunoassays to quantify antigen levels.
• Furthermore, the test aids in diagnosing invasive aspergillosis.
• Consequently, clinicians use it in immunocompromised patients.

Beta-D Glucan Assay

• The assay measures beta-D glucan from fungal cell walls.
• Additionally, it uses colorimetric methods for detection.
• Furthermore, the test screens for invasive fungal infections broadly.
• However, it does not detect Cryptococcus or Zygomycetes.
• Consequently, clinicians combine it with other assays for complete evaluation.

Candida Mannan Antigen

• The test detects mannan antigen released by Candida species.
• Moreover, it employs enzyme immunoassays for measurement.
• Furthermore, it indicates the presence of active Candida infection.
• Consequently, early diagnosis of candidiasis becomes possible.

Candida Anti-Mannan Antibody

• The assay measures antibodies directed against Candida mannan.
• Additionally, it uses ELISA methods to quantify antibody titers.
• Furthermore, it reflects the immune response to Candida infection.
• Consequently, it assists in diagnosing invasive candidiasis.

IgE and IgG Specific for Aspergillus

• The tests measure IgE and IgG antibodies against Aspergillus antigens.
• Moreover, they use immunoassays to quantify these antibody levels.
• Additionally, IgE levels indicate allergic bronchopulmonary aspergillosis.
• Furthermore, IgG levels suggest chronic or invasive aspergillosis.
• Consequently, they help differentiate Aspergillus-related disorders.

Histoplasma Antigen

• The assay detects antigens from Histoplasma capsulatum in serum or urine.
• Moreover, it employs enzyme immunoassays for rapid detection.
• Furthermore, the test aids in diagnosing histoplasmosis.
• Consequently, clinicians diagnose disseminated histoplasmosis promptly.

CALAS/Lateral Flow Immunoassay for Cryptococcus

• Cryptococcal Antigen Latex Agglutination System (CALAS) detects Cryptococcus antigen in cerebrospinal fluid.
• Additionally, it uses latex agglutination for antigen identification.
• Furthermore, lateral flow assays provide rapid, point-of-care results.
• Consequently, these tests enable early detection of cryptococcal meningitis.

Further Readings

1. https://academic.oup.com/book/41270/chapter/351217461
2. https://www.aiimsbhopal.edu.in/iMARC/pdfs/Fungal_Serology_Workshop_SOP.pdf
3. https://www.synnovis.co.uk/our-tests/fungal-serology
4. https://www.publichealthontario.ca/-/media/documents/lab/lab-sd-134-fungal-serology.pdf?la=en
5. https://pmc.ncbi.nlm.nih.gov/articles/PMC10099008/
6. https://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(21)00080-X/pdf
7. https://pubmed.ncbi.nlm.nih.gov/37360856/
8. https://www.healthcare.uiowa.edu/path_handbook/handbook/test94.html