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Test ID PLFA Cryptococcus Antigen Screen, Lateral Flow Assay, Pleural Fluid


Additional Testing Requirements


Pleural fluid testing for cryptococcal antigen should also be submitted for routine fungal culture. Order FGEN / Fungal Culture, Routine.



Specimen Required


Container/Tube: Sterile vial

Specimen Volume: 0.5 mL


Useful For

Diagnosis of infection with Cryptococcus species

Highlights

This test can be used as an adjunct for diagnosis of pulmonary infection with Cryptococcus species. Positive results are indicative of infection; however, cryptococcal antigen may remain detectable for prolonged periods of time following disease resolution.

Disease States

  • Cryptococcosis

Testing Algorithm

If this screen is positive, the antigen titer will be performed at an additional charge.

Method Name

Lateral Flow Assay (LFA)

Reporting Name

Cryptococcus Ag Screen, LFA, PF

Specimen Type

Pleural Fluid

Specimen Minimum Volume

0.25

Specimen Stability Information

Specimen Type Temperature Time Special Container
Pleural Fluid Refrigerated (preferred) 21 days
  Frozen  30 days

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Clinical Information

Cryptococcosis is an invasive fungal infection caused by Cryptococcus neoformans or Cryptococcus gattii. C neoformans has been isolated from several sites in nature, particularly weathered pigeon droppings. C gattii was previously associated with tropical and subtropical regions only; however, more recently this organism has also been found to be endemic in British Columbia, along the Pacific Northwest, and in the Southeastern United States.

 

Infection is usually acquired via the pulmonary route. Patients are often unaware of any exposure history. Approximately half of the patients with symptomatic disease have a predisposing immunosuppressive condition such as AIDS, steroid therapy, lymphoma, or sarcoidosis. Symptoms may include fever, headache, dizziness, ataxia, somnolence, and cough. While the majority of C neoformans infections occur in immunocompromised patient populations, C gattii has a higher predilection for infection of healthy individuals.

 

In addition to the lungs, cryptococcal infections frequently involve the central nervous system (CNS), particularly in patients infected with HIV. Mortality among patients with CNS cryptococcosis may approach 25% despite antibiotic therapy. Untreated CNS cryptococcosis is invariably fatal. Disseminated disease may affect any organ system and usually occurs in immunosuppressed individuals.

Reference Values

Negative

Interpretation

The presence of cryptococcal antigen in pleural fluid is indicative of infection with Cryptococcus species.

 

Monitoring cryptococcal antigen levels as a means to determine response to therapy is discouraged, as antigen levels may persist despite adequate treatment and disease resolution.

 

A negative result indicates lack of infection; however, rare cases of false-negative results have been reported. Fungal culture should always be ordered alongside antigen testing.

Cautions

A negative result does not preclude diagnosis of cryptococcal infection, particularly if the patient is at risk for cryptococcosis and shows symptoms consistent with this disease.

 

False-positive results may occur in patients with trichosporonosis or infection with Capnocytophaga species.

Clinical Reference

1. Binnicker MJ, Jespersen DJ, Bestrom JE, Rollins LO: Comparison of four assays for the detection of cryptococcal antigen. Clin Vaccine Immunol. 2012 Dec;19(12):1988-1990

2. Howell SA, Hazen KC, Brandt ME: Candida, cryptococcus, and other yeast of medical importance. In: Manual of Clinical Microbiology. 11th ed. ASM Press; 2015:1984-2014

Method Description

The Cryptococcus antigen (CrAg) lateral flow assay is a sandwich immunochromatographic assay. Specimens and diluent are added to a test tube and the lateral flow device is added. The test uses specimen wicking to capture gold-conjugated, anti-cryptococcal antigen monoclonal antibodies and gold-conjugated control antibodies deposited on the test membrane. If cryptococcal antigen is present in the specimen, it binds to the gold-conjugated anti-cryptococcal antigen antibodies. This complex wicks up the membrane and interacts with the test line, which has immobilized anti-cryptococcal antigen monoclonal antibodies. The antigen-antibody complex forms a sandwich at the test line causing a visible line to form. A valid test shows a visible line at the control line. Positive test results create 2 lines (control and specimen), while negative results form only the control line.(Package insert: CrAg Lateral Flow Assay. IMMY; Rev 06/27/2019)

Day(s) Performed

Monday through Sunday

Report Available

Same day/1 to 2 days

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

87899-Cryptococcus Ag Screen, LFA, PF

87899-Cryptococcus Ag Titer, LFA, PF (if appropriate)

NY State Approved

Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
PLFAT Cryptococcus Ag Titer, LFA, PF No No

Forms

If not ordering electronically, complete, print, and send Infectious Disease Serology Test Request (T916) with the specimen.