Fungal Antibody Determination
ANALYTES TESTED: Histoplasma capsulatum, Blastomyces dermatitidis and Coccidioides immitis antibodies.
USE OF TEST: To obtain serologic evidence of an immune response (recent or past antibody production) to Histoplasma capsulatum, Blastomyces dermatitidis, or Coccidioides immitis by utilizing complement fixation (CF) and immunodiffusion (ID) test methods.
SPECIMEN COLLECTION AND SUBMISSION GUIDELINES:
Test Request Form DCH-0583
Specimen Submission Guidelines
Serum Specimen Collection DCH-0811
Transport Temperature: Frozen, wet ice or ambient temperature
Acceptable specimens for CF testing: Serum, cerebrospinal fluid and sterile body fluids (i.e., thoracentesis, pleural, joint fluid).
Acceptable specimens for fungal ID testing: Serum only.
Minimum Acceptable Volume: 1-3 ml
Container: 3 or 5 ml plastic tube with skirted cap.
Shipping Unit: Unit 8
SPECIMEN REJECTION CRITERIA:
Specimens lacking two unique patient identifiers (i.e., full name, date of birth) will not be tested.
Contaminated, grossly hemolyzed or chylous specimens are unacceptable for testing and will be reported as Unsatisfactory.
Methodology: Complement fixation and fungal immunodiffusion
Turn Around Time: One to three weeks.
Where/When Performed: Lansing/Wednesday through Friday.
Histoplasma mycelia phase – NON-REACTIVE at 1:8 dilution
Histoplasma yeast phase – NON-REACTIVE at 1:8 dilution
Blastomyces – NON-REACTIVE at 1:8 dilution
Coccidioides – NON-REACTIVE at 1:2 dilution
Histoplasmosis: A complement fixation (CF) titer of ≥ 1:32 is considered clinically significant; however, some patients with active disease may exhibit titers of 1:8 or 1:16. A four-fold or greater difference between acute and convalescent specimens collected 14-21 days apart may indicate dissemination. Cross-reactivity frequently occurs with B.dermatitidis. In immunodiffusion testing, the “M” band is the first to appear in acute pulmonary disease and frequently appears without the “H” band. The “M” band is more commonly detected and may persist for 3 years after recovery. The “M” band may be present in persons recovering from the disease or in cases of early infection while an “H” band corresponds with active infection, may represent extrapulmonary dissemination, and is usually only present for 4-6 weeks after exposure. Antibody may be detected by CF when immunodiffusion is negative.
Blastomycosis: Cross-reactions with histoplasmin and coccidioidin antibodies occur frequently during early stages of the disease. A CF titer is detected less than 50% of the time when active disease is present. Antibody may be detected by immunodiffusion when the CF is negative. A titer of ≥1:8 is considered clinically significant. Fungal immunodiffusion is automatically performed when Blastomyces testing is specifically indicated on the test requisition form.
Coccidioidomycosis: The CF test has both diagnostic and prognostic value and will be positive in 90% of symptomatic cases of the disease. A persistently rising titer combined with clinical symptoms may indicate dissemination. Antibodies detected by immunodiffusion will appear at approximately the same time as CF antibodies and are formed in response to the same antigen. A titer of ≥ 1:2 is considered clinically significant.
In the presence of a high titer reaction against one fungal pathogen, other low level antibody titers may represent cross-reacting antibodies and are not considered significant.
It is recommended that analysis of paired sera be used to diagnose disease. A four-fold or greater rise in titer between acute and convalescent paired specimens, collected 14-21 days apart is consistent with the diagnosis of recent infection.
Routine fungal antibody testing is performed by the complement fixation method. Immunodiffusion testing will be performed if specifically requested by the submitter, to resolve questions of cross-reactivity, if the specimen exhibits anti-complementary activity, and on all CF reactive specimens.
CF testing detects IgM and IgG antibodies only.
Complement fixation = comp. fix, fungal antibody
Fungal immunodiffusion = fungal ID’s, fungal precipitins