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Published on: February 15, 2011
Variability in commercial histoplasma complement fixation antigens
D S Leland1, S E Zimmerman, E B Cunningham
1Indiana University Medical Center, Indianapolis 46202-5200.
Insights
Immuno-Mycologics (IMMY) antigens showed higher reactivity for detecting histoplasma antibodies compared to Meridian Diagnostics antigens. IMMY antigens identified more positive cases, especially in confirmed histoplasmosis patients.
Area of Science:
- Medical Microbiology
- Immunology
- Infectious Diseases
Background:
- Histoplasmosis diagnosis relies on serological tests.
- Antigen performance can vary between manufacturers.
- Accurate detection of histoplasma antibodies is crucial for timely treatment.
Purpose of the Study:
- To compare the reactivity of Immuno-Mycologics (IMMY) and Meridian Diagnostics histoplasmal antibody complement fixation test antigens.
- To evaluate the diagnostic performance of IMMY antigens against Meridian antigens.
Main Methods:
- Retesting 1,386 samples using IMMY histoplasmal yeast (HY) and mycelial (HM) antibody complement fixation test antigens.
- Comparing IMMY results with initial results obtained using Meridian Diagnostics antigens.
- Analyzing discrepancies in antibody titers and identifying false negatives.
Main Results:
- IMMY detected histoplasma antibody (≥1:16) in 20% of HY and 5% of HM samples with low Meridian titers (<1:8).
- IMMY titers were ≥4-fold higher than Meridian titers in 39% of HY and 54% of HM samples with high initial titers (≥1:8).
- 52% of confirmed histoplasmosis cases were negative with Meridian antigens but positive with IMMY antigens.
Conclusions:
- Meridian Diagnostics antigens demonstrated lower reactivity with human histoplasmal antibody.
- IMMY antigens offer improved sensitivity for histoplasma antibody detection.
- Re-evaluation of diagnostic assays is important for accurate histoplasmosis diagnosis.
Abstract:
Using Immuno-Mycologics (IMMY; Norman, Okla.) histoplasmal yeast (HY) and mycelial (HM) antibody complement fixation test antigens, we retested 1,386 samples that were initially tested with Meridian Diagnostics, Inc. (Cincinnati, Ohio), antigens. Histoplasma antibody was identified (greater than or equal to 1:16) in 20% of HY and 5% of HM samples reported to have titers of less than 1:8 with Meridian reagents. IMMY titers were at least fourfold higher than Meridian titers in 39% of HY and 54% of HM samples that initially had titers of greater than or equal to 1:8 with Meridian antigens. Because 30 of 58 (52%) samples from confirmed cases of histoplasmosis yielded negative results with Meridian antigens and positive results upon retesting with IMMY antigens, we concluded that the Meridian antigens had less reactivity with human histoplasmal antibody.
