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Comparison of coccidioidal complement fixation and quantitative immunodiffusion serology at a reference laboratory
Allen W Bryan1,2, Jane Sykes3, Kelly Crucillo2
1University of California, Davis, Department of Medical Microbiology and Immunology, Davis, CA, USA.
Insights
Coccidioidomycosis diagnosis relies on immunodiffusion and complement fixation (CF) tests. These two methods for detecting IgG antibodies show high concordance, suggesting they are interchangeable for coccidioidomycosis diagnosis.
Area of Science:
- Medical Mycology
- Clinical Diagnostics
- Immunoserology
Background:
- Coccidioidomycosis incidence is rising, necessitating reliable diagnostic methods.
- Current non-invasive diagnostics include immunodiffusion and complement fixation (CF) testing.
- Complement fixation (CF) testing is considered the gold standard for coccidioidomycosis diagnosis.
Purpose of the Study:
- To directly compare quantitative immunodiffusion and complement fixation (CF) testing for IgG antibodies.
- To assess the concordance between immunodiffusion and CF tests in diagnosing coccidioidomycosis.
- To determine the interchangeability of these diagnostic methods in a reference laboratory.
Main Methods:
- Comparative analysis of 368 patient samples.
- Quantitative immunodiffusion assay for IgG antibodies.
- Complement fixation (CF) assay for IgG antibodies.
Main Results:
- A high concordance rate of 97.8% (360/368 samples) was observed between the two methods.
- Statistical analysis showed a P-value < .001, indicating a highly significant agreement.
- Both immunodiffusion and CF tests demonstrated strong agreement in detecting IgG antibodies.
Conclusions:
- Quantitative immunodiffusion and complement fixation (CF) testing for IgG antibodies are highly concordant.
- These diagnostic tests can be considered interchangeable in reference laboratory settings for coccidioidomycosis.
- The findings support the use of either method for reliable coccidioidomycosis diagnosis.
Abstract:
The incidence of coccidioidomycosis continues to increase. The diagnosis frequently relies on non-invasive diagnostic testing with immunodiffusion and complement fixation (CF) testing the current gold standard. A direct comparison of quantitative immunodiffusion and CF for IgG antibodies has not been previously reported. In a comparison of 368 samples, there was close concordance observed (360/368 = 97.8%) (P-value < .001). These tests can be considerably interchangeable in the reference laboratory setting.
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