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Published on: July 18, 2012
Diagnosis of invasive candidiasis by a dot immunobinding assay for Candida antigen detection
1Department of Medicine, Hahnemann University, Philadelphia, Pennsylvania 19102.
Insights
A new dot immunobinding assay accurately detects Candida antigens in patient serum, aiding in the diagnosis of invasive candidiasis. This rapid test shows high sensitivity and specificity for identifying fungal infections.
Area of Science:
- Immunology
- Medical Mycology
- Clinical Diagnostics
Background:
- Invasive candidiasis poses a significant threat, particularly to immunocompromised patients.
- Early and accurate diagnosis of candidemia is crucial for effective treatment and improved patient outcomes.
- Current diagnostic methods for invasive fungal infections can be slow or lack sensitivity.
Purpose of the Study:
- To describe a novel dot immunobinding assay for detecting Candida cytoplasmic antigens.
- To evaluate the sensitivity, specificity, and predictive values of this assay in various patient groups.
- To assess the utility of the assay in identifying invasive candidiasis.
Main Methods:
- Development of a dot immunobinding assay using rabbit anti-Candida immunoglobulin G and gold-conjugated goat anti-rabbit immunoglobulin G.
- Detection of Candida cytoplasmic antigens in buffer and human serum.
- Assay of serial serum samples from patients with candidemia, high-risk for candidiasis, other deep mycoses, and low-risk hospitalized patients.
Main Results:
- The assay detected as little as 1 ng/ml of Candida protein in buffer and 10 ng/ml in human serum.
- Antigenemia was detected in 16 of 19 patients with invasive candidiasis (84.2% sensitivity).
- Overall specificity was 94.4%, with a positive predictive value of 80% and negative predictive value of 95.7%.
Conclusions:
- The described dot immunobinding assay is a rapid and accurate method for detecting Candida antigens.
- The assay demonstrates significant potential for identifying patients with invasive candidiasis.
- This diagnostic tool could improve the timely management of fungal infections.
Abstract:
A dot immunobinding assay which uses a polyclonal rabbit anti-Candida immunoglobulin G as the primary antibody and colloidal gold coated with goat anti-rabbit immunoglobulin G as the secondary antibody for the detection of Candida cytoplasmic antigens is described. It was able to detect as little as 1 ng of total Candida protein per ml when a cytoplasmic extract of Candida albicans was seeded into buffer and 10 ng/ml when the same extract was seeded into pooled human serum. Serial serum samples from four groups of patients were assayed for Candida antigen: (i) 22 patients with candidemia, (ii) 16 patients at high risk for invasive candidiasis, (iii) 3 patients with other deep mycoses, and (iv) 50 hospitalized patients at low risk for serious Candida infection. Of the 22 candidemic patients, 19 had invasive candidiasis and 3 had transient candidemia. Antigenemia was detected in 16 of the 19 patients with invasive candidiasis (including patients with C. albicans, Candida tropicalis, Candida glabrata, Candida krusei, and Candida parapsilosis) and in 4 of 16 patients at high risk for invasive candidiasis. There was no detectable antigen in 12 high-risk control patients, 3 patients with transient candidemia, 3 patients with other deep mycoses, and 50 relatively low-risk patients. The sensitivity for detecting invasive disease in candidemic patients and specificity for all patients studied were 84.2 and 94.4%, respectively. The positive predictive value was 80%; the negative predictive value was 95.7%. The sensitivity for neutropenic patients with invasive disease was 85.7%. This assay is rapid and accurate and appears to be useful in identifying candidemic patients with invasive candidiasis.
