Biomarkers for the diagnosis of invasive candidiasis in immunocompetent and immunocompromised patients

Blood culture methods show low sensitivity, so reliable non–culture diagnostic tests are needed to help clinicians with the introduction, de-escalation, and discontinuation of antifungal therapy in patients with suspected invasive candidiasis (IC). We evaluated different biomarkers for the diagnosis of IC in immunocompetent and immunocompromised patients at risk for developing invasive fungal diseases. The specificity of Candida albicans germ-tube antibodies (CAGTA) detection was high (89%−100%), but sensitivity did not exceed 61% even after raising the cut-off from 1/160 to 1/80. We developed enzyme-linked immunoassays detecting antibodies against C. albicans proteins (Als3-N, Hwp1-N, or Met6) that resulted more sensitive (66%−92%) but less specific than CAGTA assay. The combination of 1,3-beta-D-glucan (BDG) detection and CAGTA results provided the highest diagnostic usefulness in immunocompetent patients. However, in immunocompromised patients, anti–Met6 antibodies was the best biomarker, both, alone or in combination with BDG.