Evaluation of a newly developed down-flow immunoassay for detection of serum mannan antigens in patients with candidaemia

Abstract

A down-flow immunoassay has been developed to detect serum mannan antigens, and the test was recently marketed as the Unimedi Candida monotest. Using 251 serum samples from 105 patients with candidaemia, a comparison of the Unimedi Candida monotest with the Cand-Tec latex agglutination test and 2 microplate enzyme immunoassay tests (Platelia Candida Ag test and Unimedi Candida) was conducted. One hundred and seventy-five febrile patients without clinical and microbiological evidence of fungal infections and pneumocytosis were examined as controls. The Cand-Tec test had a sensitivity of 38% and a specificity of 82%. The sensitivity and specificity of the Platelia Candida Ag test, the Unimedi Candida and the Unimedi Candida monotest were 53 and 92%, 69 and 89% and 82 and 96%, respectively. The sensitivity of the Unimedi Candida monotest was significantly (P<0.01) higher than that of the Plateria Candida Ag test for diagnosing candidaemia caused by Candida parapsilosis. The beta-D-glucan assay had a high sensitivity of 95%, with a specificity of 84%. Of 74 patients with candidaemia whose sera were available before or on positive blood culture sampling, 29 (39%), 38 (51%) and 48 (65%) patients had antigenemia detected using the Platelia Candida Ag test, the Unimedi Candida and the Unimedi Candida monotest, respectively. The Unimedi Candida monotest seems to be a promising tool for the early diagnosis of invasive candidiasis, because the test was sensitive, simple, rapid (approx. 1 h) and cost-effective.