Antigènes fongiques en réanimation : tests disponibles et état des lieux

Numerous serological assays try to supply the pitfalls of microbiological diagnostic methods for fungal infections. Several antigens have been assessed: the galactomannan (GM), the mannan (Mn), the β-glucan (ßG), and the capsular antigen for the diagnosis of invasive aspergillosis, yeast infections, all the fungal infections, and the Cryptococcus neoformans infection respectively. The performance characteristics of these assays are usually satisfactory when serum samples collected in well defined clinical settings are used. In contrast, the results of prospective studies are often disappointing. This underlines the difficulty in standardizing the patient populations and the definitions of fungal infections. For the GM assay, the conclusions obtained in onco-hematology can be used for immunocompromised patients hospitalized in intensive care units. For the Mn assays, the hope relies on the simultaneous detection of both antigen and antibodies. The advantage over the microbiological screening for yeasts of different anatomical sites remains to be demonstrated. For the βG assay, its best interest seems to be its negative predictive value as bacterial and fungal infections are hardly distinguished when the test is positive. Excepted for the capsular cryptococcal antigen, a single test is usually not contributive for any of the assays, which should be implemented as a screening test for patients at risk for fungal infections.