Cross-reactivity of cryptococcal antigen lateral flow assay with basidiomycetous yeasts

The cryptococcal antigen lateral flow assay (CrAg LFA) is a widely available point-of-care test for the diagnosis of cryptococcal meningitis. Although there have been some reports of cross-reactivity with Trichosporon species, the extent of cross-reactivity among basidiomycetous yeasts has not been widely explored. We tested a range of basidiomycete yeast isolates using a CrAg LFA to examine potential cross-reactivity, with positive results for all isolates belonging to Trichosporon and Naganishia species, and for some isolates of Cutaneotrichosporon, Filobasidium and Ustilago species. While these species rarely cause invasive infection, the potential for cryptococcal antigen cross-reactivity should be considered.