Trichosporon beigelii is an emerging fungal pathogen, which is morphologically characterized by blastoconidia, arthroconidia and hyphae. The non-hyphal forms of T. beigelii germinate to form hyphae in plasma in vitro and in tissues in vivo, suggesting possible pathophysiological significance of this process. Little is known, however, about the mechanisms of germination of T. beigelii. We therefore studied relevant biochemical and pharmacological factors that may regulate germination of T. beigelii. Germination was significantly enhanced by temperature at 37 degrees C, chemically defined cell culture media such as RPMI-1640, plasma, physiological pH, N-acetylglucosamine and proline. N-acetylglucosamine was equivalent to proline in inducing germination. Germination was suppressed by high concentrations of glucose, increasing inocula, low pH, and amphotericin B at achievable serum concentrations. Thus, many of the factors regulating germination of T. beigelii appear to be similar to those for Candida albicans.