Lack of sialidase activity in Candida albicans and Candida glabrata

Because several micro-organisms having close contact to animal hosts and ma n produce sialidase (EC 3.2.1.18) as a tool for adhesion and invasion, we i nvestigated two Candida species for the presence of this enzyme. Two sensit ive assays, a fluorometric test with 4-methylumbelliferyl-alpha-D-N-acetyln euraminic acid and a radiometric test with H-3-labelled sialyllactitol as s ialidase substrates, were applied to detect sialidase activity. None of 40 Candida albicans and 10 C. glabrata strains grown in three different media exhibited sialidase activity, but the positive control Ophiostoma stenocera s produced sialidase under comparable conditions. Our surprising negative f indings are divergent from an earlier positive report, which may be due to strain selection or bacterial contamination. These results indicate that si alidase is probably of no relevance in cutaneous or mucosal candidoses.