SIALIDASE IS NOT PRODUCED BY DERMATOPHYTE S IN-VITRO

Sialidase (EC 3.2.1.18) is a pathogenicity factor of many microorganis ms, and may also play a role in adhesion of dermatophytes to the epith elia of their hosts by the hydrolytical cleavage of terminal, negative ly charged sialic acids of glycoconjugates on the cell surfaces, thus allowing fungal lectins to bind to the subterminal sugars. Therefore, 116 strains of seven species of dermatophytes were investigated for si alidase production. Two highly sensitive, quantitative sialidase assay s were applied to cell homogenates and culture supernatants from seven different media of the fungi, but were always negative for sialidase activity. However, sialidase activity was always detected in Ophiostom a stenoceras used as a positive control cultivated in parallel; the en zyme was inducable by sialylated mucins. A sialidase-dependent pathome chanism for dermatophytes appears unlikely based on the results presen ted.