Superficial fungal infections, including oral thrush, often affect aged full denture wearers and many individuals over 65 years old.The aim of this study was to examine the ultrastructural morphology of a very rare yeast, named Hanseniaspora uvarum / guillermondi, member of the Ascomycetes family, whose pathogenesis and behaviour is not widely known.The yeast was isolated from whitish lesions of the buccal mucosa of an 70 years old woman. The specimen was collected with a mouth swab and cultured in Sabourauds-Dextrose agar.The identification of the organism was performed on the Api 20C Aux System.The yeast colonies, after fixation in glutaraldehyde 3% for 1 hour were immersed in OsO4 1% solution for 1 hour and were «in tissue» stained with uranyl acetate. Ultrathin sections, were observed with TEM Jeol Cx100.Our ultrastructural observations showed that this yeast had a thick cell wall in which the outer surface appeared fuzzy. In some yeasts we observed multilayered intracytoplasmic membrane a figure which is not described as far as we know in any yeast. Many vacuoles were frequently observed in the cytoplasm and especially in the center of the oval shaped cells.Bilateral budding which form ascospores is identical for the morphology of this yeast.

Le but de ce travail était la recherche de la morphologie ultrastructurale du «Hanseniaspora uvarum/guillermondi» qui appartient à la famille des Ascomycètes et dont la pathogénèse n’est pas bien connue.Le microorganisme a été isolé dans des lésions blanches de la muqueuse buccale d’une femme âgée de 70 ans.Le matériel d’étude a été mis en culture dans des boîtes de Pétri contenant un milieu de Sabouraud dextrose agar. L’identification de «Hanseniaspora uvarum» a été effectuée par le système Api 20C Aux.Les colonies après fixation dans de la glutaraldéhyde 3 % et postfixation au OsO4 1%, ont été traitées selon la technique conventionnelle pour la microscopie électronique.L’étude ultrastructurale a montré un microorganisme présentant une paroi cellulaire épaisse dont la surface externe paraissait dentelée). Des membranes multilamellaires ainsi que plusieurs vacuoles ont été observées dans le cytoplasme du Hanseniaspora Uvarum/guillermondi.