ADHESIVE INTERACTIONS BETWEEN MEDICALLY IMPORTANT YEASTS AND BACTERIA

Yeasts are being increasingly identified as important organisms in hum an infections. Adhesive interactions between yeasts and bacteria may c ontribute to yeast retention al body sites. Methods for studying adhes ive interactions between bacterial strains are well known, and range f rom simple macroscopic methods to flow chamber systems with complex im age analysis capabilities. The adhesive interactions between bacteria and yeasts have been studied employing several of the methods original ly developed for studying adhesive interactions between bacteria. Howe ver, in many of the methods employed the larger size of the yeasts as compared with bacteria results in strong sedimentation of the yeasts, often invalidating the method adapted. In addition, most methods are s emi-quantitative and do not properly control mass transport. Consequen tly, adhesive interaction mechanisms between yeasts and bacteria ident ified hitherto, including lectin binding and protein-protein interacti ons, must be regarded with caution. Extensive physico-chemical charact eristics of yeast cell surfaces are not available and a physico-chemic al mechanism has not yet been put forth. A new method for quantifying adhesive interactions between yeasts and bacteria is proposed, based o n the use of a parallel plate flow chamber, in which the influence of adhering bacteria upon the kinetics of yeast adhesion and aggregation of the adhering yeasts is quantitatively evaluated, under carefully co ntrolled mass transport. (C) 1998 Federation of European Microbiologic al Societies. Published by Elsevier Science B.V.