Hydrophobic Interactions as a Basis for Interfering with Microbial Adhesion

Abstract

Hydrophobic interactions are considered important in a variety of microbial adhesion phenomena in both the open environment, as well as the host (for a review on hydrophobicity in the context of microbial adhesion, see Rosenberg and Doyle, 1990). Examples of medically-related adhesion phenomena that appear to be influenced by hydrophobic interactions include adhesion to teeth, fatty tissues, insect cuticle, catheters, intrauterine contraceptive devices, bioprostheses, contact lenses, and other biomaterials, as well as a variety of epithelial and phagocytic cell types. In 1980, we proposed a simple technique for measuring bacterial (later including eucaryotic microorganisms) adhesion to liquid hydrocarbons based on simply vortexing washed cell suspensions with different test hydrocarbons, with concomitant adhesion at the oil:water interface. The observation that adhesion could be reversed by isopropanol was one indication that hydrophobic interactions were involved, leading us to propose this test as a simple technique for studying cell surface hydrophobicity (Rosenberg et al., 1980). Many tests exist for studying hydrophobic surface properties of microorganisms, including some recently proposed techniques (Lin et al., 1995), but their discussion is beyond the scope of this chapter (for reviews, see Rosenberg and Doyle, 1990; Rosenberg, 1991; Rosenberg et al., 1991a; Van der Mei et al., 1991). The microbial adhesion to hydrocarbon (MATH) test subsequently led us into various avenues of investigation related to identification of cell surface components which promote or interfere with adhesion at the oil:water interface, as well as soluble agents which inhibit or promote adhesion. Furthermore, the observation that many oral microorganisms adhere at the oil:water interface led us to develop a novel two-phase microbe-desorbing mouthrinse, which has been sold successfully in Israel since 1992.