The role of bacterial hydrophobicity in infection: bacterial adhesion and phagocytic ingestion

Abstract

The role that bacterial surface hydrophobicity (surface tension) plays in determining the extent of adhesion of polymer substrates and phagocytic ingestion is reviewed. The early attachment phase in bacterial adhesion is shown to depend critically on the relative surface tensions of the three interacting phases; i.e., bacteria, substrate, and suspending liquid surface tension. When suspended in a liquid with a high surface tension such as Hanks balanced salt solution, the most hydrophobic bacteria adhere to all surfaces to the greatest extent. When the liquid surface tension (γLV) is larger than the bacterial surface tension (γBV), then for any single bacterial species the extent of adhesion decreases with increasing substrate surface tension (γSV). When γLV < γBV then adhesion increases with increasing γSV. Bacterial surface tension also determines in part the extent of phagocytic ingestion and the degree to which antibodies aspecifically adsorb onto the bacterium resulting in opsonization. The nonspecific adsorption of antibodies results in a considerable modification in the surface properties of the bacteria. Bacterial surface hydrophobicity can be altered significantly through exposure to subinhibitory concentrations of antibiotics, surfactants, lectins, etc. The effect of these changes on subsequent phagocytic ingestion is discussed.