Effect of MV-II-065 on The Phagocytosis of Staphylococcus aureus

Abstract

Staphylococcus aureus is a major source of many clinical problems and is associated with an increase in the cost of health care. The bacteria's ability to be resistant to antibiotics remains ever constant. S. aureus' cell wall is composed of a capsule that hinders the human body's immune system by preventing phagocytosis of the bacteria. The ineffectiveness of antibiotics and the body's immune system creates the need for alternative methods of treatment for S. aureus infections. A potential alternative form of treatment involves the use of mimetics, modified capsular carbohydrates. The goal of these studies was to test the ability of a mimetic, MV-II-065, to block the synthesis of S. aureus capsule. To ascertain the effectiveness of the mimetics, they were administered in different concentrations and incubated with S. aureus overnight. A decrease in capsule production (26% of solvent control) was indicated by decreased binding of monoclonal antibodies to the bacteria during an ELISA assay. Results of phagocytosis assays were variable, however the mimetics had no effect on bacterial growth rates. Colony counts were performed on bacteria treated with mimetics. These studies demonstrated that incubation with the MV-II-065 altered the light absorbance of the bacteria. Bacteria concentrations standardized by absorbance at 550 nm gave falsely low values in bacteria treated with the mimetics, resulting in higher numbers of bacteria in mimetic treated populations compared to controls. In future studies examining the functional effect of MV-II-065, the bacterial concentrations will have to be verified using colony counts prior to performing phagocytosis assays.