Application of partition affinity ligand assay (PALA) in quick test for quantitation of Staphylococcus aureus...

A novel immunochemical method for the quantitation of bacterial cells is described. The method, which is based on separation of bound from free reactants in aqueous two-phase systems has been studied both as direct and competitive binding assays, with a system consisting of intact cells of Staphylococcus aureus and human immunoglobulin G molecules. To achieve high resolution, one of the reactants was modified so that the two reactants, the bacterial cells and the immunoglobulin molecules, occurred in different phases of the phase system. When binding takes place, the partition of one of the reactants is changed. The degree of change is then correlated to the amount of reactant present. Using this method, cell numbers in the region 10(5)-10(7) can be quantified. An assay takes 40-90 min.