A rapid microtiter plate assay for measuring the effect of compounds on Staphylococcus aureus membrane potential

We developed a homogenous microtiter based assay using the cationic dye 3, 3′-Diethyloxacarbocyanine iodide, DiOC2(3), to measure the effect of compounds on membrane potential in Staphylococcus aureus. In a screen of 372 compounds from a synthetic compound collection with anti-Escherichia coli activity due to unknown modes of action at least 17% demonstrated potent membrane activity, enabling rapid discrimination of nuisance compounds.