The present invention relates to a method for rapidly monitoring a stress response of a cell to a stressor and determining the magnitude of the stress response; a method for rapidly detecting the presence or absence of a cell by monitoring a stress response of the cell if said cell is present, or the absence of the stress response if said cell is absent or dead; and a method for determining a predictive outcome for the susceptibility of a cell to a selected concentration of a bio-active agent or environmental factor and a level of stress of the cell at the selected concentration of the bio-active agent. Also disclosed are kits for carrying out the methodology according to an embodiment of the invention.