A rapid method for the quantitation of various live 
cell types is described. The method may include a variety of steps including: 1) suspending the cells in a detergent-like compound, 2) isolating the washed cells by 
centrifugation or 
filtration, 3) resuspending the cells in a solution that contains a 
preservative, a fluorescent dye and a compound such as dequalinium which can be taken up by the cells, 4) measuring the 
fluorescence increase over time of the 
cell-dye mixture with a simple 
fluorometer, and 5) measuring the native 
fluorescence of the cells. This new 
cell fluorescence method correlates with other methods of enumerating cells such as the 
standard plate count, the 
methylene blue method and the slide viability technique. The method is particularly useful in several applications such as: a) quantitating 
bacteria in milk, yogurt, cheese, meat and other foods, b) quantitating 
yeast cells in 
brewing, 
fermentation and 
bread making, c) quantitating mammalian cells in research, food and 
clinical settings. The method is especially useful when both total and 
viable cell counts are required such as in the 
brewing industry. The method can also be employed to determine the 
metabolic activity of cells in a sample. The apparatus, device, and / or 
system used for cell quantitation is also disclosed.