Patent ID: 8889349

Claim:
A method for testing cells or microorganisms, comprising multiply staining the cells or microorganisms with two membrane-permeable fluorochromes whose fluorescence amounts are amplified by binding to a nucleic acid and one membrane-impermeable fluorochrome whose fluorescence amount is amplified by binding to a nucleic acid, simultaneously irradiating a plurality of excitation lights having different specific peak wavelengths on a sample fluid containing the multiply stained cells or microorganisms, measuring fluorescences emitted from the irradiated sample fluid using fluorescence cytometry, detecting the cells or microorganisms in the irradiated sample fluid based on the fluorescences emitted from the cells or microorganisms, and discriminating between the multiply stained cells or microorganisms and particles formed by self-aggregation of the membrane-permeable fluorochromes or the membrane-impermeable fluorochromes wherein objects emitting a plurality of fluorescences derived from the two membrane-permeable fluorochromes are determined to be the multiply stained cells or microorganisms, and objects emitting single fluorescence are determined to be the particles formed by aggregation of the flurochromes, and wherein a membrane-permeable fluorochrome which has a fluorescence spectrum peak at less than 550 nm and a membrane-permeable fluorochrome which has a fluorescence spectrum peak at 680 nm or more are used as the two membrane-permeable fluorochromes, and a membrane-impermeable fluorochrome which has a fluorescence spectrum peak at 550 nm or more and less than 680 nm is used as the one membrane-impermeable fluorochrome to multiply stain the cells or microorganisms.