Extremely minute amounts of live pathogens are rapidly detected using a piezoelectric cantilever sensor. A single pathogen is detectable in about 30 minutes. Pathogen-specific antibodies are immobilized on the sensor surface. The sensor is exposed to a medium that potentially contains the target pathogen. When target pathogens are contained in the medium, both dead and live pathogen cells bind to the immobilized antibody on the sensor surface. The attached target pathogen cells are exposed to a pathogen discriminator capable of discriminating between live cells and dead cells by increasing the mass of live cells. Example pathogens include Escherichia coli, Listeri monocytogene, and Salmonella enteritidis. Example antibodies include those that bind to the pathogenic bacteria designated as ATCC 43251, ATCC 700375, and ATCC 31194. Example pathogen discriminators include intracellular pH indicating molecules.