An improved method and related apparatus for detecting bacteria viability and drug effects using metabolic monitoring. A fluorescent material which is quenched by oxygen is co-localized with the target bacteria, and fluorescence signal is detected at the co-localized places. In some embodiments, the fluorescent material is a fluorescent nanoparticle mixed with the target bacteria in the sample, and co-localization is enhanced using centrifugation, electrophoresis, microflow path modified with antibodies, magnetic force, etc. In some other embodiments, the fluorescent material is a fluorescent film or 3-D matrix immobilized in the bacterial culture chamber, and bacteria in the sample is gathered into localized regions of the bacteria culture chamber where the fluorescent film or 3-D matrix is present by ways of centrifugation, electrophoresis or microflow path. Plasmonic nanoparticles with a metal core and plasmonic film with a metal film may be used as the fluorescent nanoparticles and fluorescent film.