Systems and methods for detecting and/or identifying target cells (e.g., bacteria) using engineered transduction particles are described herein. In some embodiments, a method includes mixing a quantity of transduction particles within a sample. The transduction particles are associated with a target cell. The transduction particles are non-replicative, and are engineered to include a nucleic acid molecule formulated to cause the target cell to produce a series of reporter molecules. The sample and the transduction particles are maintained to express the series of the reporter molecules when target cell is present in the sample. A signal associated with a quantity of the reporter molecules is received. In some embodiments, a magnitude of the signal is independent from a quantity of the transduction particle above a predetermined quantity.