Efforts to treat bloodstream infections, which have a relatively high mortality rate, are delayed by the lengthy multi-step process required to identify the causative bacteria. Due to this delay, broad spectrum antibiotics are prescribed on a presumptive basis, leading to the rise of antibiotic resistant microorganisms. Here, as proof of principle, we describe a colourimetric sensor that rapidly identifies opportunistic pathogenic bacteria in a single step in TSB media. The device is composed of a reaction chamber and an array of chemoresponsive dyes deposited on a substrate in a prearranged pattern. This single step, disposable, automated system can detect and identify of eight strains of bacteria, starting with clinically relevant concentrations bacteria in twenty four hours in TSB media. Thus, this technology may be used to streamline the current blood culture process by combining detection and identification in a single step.