A collection of reagents or test strips, and other associated materials, containing multiple antibacterial/antibiotic agents (i.e., a drug intended for treatment and/or prevention of a bacterial infection, excluding mycobacterial infection) at specified concentration gradients, intended to be used to determine the degree of susceptibility or the minimum inhibitory concentration (MIC) of a range of antibacterials against a specific bacterial microorganism, isolated from a clinical specimen by culture.