FIG. 1.

Contrast between CKC and MBC methods. ⋄, CKC, which is a monotonously degressive line with an inflection (10, 250) and two asymptotes: N equal to 0 and N equal to N₀. The inflexions show that half of the inocula were killed at a concentration less than the BC₅₀, and its tangent slope is −rN₀/4. BC₁ indicates the concentration at which only one colony survives, and 2BC₅₀ indicates the point (BC₅₀, 0) symmetrical to (0, N₀). By the CKC method, the two-dimensional CKC and its parameters, BC₅₀, BC₁, and r, are obtained, and the dynamic law and changes in details are obtained. •, MBC results as >1 or 0 CFU/plate, not the numbers of CFU. Some of the inocula survive at concentrations of 1, 2, 4, 8, and 16 μg/ml; and all are killed at a concentration of 32 μg/ml. The jumps in the one-dimensional data do not allow specific MBC to be identified, nor do they allow a description of the details of bactericidal dynamics.