Figure 1.

The measured minimum inhibitory concentration (MIC) levels off in the limit of small densities, asymptotically approaching the single-cell MIC (scMIC)

1. Design of the inoculum effect experiment. The initial cell density determines whether in 20 h, the population survives at a given antibiotic concentration. On the left, the cell density is not enough to produce the necessary amount of enzyme to break down the antibiotic. Therefore, in 20 h all cells are dead. On the right, the cell density is high enough to produce enough enzymes, and therefore, in 20 h the population survives the treatment and no antibiotic is left in the media.
2. We define the scMIC as the measured MIC at low starting cell densities. The measured MIC of TEM-20 (reference) strain varies by three orders of magnitude depending upon the starting cell density and asymptotically approaches a limit at low cell densities. The gray bars correspond to the initial cell densities for MIC* and scMIC. The error bars are the maximum of a discretization error and the standard error of the mean of three measurements.

Source data are available online for this figure.