Showing the growth rate heterogeneity (PGRH) at different antibiotic concentrations.

PGRH shows the variation in growth rate between colonies in the same growth environment, which we define as the standard deviation of colony growth rate for one pad at one point in time. This value is averaged between 1 to 2.5 hours of incubation on the MAP. The markers show mean and standard deviation between repeats. There are at least three repeats per antibiotic/species combination. The white marker in each plot shows the concentrations selected for subsequent PGRH analysis. The vertical lines correspond to the IC₁₀ and IC₉₀ concentrations where the growth rate is inhibited by 10% and 90%, respectively. We see that for some antibiotics, high concentrations produce a much higher PGRH and that this change is linked to the MIC. For others, like chloramphenicol, there is a drop in PGRH linked to the use of the antibiotic, also around the MIC. The plots for <i>E.coli</i> with tetracycline, rifampicin, and ampicillin are also presented in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1012924#ppat.1012924.g002" target="_blank">Fig 2</a> and are included here for completeness. (PDF)