Bacterial colony spreading. The Y-axis represents the bacterial colony spreading in µm retrieved from the colonies of the highly (HV) and low virulent (LV) isolate inoculated modified Shieh broths 24 h after addition of the appropriate cortisol concentrations (µg/L). The latter are displayed on the X-axis. The blue dots represent the bacterial cell counts retrieved from the broths of the HV isolates, the red dots those from the broths of the LV isolates. Averaged values per cortisol concentration and per virulence group are indicated by the colored lines.