In an antibiotic susceptibility test (aka antibiogram), the sensitivity of a bacterial strain regarding certain antibiotic concentrations is analyzed.
See here for the according wikipedia-entry. The sensitivity is measured by the diameter (in mm) of the resulting inhibition zone (see picture).
Example for an antibiotic susceptibility test
Strains showing larger inhibition zones are regarded as sensitive and strains that show no inhibition zone are regarded as resistant to the tested antibiotic concentration.
Breakpoints are the diameter where a strain is classified as resistant. These breakpoints are strain-specific and are not only dependent on the antibiotic concentration, but also on the cultivation conditions. Breakpoints can be looked up at the EUCAST-website.
In BacDive the inhibition zone diameters are displayed in tables. The according cultivation conditions can be found in the header (grey). The concentration of the antibiotics are displayed within the mouse-over function.
Example table with antibiotic susceptibility data for Acinetobacter calcoaceticus.
Important to notice is that in BacDive only raw data are displayed. No statistics were applied to this data and therefore the single diameters may deviate between different susceptibility tests, as can be seen in the example for "Penicillin G".