Fig. 2: Amoxicillin susceptibility in the presence of 15 μg ml⁻¹ clavulanic acid.

a Broth microdilution determination of the minimum inhibitory concentration of amoxicillin alone in the 138 methicillin-resistant Staphylococcus epidermidis isolates, including 61 S2/S3 isolates and 77 R2 isolates. b Effect of clavulanic acid on susceptibility to amoxicillin. The empirical epidemiological cut-off for amoxicillin in the presence of 15 μg ml⁻¹ clavulanic acid (4.0 μg ml⁻¹) is shown as grey vertical lines (a, b). c Effect of amoxicillin alone or in combination with clavulanic acid against DEN09 in a mouse infection model. Mice were inoculated intramuscularly with around 8.5 × 10⁷ colony-forming units and treated subcutaneously with a single dose of the indicated drugs. Dunnett’s multiple comparisons tests were used to compare the effect of amoxicillin alone or in combination with clavulanic acid against vehicle treatment. Data are mean ± s.d. with n = 6 mice per group. d Population analysis profiles (PAPs) of DEN09 isolates recovered from mice treated with a single dose of vehicle alone (n = 3) or 250 mg kg⁻¹ amoxicillin in combination with 50 mg kg⁻¹ clavulanic acid (n = 3). A two-tailed unpaired Student’s t test was used to compare areas under the curve. Data are mean ± s.d. with n = 3 technical replicates per mouse. Bacterial colonies that were subjected to PAP testing are indicated in blue and orange (c, d). AMX amoxicillin, CLA clavulanic acid, VAN vancomycin, MIC minimum inhibitory concentration, c.f.u. colony-forming unit, AUC area under the curve. Source data are provided as a Source Data file.