(a) Bacterial cultures of Escherichia coli (E. coli, ATCC 25922) and Staphylococcus aureus (S. aureus ATCC 25923) without and with treatment with P4, DCM7-β-CD, and Spd-4. (b) Relative bacterial viability of Escherichia coli (E. coli, ATCC 25922) and Staphylococcus aureus (S. aureus ATCC 25923) without and with treatment with P4, DCM7-β-CD, and Spd-4. The concentrations of P4, DCM7-β-CD, and Spd-4 (P4/DCM7-β-CD) were 20, 20, and 20 μM/20 μM, respectively. **P < 0.01. Bacteria were ×103, × 104 and ×105 diluted; the viability in Figure 7b is the ratio of the counted bacterium number (× 105 diluted) in each group relative to that of the control group (bacteria alone).