Sonodynamic action of hypocrellin B on biofilm-producing Staphylococcus epidermidis in planktonic condition.

Staphylococcus epidermidis is an opportunistic pathogen causing biofilm-associated infections. To investigate sonodynamic action of hypocrellin B on biofilm-producing Staphylococcus epidermidis in planktonic culture, a biofilm-producing strain Staphylococcus epidermidis (ATCC 35984) was incubated with hypocrellin B and then exposed to ultrasound at intensity (ISATA) of 1.56 W/cm2 with a frequency of 1 MHz in continuous mode for 5 min. After sonodynamic treatment of hypocrellin B, the bacterial growth was measured using the colony counting method. Bacterial membrane integrity was investigated using a flow cytometry with propidium iodide staining. Intracellular reactive oxygen species (ROS) level was measured using a flow cytometry with DCFH-DA staining. The results showed that sonodynamic action of hypocrellin B significantly induced survival reduction of Staphylococcus epidermidis in a hypocrellin B dose-dependent manner, and a 4-log reduction was observed after the combined treatment of hypcorellin B (40...