title: Sonodynamic action of hypocrellin B on biofilm-producing Staphylococcus epidermidis in planktonic condition.
abstract: 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/cm(2) 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 μM) and ultrasound sonication with the intensity of 1.56 W/cm(2) for 5 min. Bacterial membrane integrity was notably damaged and the level of intracellular ROS level was remarkably increased after sonodynamic treatment. The findings demonstrated that sonodynamic action of hypocrellin B had significant antibacterial activity on biofilm-producing Staphylococcus epidermidis in planktonic condition probably through increasing intracellular ROS level to cause damage to bacterial membrane integrity.
authors.affiliation: School of Chinese Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Xinna
authors.initials: X
authors.lastname: Wang
authors.affiliation: School of Chinese Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Albert Wingnang
authors.initials: AW
authors.lastname: Leung
authors.affiliation: School of Chinese Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Heyu
authors.initials: H
authors.lastname: Hua
authors.affiliation: School of Chinese Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Chuanshan
authors.initials: C
authors.lastname: Xu
authors.affiliation: Department of Microbiology, Faculty of Medicine, The Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Margaret
authors.initials: M
authors.lastname: Ip
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D058491:Bacterial Load; D018441:Biofilms / Q000187:drug effects*; D002462:Cell Membrane / Q000187:drug effects; D004203:Disinfection / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D010569:Perylene / Q000031:analogs & derivatives* / Q000494:pharmacology; D011809:Quinones / Q000494:pharmacology*; D011897:Random Allocation; D017382:Reactive Oxygen Species; D013010:Sonication / Q000379:methods*; D013212:Staphylococcus epidermidis / Q000187:drug effects* / Q000254:growth & development; D013535:Suspensions; D014640:Vancomycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D011809:Quinones; D017382:Reactive Oxygen Species; D013535:Suspensions; D010569:Perylene; D014640:Vancomycin; C064522:hypocrellin B