Wang Xinna, Leung Albert Wingnang, Hua Heyu, Xu Chuanshan, Ip Margaret
School of Chinese Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
Department of Microbiology, Faculty of Medicine, The Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
J Acoust Soc Am. 2015 Oct;138(4):2548-53. doi: 10.1121/1.4932014.
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.
表皮葡萄球菌是一种引起生物膜相关感染的机会致病菌。为了研究竹红菌素B对浮游培养状态下产生物膜的表皮葡萄球菌的声动力作用，将一株产生物膜的表皮葡萄球菌（ATCC 35984）与竹红菌素B孵育，然后以1.56 W/cm(2)的强度、1 MHz的频率在连续模式下暴露于超声5分钟。经竹红菌素B声动力处理后，采用菌落计数法测量细菌生长情况。使用碘化丙啶染色的流式细胞术研究细菌膜完整性。使用二氯荧光素二乙酸酯（DCFH-DA）染色的流式细胞术测量细胞内活性氧（ROS）水平。结果表明，竹红菌素B的声动力作用以竹红菌素B剂量依赖性方式显著诱导表皮葡萄球菌存活率降低，在竹红菌素B（40 μM）与强度为1.56 W/cm(2)的超声处理联合作用5分钟后，观察到细菌数量减少了4个对数级。声动力处理后，细菌膜完整性明显受损，细胞内ROS水平显著升高。研究结果表明，竹红菌素B的声动力作用可能通过增加细胞内ROS水平导致细菌膜完整性受损，从而对浮游状态下产生物膜的表皮葡萄球菌具有显著的抗菌活性。
