Zhu Han-Xiao, Cai Xun-Zi, Shi Zhong-Li, Hu Bin, Yan Shi-Gui
Department of Orthopaedic Surgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, No. 88 Jiefang Road, Hangzhou 310009, China.
Biomed Res Int. 2014;2014:142168. doi: 10.1155/2014/142168. Epub 2014 May 15.
Previous research has found that low-intensity ultrasound enhanced the lethal effect of gentamicin on planktonic E. coli. We aimed to further investigate whether microbubble-mediated low-intensity ultrasound could further enhance the antimicrobial efficacy of gentamicin. The planktonic E. coli (ATCC 25922) was distributed to four different interventions: control (GCON), microbubble only (GMB), ultrasound only (GUS), and microbubble-mediated ultrasound (GMUS). Ultrasound was applied with 100 mW/cm(2) (average intensity) and 46.5 KHz, which presented no bactericidal activity. After 12 h, plate counting was used to estimate the number of bacteria, and bacterial micromorphology was observed with transmission electron microscope. The results showed that the viable counts of E. coli in GMUS were decreased by 1.01 to 1.42 log10 CFU/mL compared with GUS (P < 0.01). The minimal inhibitory concentration (MIC) of gentamicin against E. coli was 1 μ g/mL in the GMUS and GUS groups, lower than that in the GCON and GMB groups (2 μ g/mL). Transmission electron microscopy (TEM) images exhibited more destruction and higher thickness of bacterial cell membranes in the GMUS than those in other groups. The reason might be the increased permeability of cell membranes for gentamicin caused by acoustic cavitation.
先前的研究发现，低强度超声可增强庆大霉素对浮游大肠杆菌的致死作用。我们旨在进一步研究微泡介导的低强度超声是否能进一步增强庆大霉素的抗菌效果。将浮游大肠杆菌（ATCC 25922）分为四种不同的干预组：对照组（GCON）、仅微泡组（GMB）、仅超声组（GUS）和微泡介导超声组（GMUS）。超声以100 mW/cm²（平均强度）和46.5 KHz施加，该强度无杀菌活性。12小时后，采用平板计数法估算细菌数量，并用透射电子显微镜观察细菌微观形态。结果显示，与GUS组相比，GMUS组中大肠杆菌的活菌数降低了1.01至1.42 log10 CFU/mL（P < 0.01）。在GMUS组和GUS组中，庆大霉素对大肠杆菌的最低抑菌浓度（MIC）为1μg/mL，低于GCON组和GMB组（2μg/mL）。透射电子显微镜（TEM）图像显示，GMUS组中细菌细胞膜的破坏更多且厚度更高。原因可能是声空化导致细胞膜对庆大霉素的通透性增加。
