State Key Laboratory of Ultrasound Engineering in Medicine Co-Founded by Chongqing and the Ministry of Science and Technology, Chongqing Collaborative Innovation Center for Minimally Invasive and Noninvasive Medicine, College of Biomedical Engineering, Chongqing Medical University, Chongqing 400016, China.
Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai 200040, China.
FEMS Microbiol Lett. 2019 Feb 1;366(3). doi: 10.1093/femsle/fnz026.
Low-intensity and low-frequency ultrasound (LILFU) can enhance the bactericidal action of antibiotics against various sensitive bacterial species. The current study investigated the effects of LILFU combined with tobramycin on extended-spectrum beta-lactamases (ESBLs) Escherichia coli biofilms (a multi-drug resistant bacteria). The biofilms of ESBLs E. coli were established and treated with ultrasound (42 kHz and ISATA of 0.66 W/cm2) continuously for 0.5 h with and without tobramycin. The bacterial viability, the morphology and the antibiotic penetration of ESBLs E. Coli biofilms were investigated. The results demonstrated that the bacterial viability of biofilms significantly declined and the diameter of the inhibition zone was significantly increased after treatment with ultrasound combined with tobramycin compared with the controls (P < 0.05). Confocal laser scanning microscopy showed that the bacterial viability was affected most in the outer layer of ESBLs E. coli biofilms after joint treatment. The morphological structure of the biofilms was altered remarkably after joint treatment based on scanning electron microscopy, especially in regard to reduced thickness and loosened structure. These results suggest that the combination of ultrasound and tobramycin can exert synergistic bactericidal effects against biofilms formed by ESBLs E. coli.
低强度低频超声（LILFU）可以增强抗生素对各种敏感细菌的杀菌作用。本研究探讨了低强度低频超声联合妥布霉素对产超广谱β-内酰胺酶（ESBLs）大肠埃希菌生物膜（一种多药耐药菌）的影响。建立了 ESBLs 大肠埃希菌生物膜，并对其进行了超声（42 kHz 和 ISATA 为 0.66 W/cm2）处理，连续处理 0.5 小时，同时加入和不加入妥布霉素。研究了 ESBLs 大肠埃希菌生物膜的细菌活力、形态和抗生素渗透情况。结果表明，与对照组相比，联合应用超声和妥布霉素处理后，生物膜的细菌活力显著下降，抑菌圈直径显著增大（P<0.05）。共聚焦激光扫描显微镜显示，联合治疗后，ESBLs 大肠埃希菌生物膜的外层细菌活力受到的影响最大。扫描电子显微镜显示，联合治疗后生物膜的形态结构发生了明显改变，尤其是厚度减小，结构松散。这些结果表明，超声联合妥布霉素对产 ESBLs 大肠埃希菌生物膜具有协同杀菌作用。
