title: Microbubble-mediated ultrasound enhances the lethal effect of gentamicin on planktonic Escherichia coli.
abstract: 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.
authors: Department of Orthopaedic Surgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, No. 88 Jiefang Road, Hangzhou 310009, China.
authors: Han-Xiao
authors: HX
authors: Zhu
authors: Department of Orthopaedic Surgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, No. 88 Jiefang Road, Hangzhou 310009, China.
authors: Xun-Zi
authors: 0000-0002-0595-9603
authors: XZ
authors: Cai
authors: Department of Orthopaedic Surgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, No. 88 Jiefang Road, Hangzhou 310009, China.
authors: Zhong-Li
authors: ZL
authors: Shi
authors: Department of Orthopaedic Surgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, No. 88 Jiefang Road, Hangzhou 310009, China.
authors: Bin
authors: B
authors: Hu
authors: Department of Orthopaedic Surgery, Second Affiliated Hospital, School of Medicine, Zhejiang University, No. 88 Jiefang Road, Hangzhou 310009, China.
authors: Shi-Gui
authors: SG
authors: Yan
mesh_terms: D000162:Acoustics; D000900:Anti-Bacterial Agents / Q000737:chemistry; D018441:Biofilms / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects; D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000187:drug effects*; D005839:Gentamicins / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D045423:Microbubbles; D046529:Microscopy, Electron, Transmission; D010539:Permeability; D014465:Ultrasonics / Q000379:methods*
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins