Low-Frequency Ultrasound Enhances Bactericidal Activity of Antimicrobial Agents against Klebsiella pneumoniae Biofilm.

Klebsiella pneumoniae biofilms on inserted devices have been proposed as one of the important factors for hospital-acquired infections, which cause increased resistance to currently used antibiotics. Therefore, it is urgently necessary to develop new treatments with more efficient bacterial clearance. In the present study, we aimed at investigating whether low-frequency ultrasound (LFU) could enhance the bactericidal activity of antimicrobial agents (meropenem (MEM), tigecycline (TGC), fosfomycin (FOM), amikacin (AMK), and colistin (COL)) against K. pneumoniae biofilm infection. K. pneumoniae biofilm was cultivated on the catheter in vitro. Synergistic effects were observed in groups of single ultrasound (S-LFU, 5 min) or multiple ultrasound (M-LFU, 5 min every 8 h (q8h)) in combination with MEM, TGC, and FOM. However, AMK and COL did not show the synergistic effect with either S-LFU or M-LFU. S-LFU in combination with FOM only significantly decreased bacterial counts right after ultrasound, while M-LFU could prolong the synergistic effect until 24 h. The results showed that LFU in combination with antimicrobial agents had a synergistic effect on K. pneumoniae biofilm, and M-LFU might extend the time of synergistic effect compared with S-LFU.

Low-Frequency Sonophoresis of Chinese Medicine Formula Improves Efficacy of Malignant Pleural Effusion Treatment.

OBJECTIVE: To evaluate whether low-frequency ultrasound-facilitated transdermal delivery of a Chinese medicine (CM) formula could improve the efficacy of intrapleural administration of interleukin-2 (IL-2) in treatment of malignant pleural effusion (MPE). METHODS: A total of 110 eligible participants were randomized into the low-frequency sonophoresis (LFS) of CM (LSF/CM) group (55 cases) and the control group (55 cases) by simple randomization using a random number table. The control group was treated with an intrapleural administration of IL-2; and the LFS/CM group was treated with LFS of a CM gel formulation, combined with the same IL-2 injection as in the control group. The CM formula consisted of Semen Lepidii, Semen Sinapis, Ramulus Cinnamomi, Poriacocos, Herba Lycopi, and Radix Paeoniae Rubra. After 2-week treatment, the therapeutic outcome was determined by the change of the amount of MPE, which was evaluated by B-scan ultrasound and/or chest X-ray, and the change of quality of life (QOL) scores, which were evaluated by the Eastern Cooperative Oncology Group (ECOG) performance status. RESULTS: A significantly higher objective remission rate (ORR) was obtained with intrapleural IL-2 plus LFS/CM than IL-2 treatment alone (P=0.049). In addition, more patients in the LFS/CM group than in the control group had an improved QOL score (P=0.048), and no patients in the LFS/CM group had a reduced QOL. CONCLUSION: LFS of CM formulation could effectively alleviate MPE and improve the QOL of cancer patients.

Topical Delivery of Modified Da-Cheng-Qi Decoction () Using Low-Frequency Ultrasound Sonophoresis for Refractory Metastatic Malignant Bowel Obstruction: An Open-Label Single-Arm Clinical Trial.

OBJECTIVE: To evaluate the efficacy and safety of topical delivery of modified Da-Cheng- Qi Decoction (, MDCQD) by low-frequency ultrasound sonophoresis (LFUS) in patients with refractory metastatic malignant bowel obstruction (MBO) using an objective performance criteria (OPC) design. METHODS: Fifty patients with refractory metastatic MBO were enrolled in this open-label single-arm clinical trial. Alongside fasting, gastrointestinal decompression, glycerol enema, intravenous nutrition and antisecretory therapy, a 50 g dose of MDCQD (prepared as a hydrogel) was applied through topical delivery at the site of abodminal pain or Tianshu (S 25) using LFUS for 30 min, twice daily for 5 consecutive days. The overall outcome was the remission of intestinal obstruction, and improvement on abdominal pain, abdominal distention, nausea and vomiting scores. Indicators of safety evaluation included liver and renal function as well as blood coagulation indicators. RESULTS: Among 50 patients, 5 patients (10%) showed complete remission of intestinal obstruction and 21 patients (42%) showed improvement of intestinal obstruction. The overall remission rate of bowel obstruction was 52%. The results of the symptom score, based on the severity and frequency of the episode, are as follows: 26 patients (52%) showed improvment on symptom scores, 20 patients (40%) did not respond to treatment, and 4 patients (8%) discontinued treatment due to intolerance. No serious adverse effects or abnormal changes on liver and renal function or blood coagulation were observed. CONCLUSION: Topical delivery of MDCQD at 100 g/day using LFUS can improve the treatment response in patients with refractory metastatic MBO.

Multiple Low Frequency Ultrasound Enhances Bactericidal Activity of Vancomycin against Methicillin-Resistant Staphylococcus aureus Biofilms.

Methicillin-resistant Staphylococcus aureus (MRSA) biofilm infections are difficult to treat due to the high antimicrobial resistance of biofilm. Therefore, new treatments are needed for more effective bacteria clearance. This study was to investigate whether low frequency ultrasound (LFU) can enhance the activity of antimicrobial agents against MRSA biofilm infection. Broth microdilution method was used to determine the minimum inhibitory concentration (MIC) of vancomycin (VAN), linezolid (LIN), and levofloxacin (LEV) against three clinical isolated strains, including one methicillin-susceptible Staphylococcus aureus (MSSA) strain and two MRSA strains. Effects of various influencing factors, such as antimicrobial agents, drug concentrations, ultrasonic intensity, and single (S-LFU, 5 or 15 min) or multiple ultrasound (M-LFU, 5 min every 8 h), on the inhibition of biofilms were investigated. The bactericidal effects of S-LFU or M-LFU on MRSA or MSSA biofilms were determined by colony counts. Right after ultrasound, synergistic effects were observed in groups of S-LFU combined with three antimicrobial agents against MSSA biofilm, but for MRSA biofilm, only S-LFU plus VAN had synergistic effect. At the time point of 24 h, M-LFU plus VAN treatment had synergistic bactericidal effect against MRSA and MSSA biofilms, and the synergy showed that VAN is concentration-dependent, but no synergistic effects were observed in all S-LFU combination groups. In conclusion, combination of M-LFU and antimicrobial agents had a better synergistic effect than S-LFU against MRSA or MSSA biofilm. LFU may be useful in treating biofilm infection in the future.

Low-Frequency Ultrasound Enhances Paclitaxel Efficacy in EMT6 Subcutaneous Tumors in Balb/c Mice.

BACKGROUND: The objective of this study was to explore the effects of 30 kHz ultrasound on the efficacy of paclitaxel in subcutaneous breast tumors in Balb/c mice in vivo. MATERIALS AND METHODS: 40 Balb/c female mice were divided into 5 groups: model control group, paclitaxel intraperitoneal (ip) group (20 mg/kg, ip, at 3 day intervals for a total of 3 doses (q3d×3)), paclitaxel intratumoral (it) group (20 mg/kg, it, q3d×3), paclitaxel intraperitoneal (20 mg/kg, ip, q3d×3) combined with low-frequency ultrasound (LFU) group, and paclitaxel intratumoral (20 mg/kg, it, q3d×3) combined with LFU group. Ultrasound parameters were 30 kHz, 200 MW intensity, 15 min, q3d×3. The antitumoral effect was determined by examining the tumor weight in subcutaneously inoculated EMT6 breast carcinoma models in Balb/c mice. All subcutaneous tumors were examined using high performance liquid chromatography (HPLC) upon completion of the experiments. Drug concentrations in the subcutaneous tumors were also analyzed using HPLC. Finally, paraffin sections of the subcutaneous tumors were made, and after hematoxylin and eosin staining, the tumor morphology was examined under a light microscope. RESULTS: LFU combined with paclitaxel significantly restrained tumor growth in transplanted subcutaneous EMT6 tumors in Balb/c mice, and this effect correlated with increased local concentrations of paclitaxel in the tumors. Body weight measurement did not reveal significant adverse effects on the Balb/c mice during the study. CONCLUSION: LFU combined with paclitaxel has a significant synergistic effect in the treatment of breast cancer.

Low-Frequency Ultrasound Enhances Antimicrobial Activity of Colistin-Vancomycin Combination against Pan-Resistant Biofilm of Acinetobacter baumannii.

Acinetobacter baumannii biofilms in catheters are very difficult to treat. Low-frequency ultrasound (LFU) may improve bactericidal or bacteriostatic activity. However, no previous studies have been reported on its efficacy against pan-resistant biofilms of A. baumannii. This study was designed to investigate whether LFU can enhance the activity of colistin, vancomycin and colistin-vancomycin combinations against pan-resistant biofilms of A. baumannii. The efficacy of colistin combinations was determined using the fractional inhibitory concentration index (FICI). The antibacterial effect was determined from bacteria counts in biofilms and the establishment of 24-h time-kill curves. A significantly synergistic effect was detected between colistin and vancomycin (FICI <0.05). We found that although application of LFU (40 kHz, 600 mW/cm(2), 30 min, duty cycle 1:9) alone or in combination with a single agent failed to significantly reduce bacteria counts in biofilms, it apparently enhanced the antibacterial effectiveness of combinations of these agents. Moreover, higher concentrations of colistin in the combination treatments resulted in a better ultrasound-enhanced antibacterial effect. In 24-h time-kill curves, the combination of colistin (8 µg/mL) plus vancomycin (4 µg/mL) with LFU caused a significant reduction in bacteria counts in biofilms after 8 h and a continuing decline until 24 h. Bacterial counts were reduced by 3.77 log(CFU/mL) by LFU plus combinations, compared with combinations without LFU at 24 h. Our results indicate that LFU in combination with colistin plus vancomycin may be useful in treating pan-resistant A. baumannii infections.