Free radical formation induced by ultrasound and its biological implications

The effect of gentamicin upon planktonic cultures of Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, and Staphylococcus aureus was measured with and without application of 67-kHz ultrasonic stimulation. The ultrasound was applied at levels that had no inhibitory or bactericidal activity against the bacteria. Measurements of the MIC and bactericidal activity of gentamicin against planktonic cultures of P. aeruginosa and E. coli demonstrated that simultaneous application of 67-kHz ultrasound enhanced the effectiveness of the antibiotic. A synergistic effect was observed and bacterial viability was reduced several orders of magnitude when gentamicin concentrations and ultrasonic levels which by themselves did not reduce viability were combined. As the age of the culture increased, the bacteria became more resistant to the effect of the antibiotic alone. Application of ultrasound appeared to reverse this resistance. The ultrasonic treatment-enhanced activity was evident with cultures of P. aeruginosa and E. coli but was not observed with cultures of gram-positive S. epidermidis and S. aureus. These results may have application in the treatment of bacterial biofilm infections on implant devices, which infections are usually more resistant to antibiotic therapy.

Ultrasonic enhancement of antibiotic action on gram-negative bacteria.

The effect of the antibiotics gentamicin, streptomycin, kanamycin, tetracycline, and ampicillin on planktonic cultures of Enterobacter aerogenes, Serratia marcescens, Salmonella derby, Streptococcus mitis, and Staphylococcus epidermidis with and without an application of 70 kHz ultrasound was studied. The ultrasound was applied at levels that had no inhibitory effect on planktonic cultures of bacteria. Measurements of viability at, above, and below the minimum inhibitory concentration of the above antibiotics on the planktonic cultures of these bacteria showed that a simultaneous application of 70 kHz ultrasound and antibiotic significantly increased the effectiveness of selected antibiotics. Bacterial viability was reduced several orders of magnitude when harmless levels of ultrasound were combined with some antibiotics, especially the aminoglycosides. Similar synergistic effects of combined ultrasound and antibiotic treatment were seen in both Gram-positive and Gram-negative bacteria with several classes of antibiotics. These results may have application in the treatment of bacterial infections normally resistant to some antibiotics.

/pdf/ultrasonic-enhancement-of-antibiotic-action-on-several-3kx7qvuvtc.pdf

Ultrasonic enhancement of antibiotic action on several species of bacteria.

Radiosensitization with chemotherapeutic agents.

Background: Bacterial biofilms have been implicated in the pathogenesis of chronic rhinosinusitis. In the laboratory setting, ultrasound is effective in disrupting such biofilms; however, few clinical studies have evaluated the role of therapeutic ultrasound in chronic rhinosinusitis. Objective: This study was performed to investigate the short-term effectiveness of therapeutic ultrasound as a treatment modality for chronic rhinosinusitis. Methods: Twenty-two patients with a positive history of chronic rhinosinusitis, according to the criteria set out by the Rhinosinusitis Task Force, together with a previous computed tomography scan compatible with a diagnosis of chronic rhinosinusitis, and who had failed previous, aggressive medical management, were treated with therapeutic pulsed ultrasound at 1 MHz two to three days per week for six sessions. Patients completed an assessment of individual sinus symptom severity and the 20-Item Sino-Nasal Outcome Test questionnaire before treatment, prior to session four and after completion of session six. Results: Two patients were unable to complete the study protocol. After completion of session six, 18 patients had experienced improvement in symptoms, while two patients noted a worsening of symptoms. Median percentage improvement of the total overall symptom score was 16.7 per cent (Wilcoxon signed rank, p < 0.001). The 20-Item Sino-Nasal Outcome Test score improved by 34.1 per cent (Wilcoxon signed rank, p < 0.0001). Conclusion: This study demonstrated a significant improvement in chronic rhinosinusitis symptoms after a six-session course of pulsed ultrasound therapy. Treatment with ultrasound alone or combined with antibiotics may provide a strategy to target biofilms on the sinus mucosa. Therapeutic ultrasound warrants further investigation as a potential treatment modality for chronic rhinosinusitis.

Therapeutic ultrasound as treatment for chronic rhinosinusitis: preliminary observations

https://www.tandfonline.com/doi/pdf/10.1080/09553008014550131

M Lewis

Papers

The Effect of Ultrasound at 1·5 MHz on Escherichia Coli