The antibacterial effect of sonication and its potential medical application

Recent applications of ultrasonic probes include cataract removal and tennis elbow treatment. Early data support the use of ultrasonic probe debridement in the treatment of recalcitrant diabetic foot ulcers. No data are available concerning the potential antibacterial properties of the clinical grade, lower energy ultrasound probes. We investigated the effect of a clinically available ultrasonic debridement probe with respect to bacterial viability.

A commercially available Tenex sonication machine with a Tx1 probe was used for this study. Three bacterial strains, aerobic and anaerobic, were investigated, G-negative (Porphyromonas gingivalis) and G-positive bacteria (Staphylococcus aureus and Streptococcus gordonii). These bacteria were cultured and tested with sonication for varying lengths of time (10, 30, 60, and 120 s). The tested bacterial samples were plated, the number of colonies on each plate counted, and the anti-bacterial effect was calculated. Statistical analysis was conducted using a one-way analysis of variance.

Sonication exhibited a significant time-dependent antibacterial effect. Statistically significant anti-bacterial effect was observed in all three species tested. When comparing the kill rate between the control and 120 s of sonication; S. gordonii had a 34% kill rate, S. aureus had a 60% kill rate, and P. gingivalis had a 64% kill rate. When comparing control to all of the time intervals tested, S. aureus kill rate was statistically significant at all times, S. gordonii was statistically significant at all times above 10 s, and P. gingivalis was only statistically significant at 120 s.

This study demonstrates that a clinically available ultrasonic probe has an antibacterial effect against a wide spectrum of gram-positive, gram-negative, aerobic and anaerobic bacterial species. This may partially explain the dramatic healing of long-standing recalcitrant diabetic ulcers debrided with this device and may have a place in treating pathologies with bacterial mechanisms.