Eradication of Bacteria by Sonodynamic Treatment

Simor Koretz, Chemical Engineering, Ariel University, Ariel, Israel
Arad David, Chemical Engineering, Ariel University, Ariel, Israel
Faina Nakonechny, Chemical Engineering, Ariel University, Ariel, Israel
Marina Nisnevitch, Chemical Engineering, Ariel University, Ariel, Israel

The increasing antibiotic resistance among bacterial species has become a serious global health problem. Therefore, it is necessary to develop alternative methods of antimicrobial treatment, which can prevent the progression of bacterial resistance to drugs. Photodynamic therapy (PDT) is one of the potential approaches to combat microbial infections, which is based on the action of photosensitizers (PS), which are activated upon absorption of visible light due to presence of conjugated double bonds in their structure. Photosensitizers can transmit the absorbed energy to dissolved oxygen to produce cytotoxic reactive oxygen species that ultimately cause irreversible damage to bacterial cellular components. Recently it was found that ultrasound can activate PS, instead of light. The main advantages of sonodynamic treatment are a facility of precise ultrasonic focusing on the treated site and a possibility to overcome the limitation of visible light penetration through skin and tissues. In this work, we demonstrate the toxicity of Rose Bengal (RB) for Staphylococcus aureus at various concentrations during short sonication at 40 kHz. It was found that cells were totally eradicated by 0.25 µM RB within one minute. Control cells treated by ultrasound only remained intact. When illuminated S. aureus cells were killed by 0.125 µM RB within three minutes. It is proposed that the sonodynamic treatment can replace PDT and can be applied for eradication of Gram-positive bacteria.bstract here