The effects of high intensity focused ultrasound on biofilms formed by Pseudomonas aeruginosa
Reference: Journal of the Acoustical Society of America (2018) 143: 1928-1928

Bacterial infections are increasingly difficult to treat due to their growing resistance to antibiotics. Most of these bacterial infections form a biofilm that limits the effectiveness of the antibiotic. Biofilms are microbial cells that are protected by a self-generated matrix of extracellular polymeric substances. In addition to their intrinsic antibiotic resistance, these biofilms are able to respond to the stresses from the antibiotic by inducing drug resistance mechanisms. Currently, the strategy to combat drug resistance is to develop novel drugs, however, the rate of drug development is being surpassed by the rate of drug resistance. There is therefore a need for alternative means in enhancing the efficacy of current drug therapeutics. We propose to use of high intensity focused ultrasound (HIFU) to disrupt the biofilm and promote drug penetration. However, the effects of HIFU on these bacterial communities remain unknown. Here we report on microstructural changes within biofilms formed by Pseudomonas aeruginosa due to exposure to HIFU at 500 kHz center frequency. Changes to the biofilm were nondestructively measured through impedance spectroscopy and confocal microscopy. Biofilms were shown to induce cavitation (as measured by a passive cavitation detector) at relatively low pressure amplitudes suggesting the presence of cavitation nuclei within the extracellular matrix.

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Bharatula L. D., Marsili E., Rice S. A., Kwan J. J.