Dispersing and Sonoporating Biofilm-Associated Bacteria with Sonobactericide
Kirby R. Lattwein,
Inés Beekers,
Joop J. P. Kouijzer,
Mariël Leon-Grooters,
Simone A. G. Langeveld,
Tom van Rooij,
Antonius F. W. van der Steen,
Nico de Jong,
Willem J. B. van Wamel,
Klazina Kooiman
Affiliations
Kirby R. Lattwein
Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
Inés Beekers
Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
Joop J. P. Kouijzer
Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
Mariël Leon-Grooters
Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
Simone A. G. Langeveld
Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
Tom van Rooij
Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
Antonius F. W. van der Steen
Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
Nico de Jong
Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
Willem J. B. van Wamel
Department of Medical Microbiology and Infectious Diseases, Erasmus MC University Medical Center Rotterdam, Office Na9182, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
Klazina Kooiman
Department of Biomedical Engineering, Thoraxcenter, Erasmus MC University Medical Center Rotterdam, Office Ee2302, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
Bacteria encased in a biofilm poses significant challenges to successful treatment, since both the immune system and antibiotics are ineffective. Sonobactericide, which uses ultrasound and microbubbles, is a potential new strategy for increasing antimicrobial effectiveness or directly killing bacteria. Several studies suggest that sonobactericide can lead to bacterial dispersion or sonoporation (i.e., cell membrane permeabilization); however, real-time observations distinguishing individual bacteria during and directly after insonification are missing. Therefore, in this study, we investigated, in real-time and at high-resolution, the effects of ultrasound-induced microbubble oscillation on Staphylococcus aureus biofilms, without or with an antibiotic (oxacillin, 1 μg/mL). Biofilms were exposed to ultrasound (2 MHz, 100–400 kPa, 100–1000 cycles, every second for 30 s) during time-lapse confocal microscopy recordings of 10 min. Bacterial responses were quantified using post hoc image analysis with particle counting. Bacterial dispersion was observed as the dominant effect over sonoporation, resulting from oscillating microbubbles. Increasing pressure and cycles both led to significantly more dispersion, with the highest pressure leading to the most biofilm removal (up to 83.7%). Antibiotic presence led to more variable treatment responses, yet did not significantly impact the therapeutic efficacy of sonobactericide, suggesting synergism is not an immediate effect. These findings elucidate the direct effects induced by sonobactericide to best utilize its potential as a biofilm treatment strategy.
