Combined an acoustic pressure simulation of ultrasonic radiation and experimental studies to evaluate control efficacy of high-intensity ultrasound against Staphylococcus aureus biofilm.

• Acoustic pressure was simulated as a standardized parameter to reflect sono-effect. • High-intensity ultrasound efficacy against Staphylococcus aureus biofilm was studied. • Bactericidal rate of high-intensity ultrasound (HIU, 20 kHz, 240 W) was limited. • Detachment of S. aureus biofilm was efficient by using the HIU. • HIU (60 W, 15 h) stimulated S. aureus biofilm formation and enhanced its resistance. This study evaluated efficacy of high-intensity ultrasound (HIU) on controlling or stimulating Staphylococcus aureus biofilm. Acoustic pressure distribution on the surface of glass slide cultivated S. aureus biofilm was first simulated as a standardized parameter to reflect sono-effect. When the power of HIU was 240 W with acoustic pressure of −1.38×105 Pa, a reasonably high clearance rate of S. aureus biofilm was achieved (96.02%). As an all-or-nothing technique, the HIU did not cause sublethal or injury of S. aureus but inactivate the cell directly. A further evaluation of HIU-induced stimulation of biofilm was conducted at a low power level (i.e. 60 W with acoustic pressure of −6.91×104 Pa). The low-power-long-duration HIU treatment promoted the formation of S. aureus biofilm and enhanced its resistance as proved by transcriptional changes of genes in S. aureus , including up-regulations of rbf , sigB , lrgA , icaA , icaD , and down-regulation of icaR. These results indicate that the choose of input power is determined during the HIU-based cleaning and processing. Otherwise, the growth of S. aureus and biofilm formation are stimulated when treats by an insufficiently high power of HIU. [ABSTRACT FROM AUTHOR]