Inhibitory effects of ultrasound irradiation on Staphylococcus epidermidis biofilm

PURPOSE: We aimed to investigate whether low-intensity continuous and pulsed wave ultrasound (US) irradiation can inhibit the formation of Staphylococcus epidermidis biofilms, for potential application in the treatment of catheter-related bloodstream infections (CRBSI). METHODS: S. epidermidis biofilms that formed on the bottom surfaces of 6-well plates were irradiated on the bottom surface using the sound cell incubator system for different intervals of time. RESULTS: US irradiation with continuous waves for 24 h notably inhibited biofilm formation (p < 0.01), but the same US irradiation for 12 h had no remarkable effect. Further, double US irradiation with pulsed waves for 20 min inhibited biofilm formation by 33.6%, nearly two-fold more than single US irradiation, which reduced it by 17.9%. CONCLUSION: US irradiation of a lower intensity (I(SATA) = 6–29 mW/cm(2)) than used in a previous study and lower than recommended by the Food and Drug Administration shows potential for preventing CRBSI caused by bacterial biofilms.