High frequency equipment promotes antibacterial effects dependent on intensity and exposure time.

Background: The indiscriminate use of antibiotics has caused bacteria to develop mechanisms of resistance to antibacterial agents, limiting treatment options. Therefore, there is a great need for alternative methods to control infections, especially those related to skin. One of the alternative methods is the high frequency equipment (HFE), which is used on skin conditions as an analgesic, an anti-inflammatory, and mainly to accelerate cicatricial processes and have a bactericidal effect through the formation of ozone. This research investigated the antibacterial effect of HFE on standard cultures of bacteria.

Materials and methods: Dilutions (104 colony forming unit mL-1 ) were performed for Enterobacter aerogenes and Staphylococcus aureus with 24-hour growth bacteria. Then, 1 μL of each dilution was pipetted into suitable medium and the HFE flashing technique was used at intensities of 6, 8 and 10 mA for 30, 60, 90, 120 and 180 seconds. The control group received no treatment. Plates were incubated at 37°C for 24 hours and then read.

Results: The spark at intensity of 6 mA had no bactericidal effect on the E. aerogenes ; however, a significant bacterial growth reduction occurred at intensity of 8 mA after 120 and 180 seconds, and at 10 mA, reduction in bacterial growth could already be verified at 30 seconds and total bacterial growth inhibition occurred in 180 seconds. For S. aureus , there was a strong bacterial growth inhibition at all intensities used; however, at 6 mA, absence of bacterium growth after 120 and 180 seconds was observed. By increasing the flashing intensity to 8 and 10 mA, it was observed that the bacterium growth was inhibited after only 30 seconds of irradiation.

Conclusion: The HFE has time-dependent antibacterial effects against E. aerogenes and S. aureus bacteria that have several resistance mechanisms.