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Inhibition of bacterial growth in vitro following stimulation with high voltage, monophasic, pulsed current
1Physical Therapy Program, University of Michigan-Flint 48502-2186.
Abstract:
Low-intensity direct current has been reported to be effective in promoting healing of infected wounds, and these results have been assumed to apply to stimulation of wound tissue with monophasic high voltage pulsed current (HVPC). The purpose of this study was to determine whether HVPC has an inhibitory effect on growth in vitro of three bacterial species--Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa--commonly isolated from open wounds. Following exposure to HVPC, the measured zone of inhibition of bacterial growth was not significantly different between bacterial species. Inhibition at the anode (positive pole) occurred secondary to build-up of toxic end products, and inhibition at the cathode (negative pole) resulted from exposure to HVPC. Duration of exposure and voltage showed a highly significant linear relationship. Exposure to more than 250 V of HVPC for at least two hours resulted in some degree of inhibition of growth in all three bacterial species.
Insights
High voltage pulsed current (HVPC) can inhibit the growth of common wound bacteria like Staphylococcus aureus and E. coli. Exposure to over 250 V for two hours demonstrated significant bacterial growth inhibition.
Area of Science:
- Biomedical Engineering
- Microbiology
- Wound Healing Research
Background:
- Low-intensity direct current shows promise for infected wound healing.
- Previous research assumed similar effects for high voltage pulsed current (HVPC).
- The direct impact of HVPC on wound-associated bacteria requires investigation.
Purpose of the Study:
- To evaluate the in vitro inhibitory effect of HVPC on Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa.
- To determine the relationship between HVPC parameters (voltage, duration) and bacterial growth inhibition.
- To understand the mechanisms of inhibition at the anode and cathode.
Main Methods:
- Exposure of bacterial cultures to monophasic HVPC.
- Measurement of zones of inhibition around electrodes.
- Varying voltage and duration of HVPC exposure.
- Analysis of bacterial species response.
Main Results:
- HVPC demonstrated inhibitory effects on all three tested bacterial species.
- No significant difference in inhibition zones was observed between bacterial species.
- Inhibition at the cathode was directly due to HVPC exposure.
- Inhibition at the anode resulted from the accumulation of toxic byproducts.
- A significant linear relationship existed between HVPC duration and voltage and growth inhibition.
- Exposure to >250 V for ≥2 hours inhibited growth in all species.
Conclusions:
- HVPC exhibits antimicrobial properties against common wound pathogens.
- Bacterial growth inhibition is dependent on voltage and duration of HVPC exposure.
- HVPC represents a potential therapeutic modality for managing infected wounds.