Bacterial Inhibition by Electrical Stimulation

Abstract

Significance: Much evidence shows that electrical stimulation (ES) promotes the wound healing process. The inhibitory effect of ES on bacterial growth has been proposed as a mechanism to explain the useful effects of ES on wound healing. Bacterial burden has been associated with chronic wounds. The extensive use of antibiotics can lead to the spread of multiple drug resistant bacteria. Whether biophysical energies, such as ES, can be used as a treatment modality against pathogenic microorganisms remains an open question. Recent Advances: The research literature provides evidence for useful effects of ES in terms of inhibition of bacterial growth. The type of ES, its polarity, and the intensity of the current play a major role in establishment of antibacterial effects. Both direct current (DC) and high voltage pulse current are more effective at inhibiting bacterial growth than are other types of ES. The exact mechanism underlying the antibacterial effects of ES is not clear. Critical Issues: Available evidence indicates that microampere DC (μADC) is better than other ES types for inhibition of bacterial growth. The results of most studies also support the application of cathodal current for bacterial growth inhibition. The current intensity of ES would appear to be tolerable by humans if used clinically for treatment of infected wounds. Future Directions: The cathodal μADC appears to be more effective for inhibition of microorganism growth. Further research, especially in vivo, is necessary to clarify the inhibitory effects of ES on wound bacterial infections.

Giti Torkaman, PhD

Figure 1.

Various waveforms of electrical stimulation (ES) are available in research, including (A) high-voltage pulsed current, (B) direct current, and (C) alternating current.

Figure 2.

A diagram of direct and indirect effects of ES on microorganism growth. It is suggested that plasma transmembrane potential is related to the cell cycle processes. Low transmembrane potential facilitates cell proliferation, while high potential tends to inhibit it. Transmembrane potential of microbes differs from other cells, such as fibroblasts. Thus, different characteristics of the membrane of microbes might be responsible for inhibition of microbe proliferation by ES.

Figure 3.

This scheme shows that pH at the cathode (negative pole) tends toward alkaline and H₂O₂, as an antibacterial substance, produced at the cathode.

Figure 4.

This scheme shows that pH at the anode (positive pole) tends toward acidic and chlorine molecules, as an antibacterial substance, produced at the anode.