Table 4.
A summary of the in vivo studies that evaluated effects of electrical stimulation on bacteria that were cultured directly on the stimulating electrode
| References | Animal model | Bacteria | Stimulation type | Electrical configuration | Electrode materials* | Treatment parameters | Results |
|---|---|---|---|---|---|---|---|
| van der Borden et al. [103] | Goat tibia model of external fixation pin track infection | Staphylococcus epidermidis pin site inoculation | Current-controlled | Two electrodes connected to an external constant current source | Stainless steel external fixation pin (cathode), and platinum ring (anode) placed on skin | Constant current of 100 µA for 21 days | Constant current of 100 µA for 21 days to stainless steel external fixation pins (cathode) was able to prevent S. epidermidis pin site infections from developing in 89% of the sites evaluated |
| Del Pozo et al. [101] | Rabbit tibia model of osteomyelitis | Staphylococcus epidermidis biofilm formed on stainless steel | Current-controlled | Two electrodes connected to an external constant current source | Stainless steel intramedullary rod (cathode) and stainless steel wire (anode) wrapped around bone | Constant current of 200 µA for 21 days | Applying constant current of 200 µA to an intramedullary stainless steel rod (cathode) for 21 days produced a significant 1.5 order of magnitude reduction in the bacterial burden as compared to treatment with only doxycycline. Discoloration of the bones that were exposed to the prolonged electrical current was reported |
| Ehrensberger et al. [65] | Rodent shoulder model of implant associated infection | Methicillin-resistant Staphylococcus aureus biofilm formed on titanium electrode | Voltage-controlled | Three electrodes connected to an external potentiostat | Titanium rod (WE) implanted through humeral head; Platinum wire (CE) and sintered Ag/AgCl (RE) placed in adjacent soft tissue | − 1.8 V for 1 h | Applying − 1.8 V for 1 h significantly reduced the CFU of MRSA enumerated from the bone tissue by 87% and a titanium implant by 98% when assessed immediately following the stimulation as compared to OCP controls. Histology showed stimulation had no deleterious effect of the bone tissue |
| Nodzo et al. [83] | Rodent shoulder model of implant associated infection | Methicillin-resistant Staphylococcus aureus biofilm formed on titanium electrode | Voltage-controlled | Three electrodes connected to an external potentiostat | Titanium rod (WE) implanted through humeral head; Platinum wire (CE) and sintered Ag/AgCl (RE) placed in adjacent soft tissue | − 1.8 V for 1 h ± 1 wk of vancomycin dosing | Combining the application of − 1.8 V for 1 h with a 1-week time course of vancomycin produced a 99.8% reduction of the bone and implant bacterial burden as compared to the no treatment control animals. Histology showed stimulation had no deleterious effect of the bone tissue |
| Nodzo et al. [84] | Rodent shoulder model of implant associated infection | Methicillin-resistant Staphylococcus aureus biofilm formed on titanium electrode | Voltage-controlled | Three electrodes connected to an external potentiostat | Titanium rod (WE) implanted through humeral head; Platinum wire (CE) and sintered Ag/AgCl (RE) placed in adjacent soft tissue | − 1.8 V for 1 h ± 5 wk of vancomycin dosing | Combining the application of − 1.8 V for 1 h with a prolonged 5-week course of vancomycin, remarkably, 80% of the animals had no MRSA CFU detectable on the implant nor bone tissue. This was in contrast to the prevalent bacterial burden present on the implant and in the bone tissue for animals in the no treatment control group and those animals that received the prolonged vancomycin without CVCES. Histology showed stimulation had no deleterious effect of the bone tissue |
*Note that WE is the working electrode, CE is the counter electrode, and RE is the reference electrode