Electric Current-Induced Detachment of Staphylococcus epidermidis Biofilms from Surgical Stainless Steel

Abstract

Biomaterial-centered infections of orthopedic percutaneous implants are serious complications which can ultimately lead to osteomyelitis, with devastating effects on bone and surrounding tissues, especially since the biofilm mode of growth offers protection against antibiotics and since removal frequently is the only ultimate solution. Recently, it was demonstrated that as a possible pathway to prevent infections of percutaneous stainless steel implants, electric currents of 60 to 100 A were effective at stimulating the detachment of initially adhering staphylococci from surgical stainless steel. However, initially adhering bacteria are known to adhere more reversibly than bacteria growing in the later stages of biofilm formation. Hence, the aim of this study was to examine whether a growing Staphylococcus epidermidis biofilm can be stimulated to detach from surgical stainless steel by the use of electric currents. In separate experiments, four currents, i.e., 60 and 100 A of direct current (DC) and 60 and 100 A of block current (50% duty cycle, 1 Hz), were applied for 360 min to stimulate the detachment of an S. epidermidis biofilm that had grown for 200 min. A 100-A DC yielded 78% detachment, whereas a 100-A block current under the same experimental conditions yielded only 31% detachment. The same trend was found for 60 A, with 37% detachment for a DC and 24% for a block current. Bacteria remaining on the surface after the current application were less viable than they were prior to the current application, as demonstrated by confocal laser scanning microscopy. In conclusion, these results suggest that DCs are preferred for curing infections.

Electrical methods of controlling bacterial adhesion and biofilm on device surfaces

“…The same group would later show that DC current applied for 6 h was much more effective at detaching 200 minute biofilms (grown on the electrode surface by circulating tryptic soy broth for 200 minutes following the aforementioned rinsing of planktonic bacteria with buffer) from stainless steel surfaces than AC applied for the same duration [65]. Results have demonstrated that direct currents are effective at and much better than alternating currents for detaching Staphylococcus epidermidis biofilms on orthopedic implants.…”

“…Limitations of conductive polymers are generally due to manufacturing costs, material variation, toxicity, poor solubility in solvents and inability to directly melt the polymer. However, when used as a very thin surface layer on a catheter for example [102], they are as effective as indium tin oxide [65]. Composite materials such as silicones mixed with silver or nickel particles could offer the best possible solution at present for implementing some of the most promising recent electrical bacterial control strategies in an IMD [30,69,85] Silver nanoparticles embedded in a polymer matrix deposited using plasma polymerization could form a conductive polymer with inherent antibacterial properties [103].…”

“…Low-electric currents ranging from 15 µA up to 125 µA (1.5-1.7 V) have been used to successfully detach bacterial strains of Staphylococcus epidermidis and Staphylococcus aureus from surgical stainless steel anode surfaces within a parallel plate flow chamber [60]. Bacteria were introduced to the chamber in a flowing suspension of physiological ionic strength and following adherence to the stainless steel surface; the suspension was switched for a solution of specified ionic strength containing no bacteria.…”

Cathodic Voltage-controlled Electrical Stimulation Plus Prolonged Vancomycin Reduce Bacterial Burden of a Titanium Implant-associated Infection in a Rodent Model

“…This could be the result of disruption of the biofilm to release bacteria in the more vulnerable planktonic form or through a molecular or microenvironmental mechanism that is currently unknown. Although there have been numerous in vitro reports on the antimicrobial effects of direct electrical simulation with or without combination with antibiotics [3,6,8,9,17,18,24], there are only a few in vivo reports [7,13,23]. In contrast to the other in vivo models using electrical stimulation to treat implant-associated infections [7,13,23], CVCES uses a three-electrode configuration that allows us to precisely control the cathodic potential of the titanium implant [10,11].…”

Technological Development in Therapeutic Applications of Alternating Electric Fields: Review

“…However, the extensive use of antibiotics holds a threat in the future due to the rapid rise of multi drug resistant bacteria. Recently, a number of alternative modes like weak electric currents [1,2,3,4], ultrasound wave therapy [5,6,7] , thermotherapy [8], photodynamic therapy [9] have been studied. These are expected to aid the antibiotics in the battle against bacterial pathogens.…”