Electric block current induced detachment from surgical stainless steel and decreased viability of Staphylococcus epidermidis

Abstract

In vitro studies investigating the influence of electric DC current on bacterial detachment have demonstrated that continuous currents of only 25-125 microA stimulated staphylococcal strains to detach from surgical stainless steel. However, DC currents produce more power that has to be dissipated by the skin as compared to alternating currents. Also, an excess of ions on the steel can cause negative osteogenesis and fixation results. Therefore, it is the aim of this paper to examine whether detachment of Staphylococcus epidermidis from stainless steel surfaces in a parallel plate flow chamber can also be stimulated using electric block currents. Block currents of 15, 60 and 100 microA with different frequencies (0.1-2 Hz) and duty cycles (5-50%) were applied to induce bacterial detachment. Block currents of 100 microA cause detachment of about 76% of adhering staphylococci from stainless steel, whereas in addition the remaining bacteria are less viable, as determined by culturing the remaining bacteria on agar plates. Therewith, block current-induced detachment of adhering bacteria from stainless steel appears to be an equally promising method to prevent infection of orthopaedic fixation pins and screws than application of DC currents.