Iontophoretic killing of Escherichia coli in static fluid and in a model catheter system

A static iontophoretic model system was used to determine the effects of various metals, microamperage (μA) levels, and voltage levels on Escherichia coli and several other bacterial genera. Only gold iontophoresis at 400 μA and approximately 3.2 V was found to kill all bacterial genera tested when the inoculum dose was 1 x 10³ cells per ml. E. coli was killed at all inocula doses to 1 x 10⁷, whereas other genera were inhibited. Other metals, such as silver or copper, were not effective in killing bacteria. A model catheter system, which contained a gold iontophoresis device, was used to kill E. coli in a flowing system at sites as far as 10 cm downstream from the iontophoretic device. The experiments suggest gold iontophoresis can be a potential tool in controlling catheter-related infections.