Electrical enhancement of Pseudomonas aeruginosa biofilm killing by the antibiotic tobramycin.  The y-axis is a measure of the enhancement of killing in the antibiotic plus electric current case compared to the antibiotic alone case.  A weak direct current (Standard) increases killing by almost 3 decades.  When the wires are placed outside the box such that the same electrical field is established, but without current flow (No Current), no enhancement was observed.  When oxygen was sparged during antibiotic treatment, with no current flow, a 2 log enhancement was observed.  Sparging hydrogen had no effect.  We interpret this to indicate that electrolytic generation of oxygen may partially explain the electrical enhancement of biofilm killing, the so-called "bioelectric effect."  See Stewart et al., 1998 in our Resource Library collection of abstracts.