(279a) Control of Pseudomonas Aeruginosa Biofilms By Electrical Currents Using a Simple Agar Model

Electroceutical wound dressings show promise for treating biofilm infections, however, the mechanism of action is poorly understood. We developed an in vitro agar based wound infection model using a bioluminescent strain of Pseudomonas aeruginosa to measure loss of activity and killing when direct current was applied to silver electrodes overlaid with agar. A 6V battery with 1kΩ ballast resistor was used to expose the biofilms to the electric current for 1h and 24h. Loss of bioluminescence and a 4-log reduction in cells was achieved over the anode. Scanning electron microscopy showed that the biofilm had been disrupted and cells showed evidence of lysis. Even after turning off the current the antimicrobial activity continued to spread from the anode for 3 days suggesting generation of a stable antimicrobial agent had occurred. Elevated levels of chloride in the agar and chlorotyrosine in the dead biofilm suggested a role for hypochlorous acid. Similar killing was obtained for biofilms grown on gels containing onlybovine synovial fluid or human serum. We hypothesize that in the presence of physiological fluids, hypochlorous acid is produced at the anode which may react with proteins in the agar and/or the biofilm to form stable reactive intermediates.