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Title: Antibacterial activity of low amperage and low voltage electric current (DC)
Author: Liu, Wai-Kin
ISNI:       0000 0004 2675 3406
Awarding Body: Aston University
Current Institution: Aston University
Date of Award: 1997
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The efficacy of a direct electric current (10μA, 9V) via electrode-conducting carbon impregnated catheters to prevent colonisation of catheters by micro-organisms was investigated. The catheters acting as the anode and the cathode were inserted into a nutrient agar plate inoculated with a lawn of bacteria. There was no zone of inhibition observed around the anode. Organisms susceptible to 10μA at the cathode were Staphylococcus aureus (2 strains), Staphylococcus epidermidis (5 strains), Escherichia coli and Klebsiella pneumoniae (2 strains each), and one strain of the following micro-organisms: Staphylococcus hominis, Proteus mirabilis, Pseudomonas aeruginosa and Candida albicans. The mechanisms of the bactericidal activity associated with the cathode were investigated with S. epidermidis and S. aureus. The inhibition zone was created reduced in the presence of catalase. Hydrogen peroxide was produced at the cathode surface under aerobic conditions, but not in the absence of oxygen. A salt-bridge apparatus was used to demonstrate further that hydrogen peroxide was produced at the cathode, and chlorine at the anode. Antibacterial activity was reduced under anaerobic conditions, which is compatible with the role of hydrogen peroxide as a primary bactericidal agent of electricity associated with the cathode. A reduction in chloride ions did not significantly reduce the antibacterial activity. 10μA applied via the catheters did not prevent the initial biofilm growth by the adherent bacteria but reduced the number of bacteria in the biofilm by 2 log order after 24h. The results suggested that 10μA may prevent the colonisation of catheters by both the extra- and intra-luminal routes. The localised production of hydrogen peroxide and chlorine and the intrinsic activity due to electric current may offer a useful method for the eradication of bacteria from catheter surfaces.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: Pharmacology