The growth of Staphylococcus aureus and Escherichia coli in low-direct current electric fields

• Published in: International journal of oral science 2014-03, Vol.6 (1), p.7-14
• Main Authors: Zituni, Dunya, Schütt-Gerowitt, Heidi, Kopp, Marion, Krönke, Martin, Addicks, Klaus, Hoffmann, Christian, Hellmich, Martin, Faber, Franz, Niedermeier, Wilhelm
• Format: Article
• Language: English
• Subjects: 631/326/41; 692/308; Bacterial Load - radiation effects; Bacteriological Techniques; Caseins; Cell Wall - radiation effects; Culture Media; Cytoplasm - radiation effects; Dentistry; Electricity; Escherichia coli; Escherichia coli - growth & development; Escherichia coli - radiation effects; Gels; Humans; Medicine; Microbial Viability - radiation effects; Microscopy, Electron, Transmission; Oral and Maxillofacial Surgery; Original; original-article; Orthopedics; Protein Hydrolysates; Sodium Chloride; Staphylococcus aureus; Staphylococcus aureus - growth & development; Staphylococcus aureus - radiation effects; Surgical Orthopedics; Water
• ISSN: 1674-2818; 2049-3169
• DOI: 10.1038/ijos.2013.64

Electrical potentials up to 800 mV can be observed between different metallic dental restorations. These potentials produce fields in the mouth that may interfere with microbial communities. The present study focuses on the impact of different electric field strengths (EFS) on the growth of Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922) in vitro . Cultures of S. aureus and E. coli in fluid and gel medium were exposed to different EFS. Effects were determined by calculation of viable counts and measurement of inhibition zones. In gel medium, anodic inhibition zones for S. aureus were larger than those for E. coli at all field strength levels. In fluid medium, the maximum decrease in the viable count of S. aureus cells was at 10 V⋅m −1 . Field-treated S. aureus cells presented ruptured cell walls and disintegrated cytoplasm. Conclusively, S. aureus is more sensitive to increasing electric field strength than E. coli. Oral microbes: mixed alloys have electrifying effects The bacterium Staphylococcus aureus is more sensitive than Escherichia coli to disruption by low-voltage currents, researchers in Germany have found. Dental restorations made of different alloys can generate a direct, or galvanic, current in the mouth that is conducted through saliva. Typically, bacteria are negatively charged, so galvanic currents can alter their growth and behavior. Dunya Zituni and co-workers at Cologne University investigated the effect of low-voltage currents with electrical field strength of 2–27 V⋅m −1 on cultures of the common oral microbe S. aureus and the model organism E. coli. In solid medium, the currents inhibited larger zones of S. aureus than E. coli ; and, in liquid culture, they ruptured a larger percentage of S. aureus ’s cells. The researchers conclude that dental restorations should consist of one alloy only to avoid altering oral microbial communities.