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

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.