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

Abstract

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.

Alanine racemase is essential for the growth and interspecies competitiveness of Streptococcus mutans

“…18 Approximately 10 mL of cell culture was harvested by low-speed centrifugation (3 000 g , 10 min), washed twice in 200 mmol̇L −1 sodium cacodylate buffer, pre-fixed with 2.5 ġL −1 glutaraldehyde and fixed with 10 ġL −1 OsO 4 . Samples were embedded in Epon resin, and thin sections (60 nm) were prepared using a microtome.…”

Electroactive 3D Printed Scaffolds Based on Percolated Composites of Polycaprolactone with Thermally Reduced Graphene Oxide for Antibacterial and Tissue Engineering Applications

“…The mechanism of the effect of electric current on bacterial cells are not yet fully understood, although it is associated with changes in the medium through: generation of biocidal ions and reactive oxygen species (ROS), pH modification, and electrophoretic forces [24,25]. It has been shown that DC can be used to modulate bacterial detachment and movement on conductive surfaces [26][27][28][29][30][31]. Negatively charged bacteria were electrically manipulated by modulating the electrophoretic movements under DC, inducing an antiadhesive effect [26].…”

A Novel In Vitro System for Comparative Analyses of Bone Cells and Bacteria under Electrical Stimulation

“…Several studies over the last years focused on ES of bacteria to prevent bacterial growth and biofilm formation [19–28]. Not only staphylococci but also Escherichia coli as well as Pseudomonas aeruginosa were investigated and tested using ES in different experimental set-ups [19–23]. Despite investigating and applying different types of electrical stimulation (e.g., direct current, alternating current, electromagnetic stimulation, or pulsed currents), the underlying effects of electrical stimulation, as well as effects on a more molecular level instead of macroscopic disruption of bacteria, still have to be elucidated.…”