Augmentation of antibiotic activity by low-frequency electric and electromagnetic fields examining Staphylococcus aureus in broth media

Abstract

Systemic treatment of biomaterial-associated bacterial infections with high doses of antibiotics is an established therapeutic concept. The purpose of this in vitro study was to determine the influence of magnetic, electromagnetic, and electric fields on gentamicin-based, antibiotic therapy. It has been previously reported that these fields are successful in the treatment of bone healing and reducing osteitis in infected tibia-pseudarthroses. Four separate experimental setups were used to expose bacterial cultures of Staphylococcus aureus both in Mueller-Hinton broth (MHB) and on Mueller-Hinton agar (MHA), in the presence of gentamicin, to (1) a low-frequency magnetic field (MF) 20 Hz, 5 mT; (2) a low-frequency MF combined with an additional alternating electric field (MF + EF) 20 Hz, 5 mT, 470 mV/cm; (3) a sinusoidal alternating electric field (EF AC) 20 Hz, 470 mV/cm; and (4) a direct current electric field (EF DC) 588 mV/cm. No significant difference between samples and controls was detected on MHA. However, in MHB each of the four fields applied showed a significant growth reduction of planktonically grown Staphylococcus aureus in the presence of gentamicin between 32% and 91% within 24 h of the experiment. The best results were obtained by a direct current EF, decreasing colony-forming units (CFU)/ml more than 91%. The application of electromagnetic fields in the area of implant and bone infections could offer new perspectives in antibiotic treatment and antimicrobial chemotherapy.

Cathodic Electrical Stimulation Combined With Vancomycin Enhances Treatment of Methicillin-resistant Staphylococcus aureus Implant-associated Infections

“…Although there have been numerous in vitro reports on the antimicrobial effects of direct electrical simulation with or without combination with antibiotics [2,9,11,12,[21][22][23]32], there are only a few in vivo reports. Using a rabbit model of osteomyelitis with Staphylococcal epidermidis, it was shown that a constant current of 200 lA delivered to an intramedullary stainless steel electrode for 21 days produced a 1.5 order of magnitude reduction in bacteria when compared with the use of doxycycline alone [10].…”

Evaluation of the effects of Extremely Low Frequency (ELF) Pulsed Electromagnetic Fields (PEMF) on survival of the bacterium Staphylococcus aureus

“…The importance of this study is attributed to the emergence of drug resistant bacteria. Clinical studies show beneficial use of PEMF therapy, and thus suggest integration of this form of therapy into the standard of care in inhibiting Staphylococcus aureus infections and hence, augmenting antibiotic therapy [42,43]. We investigated the effects of the generated ELF PEMF on the bacterium S. aureus in broth cultures and conclude that magnetic flux densities in the range of 0.5-2.5 mT for 2-500 Hz resulted in the decrease of the number of live cells (CFU) in all irradiated samples when compared to the controls.…”

The Effect of Rotating Magnetic Field on Enterotoxin Genes Expression in Staphylococcus Aureus Strains

“…It is assumed that the MFs interact initially with the cell membrane, activating signal transduction pathways that lead to the nucleus and result in stress protein synthesis [4]. It was also shown that various types of the MFs can influence on functional processes in microorganisms, including their pathogenicity potential [5,6]. Similarly, to eukaryotic cells, also bacteria (e.g.…”