Exposure to Extremely Low-Frequency Magnetic Field Affects Biofilm Formation by Cystic Fibrosis Pathogens

Giovanni Di Bonaventura; Arianna Pompilio; Valentina Crocetta; Serena De Nicola; Filippo Barbaro; Livio Giuliani; Enrico D'Emilia; Ersilia Fiscarelli; Rosa Grazia Bellomo; Raoul Saggini

Disclosures

Future Microbiol. 2014;9(12):1303-1317. 

In This Article

Abstract and Introduction

Abstract

Aims To evaluate the in vitro effects of extremely low-frequency magnetic field (ELF-MF) on growth and biofilm formation by Staphylococcus aureus, Pseudomonas aeruginosa, Burkholderia cepacia and Stenotrophomonas maltophilia strains from cystic fibrosis patients.

Materials & Methods The motion of selected ions (Fe, Ca, Cu, Zn, Mg, K, Na) was stimulated by the ion resonance effect, then influence on growth and biofilm formation/viability was assessed by spectrophotometry or viability count.

Results Generally, exposure to ELF-MF significantly increased bacterial growth and affected both biofilm formation and viability, although with differences with regard to ions and species considered.

Conclusion Exposure to ELF-MF represents a possible new approach for treatment of biofilm-associated cystic fibrosis lung infections.

Introduction

Pseudomonas aeruginosa, Burkholderia cepacia and Staphylococcus aureus are the most common bacterial pathogens isolated from the airways of cystic fibrosis (CF) patients where they cause chronic infections responsible for high morbidity and mortality.[1,2] However, the extensive use of antipseudomonal antibiotic therapy exerted a relevant selective pressure on pulmonary bacterial populations recently leading to an increasing number of reports involving potentially emerging and challenging pathogens.[3] This is the case of multidrug-resistant Stenotrophomonas maltophilia whose isolation from CF airways is recently reported with increasing prevalence and incidence.[3,4]

Physicians treating CF patients are increasingly faced with infections caused by multidrug-resistant strains. Efforts are also hampered by the high microbial adaptation to the CF pulmonary environment, resulting in an increased ability to form biofilms, sessile communities embedded in a self-produced extracellular polymeric substance (EPS), intrinsically resistant to antibiotics as well as toward the host immune defense.[5]

Novel strategies that could replace or complement current therapies are, therefore, needed to counteract chronic infections in CF patients.

Magnetic fields are widely used in medicine, in diagnostic (i.e., MRI) as well as in therapeutic (i.e., magnetic stimulation of brain areas, magnetic drug targeting, treatment of pressure ulcers and bone regeneration) practices.[6–8] The rationale for these applications comes from the results obtained in several studies designed to explore the interaction between extremely low-frequency magnetic fields (ELF-MF) and more complex biochemical structures, such as enzymes, amino acids, protein, genes and DNA.[9–13] The plausibility of these interactions derives from the discovery of the inner structure of water, one of the consequences of the quantum electrodynamics.[14,15]

Recently, exploiting the 'Liboff–Zhadin effect'[16–20] in order to develop a biotechnology based on the modulation of ion currents, within the cytoplasm and through the cell membrane, ELF-MF have been applied to induce maturation and differentiation of stem cells[21–23] or tumor cells,[24,25] and to treat heart failures, tumors or degenerative age-dependent diseases.[26] Furthermore, we recently provided the first validation for clinical use of external pulsed electromagnetic fields in the rehabilitative treatment for lower back pain.[27]

In recent years, several studies were focused on the interaction between weak magnetic fields and living systems in the frame of microbiology. In this regard, particular attention has been recently given to bactericidal effects associated to magnetic field exposure.[28–32] However, despite the antibacterial effect of magnetic field exposure against planktonic cells being extensively investigated, the effect on the bacterial adhesion and its subsequent growth as biofilms remains significantly unexplored. In this regard, at the best of our knowledge, there is no available literature dealing with the effect of electromagnetic fields on CF pathogens.

The purpose of this work was, therefore, to determine for the first time whether application of ELF-MF could influence growth and biofilm formation by Gram-positive (S. aureus) and Gram-negative (P. aeruginosa, B. cepacia and S. maltophilia) pathogens causing chronic lung infections in CF patients. Thus, we used a device properly designed for in vitro experiments at room conditions able to produce a sequence of weak ELF-MF, each one tuned with ion cyclotronic resonance (ICR) frequencies related to specific metal ions.

Overall, our results showed that exposure to ELF-MF, despite stimulating bacterial growth, significantly reduces biofilm formation thus suggesting it could be relevant to consider this technique for preventing CF chronic lung infections.

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