Effects of prolonged exposure to moderate static magnetic field and its synergistic effects with alkaline pH on Enterococcus faecalis. (February 2018)

• Record Type: Journal Article
• Authors: Fan, Wei; Huang, Zhuo; Fan, Bing
• Is Part Of: Microbial pathogenesis. Volume 115(2018)
• Page Start: 117
• Page End: 122
• Publication Date: 2018-02
• Subjects: Static magnetic field -- Alkaline pH -- Antimicrobial activity -- Stress response -- Virulence gene -- Biofilm formation; Pathogenic microorganisms -- Periodicals; Pathology, Molecular -- Periodicals; Communicable Diseases -- microbiology -- Periodicals; Communicable Diseases -- parasitology -- Periodicals; Micro-organismes pathogènes -- Périodiques; Pathologie moléculaire -- Périodiques; Electronic journals; 616.9041
• DOI: 10.1016/j.micpath.2017.12.028
• Languages: English
• ISSNs: 0882-4010

Abstract

Abstract: Static magnetic field (SMF) has been shown to biologically affect various microorganisms, but its effects on Enterococcus faecalis, which is associated with multiple dental infections, have not been reported yet. Besides, Enterococcus faecalis was found to be resistant to the alkaline environment provided by a major dental antimicrobial, calcium hydroxide. Therefore, the antibacterial activity of prolonged exposure to moderate SMF (170 mT) and its possible synergistic activity with alkaline pH (pH = 9) were evaluated in the study. The ability to form a biofilm under these conditions was examined by crystal violet assay. Real-time quantitative PCR was performed to evaluate the relative expression of stress (dnaK and groEL) and virulence (efaA, ace, gelE and fsrC) related genes. As the results indicated, cell proliferation was inhibited after 120 h of SMF exposure. What's more, the combined treatment of SMF and alkaline pH showed significantly improved antimicrobial action when compared to single SMF and alkaline pH treatment for more than 24 h and 72 h respectively. However, the ability to form a biofilm was also enhanced under SMF and alkaline pH treatments. SMF can induce stress response by up-regulating the expression of dnaK and elevate virulence gene expression (efaA and ace). These responses were more significant and more genes were up-regulated including groEL, gelE and fsrC when exposed to SMF and alkaline pH simultaneously. Hence, combination of SMF and alkaline pH could be a promising disinfection strategy in dental area and other areas associated with Enterococcus faecalis infections. Highlights: Antimicrobial effect of moderate static magnetic field against E. faecalis was revealed. The synergistic antibacterial effect of moderate static magnetic field and alkaline pH was firstly confirmed. Static magnetic field exposure induced stress response of E. faecalis. Virulence related genes were up-regulated under static magnetic field and alkaline pH stresses.