Bactericidal effect of magnesium ions over planktonic and sessile Staphylococcus epidermidis and Escherichia coli

Magnesium and its alloys are in focus to produce implants due to their excellent mechanical properties, facility to decompose in the body, enhancement of new bone formation and antibacterial properties. However, there is still a lack of consensus about the origin of such antibacterial effect. Up to date, most antibacterial studies were performed over newly synthesized MgO particles, nanotubes or nanowires in the form of slurries, integrated within polymeric matrixes or as coatings of other bulk materials whereas the effect of pure Mg2+ ions over bacteria viability, in the absence of secondary processes, has not been assessed yet. Hence, in this study, we have characterized the bactericidal effect of Mg2+ ions over two different bacteria strains, Staphylococcus epidermidis (Gram-positive) and Escherichia coli (Gram-negative) controlling both pH and ion concentration. Also, we have considered the ion effect on dissimilar planktonic and sessile cells on surfaces with different hydrophobicity.