Bactericidal activity of gallium-doped chitosan coatings against staphylococcal infection

Aims: The aim of this study was to develop a new class of gallium (Ga)-doped chitosan (CS) coatings fabricated by electrophoretic deposition (EPD) in staphylococcal infection therapy. Methods and Results: Biofilm formation on EPD CS/Ga coatings by Staphylococcus epidermidis and Staphylococcus aureus, which are the main strains involved in postarthroplasty infections, was assessed. The codeposition of an antibacterial agent was effective; Ga loaded into CS matrix reduces biofilm viability by up to 86% and 80% for S. epidermidis and S. aureus strains respectively. Lastly, the influence of pulsed electromagnetic field (PEMF) on the bactericidal activity of CS/Ga coatings was investigated in vitro. To this end, the coatings were incubated with S. epidermidis and S. aureus and exposed to the PEMF using two different frequencies and times. Biofilm viability for S. epidermidis was decreased by 35–40% in the presence of low-frequency (LF) and high-frequency (HF) PEMF respectively. Biofilm viability by S. aureus was not further reduced in the presence of LF PEMF, but decreased by 38% at HF PEMF. Conclusions: This study has established that a combination of PEMFs with the antibacterial agent improves bactericidal activity of Ga against S. epidermidis strain 14990 and S. aureus strain 12600. Significance and Impact of the Study: This new integrated approach could reduce the incidence of infection in orthopaedic implant applications. It also clearly demonstrates that the combination of Ga treatment with PEMF could aid biofilm-associated infection therapy due to improved Ga efficiency.