Antimicrobial potential of gallium nitrate against Staphylococcus aureus: inhibition of planktonic growth and biofilm formation on titanium surfaces

Abstract

Hospital-acquired infections remain a significant concern in modern healthcare, particularly those resulting from invasive medical procedures. According to the World Health Organization (2020), a considerable proportion of hospitalized patients contract infections during their stay. Among the leading causative agents, Escherichia coli and Staphylococcus aureus have been extensively reported as major contributors to these infections. Over time, these bacteria have developed resistance to multiple antibiotics, limiting treatment options and emphasizing the need for innovative antimicrobial strategies. Gallium (Ga³⁺) has emerged as a promising alternative due to its physicochemical similarity to iron (Fe³⁺), which enables it to disrupt bacterial metabolic processes. This property allows gallium to interfere with the growth of both planktonic bacteria and biofilms. In this study, serial microdilution assays were conducted to determine the minimum inhibitory concentration (MIC) of gallium nitrate (Ga(NO₃)₃) required to inhibit E. coli and S. aureus. The findings revealed that bacterial growth was significantly reduced at concentrations of 11.25 μM for E. coli and 1.40 μM for S. aureus. These results indicate that even low concentrations of Ga(NO₃)₃ effectively suppressed the proliferation of these nosocomial pathogens, demonstrating a potential advantage over previously reported antimicrobial approaches.