Gallium Liquid Metal Nanoparticles as Agents to Treat Multidrug-Resistant Bacterial Infections

Multidrug-resistant (MDR) bacterial infections constitute one of the top global public health threats. This study investigated the potential of gallium liquid metal nanoparticles (GaLM NPs) as a new agent against MDR pathogens. GaLM NPs was bactericidal against methicillin-resistant Staphylococcus aureus (MRSA) isolates and a vancomycin-intermediate S. aureus reference strain (minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values between 39 and 156 μg/mL). The bactericidal activity of GaLM NPs was supported by transmission electron microscopy showing marked ultrastructural changes in the cell envelope of MRSA USA300. GaLM NPs were bacteriostatic against selected Gram-negative (Acinetobacter baumannii, Pseudomonas aeruginosa and Klebsiella pneumoniae) reference strains and isolates (MICs between 39 and 625 μg/mL). Furthermore, GaLM NPs demonstrated additive and bacteriostatic activity when combined with sub-inhibitory concentrations of colistin against P. aeruginosa isolates. Additionally, GaLM NPs showed anti-biofilm activity against MRSA USA300 (minimum biofilm eradication concentration of 625 μg/mL); morphology changes of GaLM NPs-treated cells was demonstrated by scanning electron microscopy. Finally, GaLM NPs was safe to human epidermal keratinocyte cell line at 1024 µg/mL (6.5 × MIC). We conclude that GaLM NPs warrant further exploration for the effective treatment of Gram-positive or Gram-negative infections both alone and in combination with antimicrobial drugs.