Broad spectrum antimicrobial nanoparticles with low toxicity to prevent biofilm formation on urologic devices.

Antimicrobial coatings for medical implants are critical in preventing device failures and infections. Antibiotics are often used as prophylactic or coatings but fail to prevent biofilm formation and drive antibiotic resistance. Herein, the antibacterial and antibiofilm activities of different polyhydroxy fullerene-based metal nanoparticle coatings on polyurethane discs were quantified after exposure to Escherichia coli. Gold-silver nanoparticles (GSNP) exhibited superior antibacterial activity compared to other silver-containing nanoparticles. GSNPs were evaluated against Escherichia coli, Enterococcus faecalis, Enterobacter hormaechei, Klebsiella oxytoca, Staphylococcus aureus and Staphylococcus epidermidis isolated from ureteral stents and inflatable penile prostheses and achieved 100% reduction of all tested urologic pathogens at physiological relevant bacterial loads (p < 0.0001). GSNPs inactivate bacteria by reactive oxygen species production with the estimated minimum inhibitory concentrations slightly higher for Gram-positive than Gram-negative bacteria with highest observed for S. epidermidis at 2.23 µg/mL. Safety studies with fibroblasts demonstrate that GSNPs at estimated minimum inhibitory concentrations have minimal effect (< 20%) on cell viability. Further, the GSNPs were able to reduce bacteria by six logs more than commercial nanoparticles. GSNPs represent a promising strategy for preventing biofilm formation on medical devices and implants due to their broad antibacterial activity and low toxicity.