Colloidal suspension of polyphenolic nanoparticles as a novel strategy to combat antimicrobial resistance

As anticipated and feared for a long time, antimicrobial resistance has been worsening, and nowadays many bacterial infections cannot be controlled by a simple antibiotic administration. A new and innovative approach to combat this global threat is necessary. The resistance to antimicrobials spreads between animals, environment and humans which makes it even more challenging to deal with. A One Health approach must be adopted and improved. Polyphenolic compounds have been explored due to their potential ability to inhibit microbial growth; however, some downsides have been connected to their use, such as low water solubility, bioavailability, and instability. Existing shortcomings of polyphenols could be overcome by implementing nano-based approach, that could result in enhanced bioavailability, controlled drug-release and targeting, and lower degradation. In this project, the efficacy of polyphenolic nanoparticles as a potential alternative to conventional antimicrobials was investigated. A stable colloidal suspension consisting of polyphenolic nanoparticles were produced by top-down synthesis from waste product of the wood industry. A panel of six bacteria (i.e., Escherichia coli, Mannhemia haemolytica, Pasteurella multocida, Salmonella typhimurium, Staphylococcus aureus, Streptococcus suis) known for their zoonotic and resistant potential were included in this study. Minimum Inhibitory Concentration (MIC) was performed in order to assess the compounds antimicrobial activity. Nanoparticle dilutions with a concentration ranging from 15mg/L to 0.46875 mg/L were tested against 5 log CFU/mL of the bacteria inoculum. The optical density (OD600) was measured, and a threshold of < 0.05 absorbance was adopted to determine the minimum inhibitory concentration. Our results indicated that these nanoparticles showed different effects based on the specific bacteria tested, effectively inhibiting microbial growth at notably low concentrations of M. haemolytica (3,75 mg/L) and P. multocida (15 mg/L). Polyphenolic nanoparticles tested demonstrate potent antimicrobial capabilities, suggesting promising applications in livestock production. By replacing conventional antimicrobials, they could mitigate the prevalence of antimicrobial resistance.