Thymol-based Chitosan Nanogels Have Strong Antibacterial and Anti-biofilm Effects on Multidrug-resistant Pathogens

Abstract Introduction: The discovery of antibiotics for the treatment of bacterial infections was one of the most important advances in medical history, but unfortunately bacteria are highly adaptable, and overuse of antibiotics has made many bacteria resistant to antibiotics. In the present study, the antibacterial and antibiofilm effects of Thymol-based chitosan nanogels were investigated.Materials & Methods:After clinical screening of MDR strains from the hospital environment, the morphological characteristics of the synthesized nanoparticles were identified using SEM, DLS, XRD and FTIR and the efficiency of encapsulation, stability and drug release were evaluated. After determining the MIC concentration of nanoparticles, the expression of OmpA and PgaB biofilm genes were determined by q-Real-Time PCR and the antibacterial and cytotoxic properties of the nanoparticles were determined by well diffusion and MTT methods, respectively.Results:Three bacteria Pseudomonas, Acinetobacter and Staphylococcus were identified as MDR strains and the antibacterial and antibiofilm properties of nanoparticles with a size of 82.71 nm, encapsulation efficiency of 76.54% and stability up to 60 days at 4 °C were evaluated. The results of the biological study showed strong antibacterial properties of Thymol-based chitosan nanoparticles by reducing the expression of OmpA and PgaB biofilm genes at a significant level of P ≤ 0.05 and reducing antibiotic resistance compared to the free drug thymol and chitosan nanogels. Thymol-based chitosan nanogels at concentrations of 0.125 to 256μg/mL showed the lowest cytotoxicity against HEK-293 compared to chitosan and free Thymol nanogels.Discussion and Conclusion: The results of the study showed the very strong antibacterial properties of Thymol-based chitosan nanogels against MDR strains such as Staphylococcus, Acinetobacter and Pseudomonas as the challenging bacteria of the century. Therefore, the use of Thymol-based chitosan nanogels can be reported as a new application strategy with high potential in the pharmaceutical industry.