The effect of ZnO nanoparticles on bacterial load of experimental infectious wounds contaminated with Staphylococcus aureus in mice

Objective (s): Bacterial infection is an important cause of delayed wound healing. Staphylococcus aureus (S. aureus) is the main agent causing these infections. Zinc Oxide (ZnO) nanoparticles have antibacterial activity and also accelerate the wound healing process. The aim of the present study is to evaluate the effect of ZnO nanoparticles on bacterial load reduction of the wound infection. Materials and Methods: Broth dilution method was used to determine MIC. The MIC of ZnO nanoparticles was determined 125 μg/ml. ZnO nanoparticles had a bacteriostatic effect against S. aureus and inhibited bacterial growth in in vitro. Thirty six mice were prepared and divided into three groups. Skin wound created on the back of all of them, the bacterial suspension (106 CFU of S. aureus) inoculated to each wound site and finally, three groups were treated with 40 μl of ZnO nanoparticles, tetracycline, and normal saline respectively. Results: Superficial and depth bacterial load were determined on days 7, 14, 21. The results showed that bacterial load reduction of ZnO nanoparticles group was significantly different with the negative control group (p<0.05). Significant reduction of the deep bacterial load was observed in the ZnO nanoparticles group comparing to control group on day 21 (p< 0.05). Conclusion: The present results showed that the topical application of ZnO nanoparticles is very effective in the bacterial load reduction. Based on our findings the ZnO nanoparticles may reduce the bacterial load of wound infection so will accelerate the wound healing