Background: The abilities to form biofilm and produce several virulence factors have caused numerous human pathogens to become tremendously resistant towards traditional antibiotic treatments, thus, new alternative strategies are urgently demanded. One of the strategies that has recently been developed involves the nanoparticles (NPs) based on metal NPs. Up to the present, promising results in terms of antimicrobial and antibiofilm activities have been observed in a wide range of metal NPs.
Objective: The present study has selected several metal oxides such as ZnO, SnO2 and CeO2 NPs to investigate their antibiofilm and antibacterial properties against two Gram positive human pathogens which are Listeria monocytogenes and Staphylococcus aureus.
Method: The anti-biofilm activity of ZnO, SnO2 and CeO2 NPs against Listeria monocytogenes and Staphylococcus aureus were assayed by crystal violet staining and confirmed by microscopic visualization using Sem and fluorescence microscope. The production of amyloid protein by Staphylococcus aureus and exopolysaccharide (EPS) of Listeria monocytogenes in the presence of ZnO, SnO2 and CeO2 NPs were evaluated by Congo Red assay.
Result: Results have shown that ZnO, SnO2 and CeO2 NPs effectively inhibited biofilm formation of both L. monocytogenes and S. aureus. Microscopic analysis also confirmed the antibiofilm activity of these NPs. In addition, ZnO NPs inhibited the cell growth as well as the production of amyloid protein in S. aureus.
Conclusion: Overall, these results indicated that ZnO, SnO2 and CeO2 NPs can be considered as potential agents for treating the infections caused by L. monocytogenes and S. aureus, especially those associates with the bacterial biofilm formation. In addition, since this is the first study to report about these effects for ZnO, SnO2 and CeO2 NPs, further studies are required in order to understand their mechanisms at both phenotypic and molecular levels, as well as their in vivo cytotoxicity, thereby enabling the applications of these metal oxide NPs in biomedical fields and food industry.