Background: The ability to form biofilm and produce several virulence factors has caused
numerous human pathogens to become tremendously resistant towards traditional antibiotic treatments,
thus, new alternative strategies are urgently in demand. One of the strategies that have recently been developed
involves the application of metallic Nanoparticles (NPs). Up to the present, promising results in
terms of antimicrobial and antibiofilm activities have been observed in a wide range of metal NPs.
Methods: The present study has selected three metal oxides such as ZnO, SnO2 and CeO2 NPs to comparatively
investigate their antibiofilm and antibacterial properties against two Gram-positive human
pathogens, which are Listeria monocytogenes and Staphylococcus aureus.
Results: The anti-biofilm activities of ZnO, SnO2 and CeO2 NPs against S. aureus and L. monocytogenes
were assayed by crystal violet staining and confirmed by microscopic visualization using SEM.
The synthesis of amyloid protein by S. aureus and exopolysaccharide by L. monocytogenes in the presence
of ZnO, SnO2 and CeO2 NPs was evaluated by Congo red assay.
Discussion: Results have shown that ZnO, SnO2 and CeO2 NPs effectively inhibited biofilm formation
of both L. monocytogenes and S. aureus. The microscopic analysis also confirmed the antibiofilm activity
of these NPs. It was also found that only ZnO NPs inhibited 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 associated
with biofilm formation. Based on the present study, further studies are required 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.