Evaluation of antibacterial activity of zinc oxide nanoparticles against biofilm producing methicillin resistant Staphylococcus aureus (MRSA)
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Nanotechnology is an interdisciplinary platform, where a broad range of nanosize materials is being developed for novel and innovative applications. Nanomaterials possess properties that are not found in the bulk form, thereby giving the nanomaterials and enhanced physicochemical and biological properties, as well as functionalities. Having an adequate amount of Zn in the body is crucial for the protein and DNA synthesis, optimal functioning of immune response and metalloenzyme function. Antibacterial activity of zinc oxide nanoparticles (ZnO-NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize particles in the nanometer region. Particular emphasize was given to bactericidal and bacteriostatic mechanisms with focus on generation of reactive oxygen species (ROS) including hydrogen peroxide (H2O2), OH-(hydroxyl radicals), and O2−2 (peroxide). ROS has been a major factor for several mechanisms including cell wall damage due to ZnO localized interaction, enhanced membrane permeability, internalization of NPs due to loss of proton motive force and uptake of toxic dissolved zinc ions. These have led to mitochondria weakness, intracellular outflow, and release in gene expression of oxidative stress which caused eventual cell growth inhibition and cell death. Staphylococcus aureus is a nosocomial human pathogen. Approximately 30% of the human population is colonized with S. aureus. Simultaneously, it is a leading cause of bacteremia, skin and soft tissue and pleura pulmonary infections. Out of 200 strains of S. aureus isolated from clinical samples, 50 were found to be methicillin resistant respectively. Morbidity and mortality rates due to methicillin-resistant Staphylococcus aureus (MRSA) infection are increasing, so studies in controlling these infection is gravely required. Key step in this process is the identification of virulence determinants that may serve as targets for vaccine and drug development. The biofilm production is an important phenomenon by bacteria such as Staphylococcus aureus that contribute to the multiple drug resistance. MIC and MBC values of Zinc oxide nanoparticles against isolated Methicillin-resisitant. MRSA strains were observed very low, i.e. in the range of 312.5, 625 μg/ml and 1250 μg/ml, respectively; which is indicating very good bactericidal activity. Zn-NPs with highest concentration showed almost no growth for upto 24 hrs, This representing a bactericidal effect at this concentration. Effect was proportional to dose since 1875 μg/ml was the most effective treatment (the bacterial population did not recover) and 312.5 μg/ml was the least effective.
MRSA, Zinc oxide nanoparticle, Biofilm, MIC, MBC and antibacterial activity.