Antimicrobial Behavior of Zinc Oxide Nanoparticles and β-Lactam Antibiotics against Pathogenic Bacteria

Background: Multi-drug resistance among the pathogenic bacteria poses a serious threat to public health. Nanoparticles are one of the most effective therapeutic agents. Zinc oxide nanoparticles (ZnO NPs) are well known antimicrobial agents and are regarded as nontoxic and bio-safe. The present study aims to investigate the antimicrobial effect of ZnO NPs against the bacterial strains i.e. Klebsiella pneumoniae (K. pneumoniae) and Escherichia coli (E.coli). Methodology: The antibacterial activity was performed by Kirby’s Disc diffusion assay using different concentrations (0.2, 0.4, 0.6, 0.8 and 1.0) mg/ml of ZnO NPs with and without β lactam antibiotics (Ciprofloxacin and Imipenem). The Minimum inhibitory concentration (MIC) was evaluated through the standard agar dilution method. Antioxidant potential of ZnO NPs was analyzed through αα-diphenyl-βpicrylhydrazyl (DPPH) radical scavenging activity while the Cytotoxicity of ZnO NPs was evaluated through Brine shrimp lethality assay. Results: The results revealed that the highest zone of inhibition was more in K. pneumoniae i.e. 27.2 mm as compared to E.coli i.e. 13.2 mm. The MIC value for K. pneumoniae and E.coli was 0.05 mg/ml and 0.08 mg/ml respectively. Antioxidant potential of ZnO NPs increases as the concentration of NPs was increased. However, the cytotoxicity analysis showed the non-toxic effect of ZnO NPs. Conclusion: The results indicated that ZnO NPs possess strong antimicrobial activity and can enhance the antimicrobial activity of some beta-lactam antibiotics. The present study can be helpful to formulate nano-drug conjugates as antimicrobial agents in various fields of medical and pharmaceutical research.