Enterococcus hirae-Mediated ZnO and CuO/ZnO Nanoparticles: Synergistic Antimicrobial Combinations Against MDR...

Area of Science:

• Nanotechnology and Materials Science
• Microbiology and Infectious Diseases
• Environmental Science and Green Chemistry

Background:

• The rise of multidrug-resistant (MDR) pathogens, especially in hospital wastewater, presents a significant global health challenge.
• There is an urgent need for novel antimicrobial strategies to combat these resistant infections.
• Extracellular biosynthesis of nanoparticles offers a sustainable and environmentally friendly approach to developing new therapeutic agents.

Purpose of the Study:

• To synthesize zinc oxide nanoparticles (ZnO NPs) and copper oxide/zinc oxide nanoparticles (CuO/ZnO NPs) using the environmentally derived strain *Enterococcus hirae*.
• To characterize the synthesized nanoparticles and evaluate their antimicrobial and antioxidant activities.
• To investigate the synergistic effects of these nanoparticles with conventional antibiotics against MDR pathogens.

Main Methods:

• Extracellular green synthesis of ZnO NPs and CuO/ZnO NPs using *Enterococcus hirae*.
• Comprehensive characterization of nanoparticles using UV-Vis, XRD, FTIR, FE-SEM, TEM, and EDS.
• Antimicrobial activity assessed via MIC and MBC assays; antioxidant activity evaluated using DPPH assay; synergistic effects with antibiotics tested against MDR isolates.

Main Results:

• Successful synthesis and characterization of ZnO NPs and CuO/ZnO NPs confirmed by various spectroscopic and microscopic techniques.
• CuO/ZnO NPs demonstrated significantly enhanced antimicrobial efficacy (62.5% greater than ZnO NPs) and superior antioxidant activity (IC50 of 5.528 μg/mL).
• Synergistic interactions were observed between the synthesized nanoparticles and antibiotics (ciprofloxacin, ceftazidime), particularly against *Klebsiella pneumoniae*.

Conclusions:

• The study successfully demonstrated the effective *E. hirae*-mediated synthesis of CuO/ZnO NPs with enhanced antibacterial and antioxidant properties.
• These eco-friendly nanoparticles represent a promising strategy to combat MDR infections.
• The observed synergistic effects with conventional antibiotics highlight the potential of these nanoparticles to improve treatment efficacy, especially against challenging pathogens like *K. pneumoniae*.