Antimicrobial Effect of Zinc Oxide Nanoparticles against Multidrug-Resistant Acinetobacter baumannii

Introduction: Increased multidrug-resistant (MDR) Acinetobacter baumannii infections pose a significant challenge in hospital settings. Enhanced resistance to antibiotics like fluoroquinolones and β-lactams necessitates adopting alternative treatment strategies such as metal oxide nanoparticles. This study investigated the synergistic effect of zinc oxide nanoparticles (ZnO-NPs) on ciprofloxacin and ceftazidime activity against MDR A. baumannii. Methods: We examined 30 MDR A. baumannii isolates from intensive care unit (ICU) patients in Iran. ZnO-NPs were synthesized via the solvothermal method and characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) to ascertain their crystalline structure and morphology. Antibacterial activity was evaluated by determining minimum inhibitory concentrations (MICs) and inhibition zones through broth microdilution and disk diffusion methods, using concentrations of ciprofloxacin and ceftazidime in combination with ZnO-NPs. Results: ZnO-NPs combined with ciprofloxacin 8 μg/mL and ceftazidime 32 μg/mL exhibited inhibition growth percentage (GI%) increases of 44.9% and 31.65%.  Conclusion: The enhanced in vitro antibacterial effects of combined ZnO-NPs and antibiotics against MDR A. baumannii indicate a synergy. Considering the limited number of isolates, comprehensive research incorporating in vivo models and clinical trials is warranted to evaluate the practicality of this approach in overcoming antibiotic resistance.