en Anti-microbial agents, resistance and treatment protocols Anti-microbial agents, resistance and treatment protocols Original article Original article <span style="font-size:11pt"><span style="line-height:normal"><span sans-serif="" style="font-family:Calibri,"><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Introduction:</span></span></b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times=""> Increased multidrug-resistant (MDR) <i>Acinetobacter baumannii</i> infections pose a significant challenge in hospital settings. Enhanced resistance to antibiotics like fluoroquinolones and &beta;-lactams necessitates adopting alternative treatment strategies such as metal oxide nanoparticles<a name="_Hlk155169806">. This study investigated the synergistic effect of zinc oxide nanoparticles (ZnO-NPs) on ciprofloxacin and ceftazidime activity against MDR <i>A. baumannii</i>.</a> <b>Methods:</b> We examined 30 MDR <i>A. baumannii</i> 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)</span></span> <span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">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. <b>Results:</b> ZnO-NPs combined with ciprofloxacin 8 &mu;g/mL and ceftazidime 32 &mu;g/mL exhibited inhibition growth percentage (GI%) increases of 44.9% and 31.65%.&nbsp; <b>Conclusion:</b> The enhanced <i>in vitro</i> antibacterial effects of combined ZnO-NPs and antibiotics against MDR <i>A. baumannii</i> indicate a synergy. Considering the limited number of isolates, comprehensive research incorporating <i>in vivo</i> models and clinical trials is warranted to evaluate the practicality of this approach in overcoming antibiotic resistance. </span></span></span></span></span><br> <br> &nbsp; Acinetobacter baumannii, Zinc oxide nanoparticles, Ciprofloxacin, Ceftazidime 192 199 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-541-1&slc_lang=en&sid=1 Nader Mashayekh mashayekh.nader.50@gmail.com No Department of Microbiology, Faculty of Biological Sciences, Islamic Azad University, Mazandaran, Tonekabon, Iran Leila Modiri modirii.leila@gmail.com 0000-0002-2133-5796 Yes Department of Microbiology, Faculty of Basic Sciences, Lahijan Branch, Islamic Azad University, Lahijan, Iran Masood Ghane masood.ghane@iau.ac.ir 0000-0003-4257-1584 No Department of Microbiology, Faculty of Basic Sciences, Lahijan Branch, Islamic Azad University, Lahijan, Iran Yousef Erfani Yerfani@sina.tums.ac.ir 0000-0002-0508-8123 No Department of Medical Laboratory Sciences, School of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran