Antibacterial efficacy of zinc oxide nanoparticles on Proteus mirabilis: MIC, MBC, and comparative analysis with conventional antibiotics

Abstract

Catheter-associated urinary tract infections (CAUTI) attributable to colonisation and infection by Proteus mirabilis are a pressing issue owing to their ability to form crystalline biofilms that obstruct urinary catheters. In this study, we evaluated the antibiofilm activity of zinc oxide nanoparticles (ZnONPs) against P. mirabilis and compared it to conventional antibiotics. ZnONPs were characterised by energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) to assess their morphology, size and surface characteristics, key determinants of their antimicrobial efficacy. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ZnONPs were 125 μg/mL and 175 μg/mL, respectively, with up to 99.7% bacterial growth inhibited. The results show that ZnONPs possess concentration-dependent antibacterial activity, often exceeding the effectiveness of standard antibiotics. The superior activity of ZnONPs is associated with their high surface area-to-volume ratio, which enhances their interactions with bacterial membranes. These findings demonstrate that ZnONPs are a promising alternative for treating P. mirabilis biofilms in CAUTIs, particularly in antibiotic-resistant cases. The potential clinical applications of this research include the development of ZnONP-based treatments for CAUTIs and the design of novel strategies to combat antibiotic resistance, highlighting the necessity for further research on their synergistic potential and clinical applications.