Antibacterial Effect of Zinc Oxide Nanoparticles on Acinetobacter Baumannii Isolated from Patients with Hospital Acquired Infections in Sohag University Hospitals, Egypt

Acinetobacter baumannii (A. baumannii) is Gram- negative, aerobic, glucose non-fermentative, non-motile coccobacillus, ubiquitous in nature, and persistent in healthcare settings. It is regarded as a significant opportunistic human pathogen. This bacterium become a growing problem in hospitals as a predominant multidrug-resistant (MDR) bacterium. Horizontal acquisition of resistance genes is the main factor involved in the emergence of MDR . There are many mechanisms to confer resistance to different classes of antibiotics in A. baumannii, one of them is multidrug efflux pumps. These efflux pumps are important source of MDR, which export antibiotics from the cell, increasing their antibiotic resistance. AdeABC is one of the most important efflux systems, belonging to the RND family in Acinetobacter, which plays an important role in the resistance to a broad group of antibiotics; its genes are chromosomal and encode three genes, i.e., AdeB, AdeA, and AdeC, forming an operon in the vicinity. In addition, the expression of AdeABC is done by a two-component system, which includes a response regulator (AdeR) and a sensor kinase (AdeS) . The ability of Acinetobacter spp. to form biofilm that enables bacterial survival in hospital settings, especially in ICUs, is the most significant contributing factor to their virulence, and this trait is also responsible for their notable antibiotic resistance. Several biofilm-related genes influence antimicrobial susceptibility, suggesting an association between the biofilm-forming ability of Acinetobacter spp. and their antibiotic resistance patterns (MDR/XDR) Zinc oxide nanoparticles (ZnO NPs) are one of the most important nanoparticles of metal oxides; it is a unique and inorganic materials that can be used in several biological applications (anti-bacterial, anti-inflammatory). ZnO NPs exhibit distinctive properties other than other nanoparticles such as higher solubility, better biofilm penetration and effective drug delivery . ZnO NPs have been reported to have antimicrobial properties such as disrupting the cell membrane of pathogens, accumulating in the cell and producing toxic H2O2 (hydrogen peroxide)