M Al-Rawi - Department of Medical Microbiology, College of Medicine, Al-Iraqia University, Baghdad, Iraq
N. H. A. L Al-Mudallal - Department of Medical Microbiology, College of Medicine, Al-Iraqia University, Baghdad, Iraq
A. A Taha - Department of Applied Science, Division of Biotechnology, University of Technology, Baghdad, Iraq

The improvement of multi-resistance properties of the bacterial pathogen has recently been discussed as an emerging issue. In this regard, iron oxide nanoparticles have attracted the researchers’ attention due to their wide application in the realm of medicine. Iron oxide nanoparticles have a high specific surface area that enables them to interact with the bacterial surface structure and has considerable antibacterial activity. The current study aimed to synthesize a novel antimicrobial agent from iron oxide nanoparticles and determine its minimum inhibitory concentration (MIC) on different gram-positive and negative variant bacterial strains isolated and characterized from the infected urinary tract of Iraqi elderly patients. This study was conducted from September ۲۰۲۰ to December ۲۰۲۰ on ۷۵ urine samples collected from the infected urinary tract of elderly patients in the ages range of ۶۰-۷۵ years admitted to Al-Yarmouk Medical Hospital, Baghdad, Iraq. Isolation of bacterial isolates was carried out using differential and selective media. Afterward, they were characterized and confirmed using different biochemical tests and VITEK ۲ system, respectively. Magnetic nanoparticles were fabricated by co-precipitation of ferric ions (Fe۳+) and ferrous ions (Fe۲+) in presence of ammonium hydroxide solution (۲۵%). The characterization of synthesized nanoparticles was performed subsequently using UV-VIS spectroscopy analysis, Scanning Electron Microscope (SEM), Fourier transform infrared spectroscopy analysis, X-ray Diffraction analysis (XRD), and Energy-dispersive X-ray spectrum (EDX). The MIC of synthesized sonicated Fe۳O۴NP against different bacterial strains was determined using the broth culture dilution method through making serial dilutions of ۵۰, ۱۰۰, ۲۰۰, ۴۰۰, ۵۰۰, ۶۰۰, ۸۰۰, ۹۰۰ µg/ml from a ۵mg/ml nanoparticle stock solution. Afterward, the lowest concentration of nanoparticles required to arrest the growth of bacteria was determined through the colony-forming unit of each treated bacteria on brain heart infusion agar. In total, ۱۷bacterial isolates were identified from the infected urinary tract, five bacterial isolates (E. coli, Pseudomanas aeruginosa, Staphylococcus aureus, Enterococcus faecalis, and Micrococcus luteus). In addition, two Proteus mirabilis strains were identified separately and were tested against synthesized Fe۳O۴NP to determine the MIC. The novel synthesized antibacterial agent showed excellent bioactivity, compared with controls (consisting of bacterial suspension without ferrous oxide nanoparticles), and the synthesized antibacterial agent was considered significantly active against all the bacterial strains at a p-value less than ۰.۰۵. The Fe۳O۴NP were active against gram-negative more than gram-positive bacteria. The MIC of synthesized and characterized Fe۳O۴NPwas applied on seven gram-positive and negative bacterial isolates using bacteria- Fe۳O۴NP complex. Significant effects were observed on all strains, compared with controls, and this complex could significantly inhibit gram-negative more than gram-positive bacteria.

Iron Oxide Nps, Bacterial Strains, Uti Elderly Patients, Minimum Inhibitory Concentration