Evaluation of Silver Nanoparticles Interaction with Colistin and Antibiotics on Bacterial Isolates from Patients with Diarrhea

Background: Microbial resistance to antibiotics is one of the most critical health risks in our current era, and the development of these antibiotics through their association with agents that support inhibition and are safe for health is one of the recent tendencies in developing these antibiotics and thus eliminating severe diseases that threaten human health and safety. Objectives: This research aimed to determine the Silver nanoparticles (AgNPs) singly or with Colistin and Some antibiotics against the bacterial isolates from patients with diarrhea. Materials and Methods: The AgNPs were biosynthesized using the Cinnamon bark extract and characterized using the change in solution color, Ultra Violet–Visible spectroscopy (UV–VIS), Transmission Electronic Microscope (TEM) and X-ray Diffraction (XRD) techniques, and determine its ability singly or with Colistin peptide combinations with some antibiotics against bacterial isolates Escherichia coli , Salmonella typhimurium , Staphylococcus aureus , and Enterococcus faecalis isolates from patients with diarrhea. Results: The AgNPs characterization was revealed through the color change from pale to deep-brown as well as the absorption peaks appeared at 428 nm using the UV–VIS spectroscopy, which is evidence of the formation of AgNPs, as well as the TEM technique showed the shape of the AgNPs at an average size of 22.8 nm. XRD examination was found to clarify the crystalline properties. The AgNPs and Colistin showed antimicrobial activity by determining the minimum inhibitory concentration and impregnating them with the tested antibiotic discs that were ineffective against bacterial isolates. It was found that there was a partial synergism between AgNPs and Colistin with ceftriaxone and ciprofloxacin for E. coli and S. typhimurium and with vancomycin and tetracycline for S. aureus and E. faecalis . Conclusions: It was concluded that the synergy between AgNPs and Colistin was clear against all isolates used in the study.