Silver and titanium metal nanoparticles as antibacterial to extensive multi-drug-resistant Gram-negative bacteria with down regulation of bacterial virulence factors MagA in Klebsiella pneumonia, and Cfn1 in Acinetobacter baumannii

Background: For several reasons, the rise of MDR bacteria is a serious concern as they are more severe than infections caused by more vulnerable organisms. Our study aims to evaluate antibacterial activity of Ag and TiO2NPs against MDR Gram-negative bacteria. Methods: UV-Vis absorption spectral analysis, transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), and dynamic light scattering (DLS) techniques were used to characterize NPs by examining their optical, morphological structure, and colloidal properties. Antibacterial assay was done through agar well diffusion method. Gene expression of bacterial virulence genes cfn1 and MagA done through RT-PCR. Results: Cubic Ag NPs with size (30±5 nm) & anatase crystal structural TiO₂NPs (20±5 nm) were effective in elimination MDR Gram-negative bacterial grwoth. AgNPs were effective against 16 MDR at 4 µg/mL, while at 8 µg/mL, they were effective against two E. coli strains, Y04 and Y017. TiO₂NPs exhibit a higher MIC than AgNPs; it was 32.5 µg/mL to 5 isolates; other isolates were inhibited at 16.25 µg/mL. Ag was more effective against E. coli Y017 (31mm). TiO₂NPs were most effective on K. pneumonia Y011 (33mm). The most extensive MDR isolates were K. pneumonia Y023 PQ274462.1 & A. baumannii Y025 PQ274461.1. Both cfn1 and MagA decreased by 2.5 µg/mL AgNPs with fold changes of 0.4 and 0.65, respectively, while they recorded 0.66- and 0.88-fold changes by 12.5 µg/mL TiO₂ NPs. Conclusion: Both AgNPs, and TiO2 NPs exhibit antibacterial activity and down regulation of bacterial virulence genes cfn1 and MagA.