Eco-friendly drugs induce cellular changes in colistin-resistant bacteria

Background and objective ‒ As a last option, multidrug-resistant Gram-negative infections (caused by Enterobacteriaceae) are treated with the antibiotic colistin, also known as polymyxin E. Colistin-resistant superbugs predispose people to untreatable infections, possibly leading to a high mortality rate. This project aims to study the effect of Acacia nilotica aqueous extract and zinc oxide nanoparticles (ZnO-NPs) on colistin-resistant Klebsiella pneumonia (CRKP). Materials and methods ‒ ZnO-NPs were synthesized using the green method and characterized by UV-vis, Fourier transform infrared spectroscopy, and X-ray diffraction. The zone of inhibition (ZI) was measured using the agar-well diffusion method, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration were estimated to determine the antimicrobial activity of the tested compound. Scanning electron microscopy (SEM) and transmission electronic microscopy (TEM) were used to investigate the alterations in bacterial cells that were treated with the tested drugs. Results ‒ The synthesized ZnO-NPs presented good chemical and physical properties, and the plant extract and ZnO-NPs displayed a large ZI. ZnO-NPs had the lowest MIC (0.2 mg·mL⁻¹). SEM and TEM observations revealed various morphological modifications in CRKP cells, including cell shrinkage, cell damage, cytoplasm loss, cell wall thinning, and cell death. Conclusion ‒ A. nilotica aqueous extract and ZnO-NPs could be used as alternative natural products to produce antibacterial drugs and to prevent CRKP infection.