Assessment of antimicrobial potential of green zinc oxide nanoparticles (ZnONPs) of Bacopa monnieri (L.) against clinical isolates of Escherichia coli

Antimicrobial resistance (AMR) is a major global health issue caused by the overuse of antibiotics across various sectors. It leads to the emergence of resistant microorganisms and could surpass other leading causes of death by 2050. Escherichia coli, commonly used as an indicator organism for monitoring AMR in livestock and food products from animals, naturally inhabits the intestines of warm-blooded animals. This study aims to utilize Bacopa monnieri (L.) extract as a reducing and stabilizing agent for synthesizing ZnONPs through green synthesis and to test their antimicrobial activity against clinical isolates of multidrug-resistant E. coli. The green synthesized ZnONPs were characterized chemically, optically, and morphologically using techniques such as UV-VIS Spectrophotometry, FTIR Spectroscopy, and TEM. Additionally, E. coli isolated from mucous samples was characterized morphologically, biochemically, and molecularly using gram-staining, MacConkey agar differential media test, oxidase test, and PCR based molecular confirmation. Later, antimicrobial assay was performed using MIC technique. The presence of the Surface Plasmon Resonance peak in UV-VIS spectra confirmed the successful synthesis of ZnONPs, while FTIR spectra indicated the presence of functional groups associated with phytochemicals involved in the bioreduction process during ZnONPs formation. TEM analysis revealed the development of nanoparticles with small dimensions. Furthermore, green-synthesized ZnONPs of Bacopa monnieri (L.) demonstrated promising antimicrobial activity, with a MIC of 316.4 mg/mL against MDR E. coli.