Document Type : Research Article
Authors
1
Department of Microbiology Plant Pathology, Ji.c., Islamic Azad University, Jiroft, Iran
2
Department of Plant Pathology, Ji.c., Islamic Azad University, Jiroft, Iran
3
Jiroft Social Security Clinic, Jiroft, Iran
4
Crop and Horticultural Science Research Department, South Kerman Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Jiroft, Iran
5
Department of Environmental Health Engineering, Tehran University of Medical Science, Tehran, Iran
6
Agronomy and Plant Breeding Department, Faculty of Agriculture, Yasouj University, Yasouj, Iran
7
Department of Agronomy and Plant Breeding, Agriculture Institute, Research Institute of Zabol, Zabol, Iran
Abstract
E. coli’s TEM gene-mediated resistance to beta-lactams challenges UTI treatment. This study explores oleander-synthesized silver nanoparticles as a novel antimicrobial strategy against resistant strains. To assess TEM gene prevalence in E. coli isolates and evaluate oleander-based AgNPs and methyltransferase interactions for combating antibiotic resistance. A total of 155 UTI-associated E. coli isolates were identified via biochemical tests and ESBL screening (CLSI guidelines). TEM gene detection used PCR with specific primers. Oleander-synthesized AgNPs were characterized (UV-Vis) and tested for antimicrobial activity (disk diffusion, MIC/MBC). Protein-protein docking analyzed blaTEM (KX462012.1) and oleander methyltransferase (MH504111.1) interactions. Experimental data analyzed via randomized ANOVA, Duncan's test (p<0.05), PFAFFL. Among 155 E. coli isolates from UTIs, 65% (100 strains) produced ESBLs, with highest resistance to ampicillin (74%), carbenicillin (61%), and chloramphenicol (53%). PCR confirmed the blaTEM gene in 60% of tested isolates. Oleander-synthesized silver nanoparticles (AgNPs) exhibited potent antimicrobial activity, showing dose-dependent inhibition zones (10–40 µg/mL), with MIC and MBC values of 16 µg/mL and 32 µg/mL, respectively. Real-time PCR revealed a 48.5% reduction in blaTEM expression (*p* < 0.05) after AgNP treatment. Molecular docking demonstrated stable binding between blaTEM and oleander methyltransferase, driven by hydrophobic interactions (Leu, Ile, Val, Phe, Trp), with Trp playing a pivotal role. Ramachandran plots validated high-quality 3D structures (94–96% favored residues) for both proteins. The study isolated 155 E. coli strains (65% ESBL-producing) from UTIs, showing high antibiotic resistance. Oleander-synthesized silver nanoparticles (MIC: 16 µg/mL) inhibited TEM gene-carrying E. coli and reduced TEM expression by 48.5%. Oleander methyltransferase stably binds blaTEM via hydrophobic interactions, validated by high-quality 3D modeling and docking studies.
Keywords
Main Subjects
)