The Synergistic Effect of Plant-Derived Silver Nanoparticles and Antibiotics on Resistance Genes in Escherichia Coli

Introduction & Objective: blaTEM-related Escherichjsoninsoula coli is seriously equipotent to multi-drugs resistance, and the synthesized silver nanoparticles (AgNPs) using plants are emerging as an alternative approach for overcoming this menace. To assess the combined effect of AgNPs (obtained from Thyme) and classical antibiotics on growth and blaTEM gene frequency in E. coli.

Materials & Method: A total of 127 urine samples from pregnant women were collected and tested for E. coli, confirmed 73 isolates. Susceptibility to antibiotics was performed by Vitek and disc diffusion. The AgNPs were prepared from Thymus vulgaris, and these nanoparticles were evaluated for their UV–Vis, FTIR, SEM/TEM characterization 25, 50, 75, and 100 μg/mL by agar well diffusion assay. Pre- and post-AgNP treatment, blaTEM was detected by PCR.

Results: Of 127 urine samples, 73 (57.5%) were identified as E. coli. All isolates were biochemically identical. With antibiotics, there was 100% susceptibility to Netilmicin and Aztreonam, but Tobramycin and Piperacillin were almost totally resistant (1.4% SEN., 4.1% SEN.). MDR, XDR and EDR patterns were 62/73 (84.9%), 7/73 (9.6%) and 4/73 (5.5%) respectively. Initially, all 14 isolates (100%) were found to possess the blaTEM gene. Thyme-mediated silver nanoparticles (AgNPs) were prepared (average particle size ~21.5 nm) and the trend of dose-dependent inhibition: 25 μg/mL: 8.2 mm, 50 g μg/ml: 12.5 mm, 75 μg ml -1 :16.8 mm, 100 μg/mL landing up with a mean inhibition zone of as high as21.3mm. blaTEM positivity was reduced to 7/14 of the isolates (50%) after treatment with AgNP, indicating potent inhibition of resistance gene.

Conclusion: Thyme-capped AgNPs in combination with antibiotics were effective at decreasing the growth of E. coli and blaTEM prevalence and may serve as a potential intervention against entire multidrug resistant isolates.