Antibacterial Activity of Lactobacillus reuteri–Mediated Biosynthesized Silver Nanoparticles Against Multidrug-Resistant Bacterial Isolates from Burn and Ulcer Wounds: An In Vitro Study
DOI:
https://doi.org/10.63939/qz3pv668Keywords:
Antibiotics, Multiple drug resistance (MDR), Burn injuries Synergistic effect, Lactobacillus reutter, green synthesis, silver nanoparticles (AgNPs), Ulcerative woundsAbstract
Background: Burns and ulcerative wounds are high-risk sites for multidrug-resistant bacterial infections. Silver nanoparticles synthesized using Lactobacillus reuteri bacteria may offer an environmentally friendly and sustainable alternative with potent antibacterial activity. Objective: "This study represents a scientific effort to evaluate the inhibitory efficacy of silver nanoparticles (AgNPs) synthesized via a green pathway, using Lactobacillus reuteri as both reducing agent and biological carrier, against clinically isolated antibiotic-resistant bacteria from burn and ulcer wounds. Methodology: Isolates were obtained from patients at Al-Hussein Medical City's hospital laboratory in Karbala, Iraq, during October 2024 to March 2025. The study was grounded in the hypothesis that integrating Lactobacillus's biological properties—as part of normal flora, producing organic acids and bacteriocins—with silver nanoparticles' unique physicochemical traits would yield a synergistic effect capable of overcoming complex bacterial resistance mechanisms.". The practical aspect of the research involved collecting twenty clinical swabs from infection sites and transferring them to sterile media to ensure accurate retrieval of bacterial isolates. Critical bacterial strains were identified, including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter. Their identity and resistance patterns were confirmed through a series of biochemical and susceptibility tests according to the Clinical Laboratory Standards Institute (CLSI) criteria. This was followed by the biosynthesis of nanoparticles, utilizing the reducing capacity of naturally occurring Lactobacillus
reuteri to convert silver ions into nanoparticles. These nanoparticles were then characterized using UV-Vis spectroscopy to determine the absorption peak and electron microscopy to verify the size distribution and morphology of the resulting particles. Results: The expression levels of resistance genes were assessed, and silver nanoparticles (AgNPs) were found to inhibit the growth of all tested multidrug-resistant (MDR) bacterial strains. The diameters of the inhibition zones (MZs) (mm) at concentrations of 15, 20, and 25 µg/ml were as follows: Staphylococcus aureus 24.0–27.0, vancomycin-resistant Enterococcus 21.0–26.0, Acinetobacter baumannii 19.0–23.0, Pseudomonas aeruginosa 17.0–22; Klebsiella pneumoniae 16–18 mm; Escherichia coli 13–17 mm. The minimum inhibitory concentration (MIC) ranged between 15 and 25 µg/ml. Gram-positive bacteria were more susceptible than Gram-negative bacteria. The observed differences were statistically significant between species and concentrations (p<0.05). Results: Traditional antibiotics showed varying sensitivity, with some Armenian Protestant strains showing resistance to all classes of drugs tested. Conclusions: This proves that this green nanotechnology approach represents a promising and low-cost strategic alternative to address the escalating microbial resistance crisis in clinical settings.
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