Dataset Information

Silver Nanoparticles at Biocompatible Dosage Synergistically Increases Bacterial Susceptibility to Antibiotics.

ABSTRACT: Antibiotics used to treat bacterial infections can become ineffective over time or result in the emergence of antibiotic resistant pathogens. With the advent of nanotechnology, silver nanoparticles (AgNPs) have gained significant attention as a therapeutic agent due to the well-known antimicrobial properties of silver. However, there are concerns and limited literature on the potential cytotoxicity of nanoparticles at effective antimicrobial concentrations. AgNPs prepared from silver nitrate with glucose reduction were characterized by surface plasmon resonance, dynamic light scattering, zeta potential analysis and transmission electron microscopy. The cytotoxicity of AgNPs towards human gingival fibroblasts over 7 days was determined using cell proliferation assays and confocal microscopy. AgNP MIC and antibacterial effects alone and in combination with 11 antibiotics were determined against a panel of nine microbial species including gram-positive and gram-negative bacterial species. AgNPs concentrations ? 1 ?g/mL were non-cytotoxic but also showed no antibacterial effects. However, when combined with each of eleven antibiotics, the biocompatible concentration of AgNPs (1 ?g/mL) resulted in significant inhibition of bacterial growth for multiple bacterial species that were resistant to either the antibiotics or AgNPs alone. This study presents a promising strategy with further testing in vivo, to develop novel antimicrobial agents and strategies to confront emerging antimicrobial resistance.

SUBMITTER: Ipe DS

PROVIDER: S-EPMC7326045 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Silver Nanoparticles at Biocompatible Dosage Synergistically Increases Bacterial Susceptibility to Antibiotics.

Ipe Deepak S DS Kumar P T Sudheesh PTS Love Robert M RM Hamlet Stephen M SM

Frontiers in microbiology 20200527

Antibiotics used to treat bacterial infections can become ineffective over time or result in the emergence of antibiotic resistant pathogens. With the advent of nanotechnology, silver nanoparticles (AgNPs) have gained significant attention as a therapeutic agent due to the well-known antimicrobial properties of silver. However, there are concerns and limited literature on the potential cytotoxicity of nanoparticles at effective antimicrobial concentrations. AgNPs prepared from silver nitrate wit ...[more]

PMID: 32670214

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Project description:Green synthesis of silver nanoparticles (AgNPs) has garnered tremendous interest as conventional methods include the use and production of toxic chemicals, products, by-products and reagents. In this regard, the synthesis of AgNPs using green tea (GT) extract and two of its components, (−)-epigallocatechin gallate (EGCG) and (+)-catechin (Ct) as capping/stabilizing agents, is reported. The synthesized AgNPs showed antibacterial activity against the bacterial strains Staphylococcus aureus and Escherichia coli, along with anticancer activity against HeLa cells. After administering nanoparticles to the body, they come in contact with proteins and results in the formation of a protein corona; hence we studied the interactions of these biocompatible AgNPs with hen egg white lysozyme (HEWL) as a carrier protein. Static quenching mechanism was accountable for the quenching of HEWL fluorescence by the AgNPs. The binding constant (Kb) was found to be higher for EGCG-AgNPs ((2.309 ± 0.018) × 104 M−1) than for GT-AgNPs and Ct-AgNPs towards HEWL. EGCG-AgNPs increased the polarity near the binding site while Ct-AgNPs caused the opposite effect, but GT-AgNPs had no such observable effects. Circular dichroism studies indicated that the AgNPs had no such appreciable impact on the secondary structure of HEWL. The key findings of this research included the synthesis of AgNPs using GT extract and its constituent polyphenols, and showed significant antibacterial, anticancer and protein-binding properties. The –OH groups of the polyphenols drive the in situ capping/stabilization of the AgNPs during synthesis, which might offer new opportunities having implications for nanomedicine and nanodiagnostics. Graphical abstract Image 1 Highlights • Green tea and its constituent polyphenols can effectively reduce Ag+ ion to AgNPs.• Synthesized AgNPs could bind to HEWL and quench its intrinsic fluorescence.• Binding of AgNPs with HEWL was found to be spontaneous in nature.• AgNPs showed promising anti-bacterial effects against E. coli and S. aureus.• Biocompatible AgNPs showed enhanced cytotoxicity towards HeLa cells.

Project description:Bacterial keratitis is a serious and vision-threatening condition in veterinary and human patients, one that often requires culture and susceptibility testing to adjust therapy and improve clinical outcomes. The present study challenges the antimicrobial susceptibility testing (AST) paradigm in ophthalmology, enabling more accurate in vitro-to-in vivo translation by incorporating factors normally present during host-pathogen interactions in clinical patients. Thirty bacteria (10 Staphylococcus pseudintermedius, 10 Streptococcus canis, 10 Pseudomonas aeruginosa) were isolated from canine patients with infectious keratitis. For each isolate, commercial plates (Sensititre™ JOEYE2) were used to assess the minimal inhibitory concentration (MIC) of 17 different antibiotics in the absence (0% albumin, control) or presence of canine albumin (0.01-2%). For Staphylococcus pseudintermedius, the experiment was repeated with actual tear fluid collected from canine eyes with ocular surface inflammation. Kruskal-Wallis, Wilcoxon signed rank test and Spearman's correlation tests were used for statistical analysis. Clinical outcomes were unfavorable in selected canine patients with bacterial keratitis (e.g., globe perforation, graft dehiscence) despite standard AST (i.e., 0% albumin in test medium) confirming that most corneal infections (93%) were susceptible to ≥1 topical antibiotics used at the initial visit. Albumin levels ≥0.05% increased MICs in a dose-dependent, bacteria-specific, and antibiotic-specific manner. No significant differences (P = 1.000) were noted in MICs of any antibiotic whether albumin or tear fluid was added to the Mueller-Hinton broth. Percent protein binding inherent to each antibiotic was associated with clinical interpretations (Spearman's rho = -0.53, P = 0.034) but not changes in MICs. Albumin in tears impacted the efficacy of selected ophthalmic antibiotics as only the unbound portion of an antibiotic is microbiologically active. The present findings could improve decision making of clinicians managing bacterial keratitis, reduce development of antimicrobial resistance, influence current guidelines set by the Clinical and Laboratory Standards Institute, and serve as a reference for bacteriological evaluations across medical fields and across species.

Dataset Information

Silver Nanoparticles at Biocompatible Dosage Synergistically Increases Bacterial Susceptibility to Antibiotics.

Publications

Silver Nanoparticles at Biocompatible Dosage Synergistically Increases Bacterial Susceptibility to Antibiotics.

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