Study on the therapeutic index and synergistic effect of Chitosan-zinc oxide nanomicellar composites for drug-resistant bacterial biofilm inhibition

Evaluation of bactericidal effects of silver hydrosol nanotherapeutics against Enterococcus faecium 1449 drug resistant biofilms

Introduction

Silver (Ag) nanoparticles (NPs) are well documented for their broad-spectrum bactericidal effects. This study aimed to test the effect of bioactive Ag-hydrosol NPs on drug-resistant E. faecium 1449 strain and explore the use of artificial intelligence (AI) for automated detection of the bacteria.

Methods

The formation of E. faecium 1449 biofilms in the absence and presence of Ag-hydrosol NPs at different concentrations ranging from 12.4 mg/L to 123 mg/L was evaluated using a 3-dimentional culture system. The biofilm reduction was evaluated using the confocal microscopy in addition to the Transmission Electronic Microscopy (TEM) visualization and spectrofluorimetric quantification using a Biotek Synergy Neo2 microplate reader. The cytotoxicity of the NPs was evaluated in human nasal epithelial cells using the MTT assay. The AI technique based on Fast Regional Convolutional Neural Network architecture was used for the automated detection of the bacteria.

Results

Treatment with Ag-hydrosol NPs at concentrations ranging from 12.4 mg/L to 123 mg/L resulted in 78.09% to 95.20% of biofilm reduction. No statistically significant difference in biofilm reduction was found among different batches of Ag-hydrosol NPs. Quantitative concentration-response relationship analysis indicated that Ag-hydrosol NPs exhibited a relative high anti-biofilm activity and low cytotoxicity with an average EC50 and TC50 values of 0.0333 and 6.55 mg/L, respectively, yielding an average therapeutic index value of 197. The AI-assisted TEM image analysis allowed automated detection of E. faecium 1449 with 97% ~ 99% accuracy.

Discussion

Conclusively, the bioactive Ag-hydrosol NP is a promising nanotherapeutic agent against drug-resistant pathogens. The AI-assisted TEM image analysis was developed with the potential to assess its treatment effect.

The Potential of Antibiotics and Nanomaterial Combinations as Therapeutic Strategies in the Management of Multidrug-Resistant Infections: A Review

Antibiotic resistance has become a major public health concern around the world. This is exacerbated by the non-discovery of novel drugs, the development of resistance mechanisms in most of the clinical isolates of bacteria, as well as recurring infections, hindering disease treatment efficacy. In vitro data has shown that antibiotic combinations can be effective when microorganisms are resistant to individual drugs. Recently, advances in the direction of combination therapy for the treatment of multidrug-resistant (MDR) bacterial infections have embraced antibiotic combinations and the use of nanoparticles conjugated with antibiotics. Nanoparticles (NPs) can penetrate the cellular membrane of disease-causing organisms and obstruct essential molecular pathways, showing unique antibacterial mechanisms. Combined with the optimal drugs, NPs have established synergy and may assist in regulating the general threat of emergent bacterial resistance. This review comprises a general overview of antibiotic combinations strategies for the treatment of microbial infections. The potential of antibiotic combinations with NPs as new entrants in the antimicrobial therapy domain is discussed.

Nanomaterials-Based Combinatorial Therapy as a Strategy to Combat Antibiotic Resistance

Since the discovery of antibiotics, humanity has been able to cope with the battle against bacterial infections. However, the inappropriate use of antibiotics, the lack of innovation in therapeutic agents, and other factors have allowed the emergence of new bacterial strains resistant to multiple antibiotic treatments, causing a crisis in the health sector. Furthermore, the World Health Organization has listed a series of pathogens (ESKAPE group) that have acquired new and varied resistance to different antibiotics families. Therefore, the scientific community has prioritized designing and developing novel treatments to combat these ESKAPE pathogens and other emergent multidrug-resistant bacteria. One of the solutions is the use of combinatorial therapies. Combinatorial therapies seek to enhance the effects of individual treatments at lower doses, bringing the advantage of being, in most cases, much less harmful to patients. Among the new developments in combinatorial therapies, nanomaterials have gained significant interest. Some of the most promising nanotherapeutics include polymers, inorganic nanoparticles, and antimicrobial peptides due to their bactericidal and nanocarrier properties. Therefore, this review focuses on discussing the state-of-the-art of the most significant advances and concludes with a perspective on the future developments of nanotherapeutic combinatorial treatments that target bacterial infections.

Chitosan oligomer and zinc oxide nanoparticles for treating wastewaters: US20190134086 patent evaluation

With the utilisation of algae, wastewater reuse is becoming a viable option for the energy industry, especially green energy. The growth of these algae in these wastewaters provides an alternative source for bioenergetics, however, the growth of other microorganisms can directly affect the production of bioenergy, requiring the removal and reduction of contaminants in these waters, in addition to being a source of contamination for workers. Therefore, the use of nanoparticles in bioremediation has been an alternative to mitigate the contamination of these wastewaters that have microorganisms capable of reducing the algae growth capacity. The objective of this work was to verify in the United States Patent and Trademarker office database (USPTO) patents that used chitosan nanoparticles as a form of wastewater treatment and to carry out the analysis of patent US20190134086, which addresses the use of zinc oxide nanoparticles associated with chitosan that was developed and used to evaluate their antibacterial activity against resistant microorganisms and biofilm producers present in wastewater. Escherichia coli, Enterococcus faecium, and/or Pseudomonas aeruginosa are the microorganisms involved in the evaluated invention, bacteria present in the gastrointestinal tract, of clinical and environmental importance. The synthesized nanoparticles are arranged as a pharmaceutically acceptable and toxic vehicle against resistant bacteria, thus being described as nanoremediators. Given the analyzed patent, it was possible to verify the importance of alternatives to reduce the impact that pollution, in general, has on the environment, in addition to the proposed technology serving to maintain the survival and development capacity of the algae that will be able to produce green energy, the nanoparticles with antibacterial potential can help indirectly reduce these pathogenic strains with resistance to several antibiotics in the environment.

Combinatorial therapy of chitosan hydrogel-based zinc oxide nanocomposite attenuates the virulence of Streptococcus mutans

Background

Biofilm formation is an important causative factor in the expansion of the carious lesions in the enamel. Hence, new approaches to efficient antibacterial agents are highly demanded. This study was conducted to evaluate the antimicrobial-biofilm activity of chitosan hydrogel (CS gel), zinc oxide/ zeolite nanocomposite (ZnONC) either separately or combined together [ZnONC / CS gel (ZnONC-CS)] against Streptococcus mutans biofilm.

Results

MTT assay demonstrated that the ZnONC-CS exhibits a non-cytotoxic effect (> 90% cell viability) toward human gingival fibroblast cells at different dosages (78.1–625 μg/mL) within 72 h. In comparison with CS gel and ZnONC, ZnONC-CS was superior at biofilm formation and metabolic activity reduction by 33 and 45%, respectively; (P < 0.05). The field emission scanning electron microscopy micrographs of the biofilms grown on the enamel slabs were largely in concordance with the quantitative biofilm assay results. Consistent with the reducing effect of ZnONC-CS on biofilm formation, the expression levels of gtfB, gtfC, and ftf significantly decreased.

Conclusions

Taken together, excellent compatibility coupled with an enhanced antimicrobial effect against S. mutans biofilm has equipped ZnONC-CS as a promising candidate for dental biofilm control.

A Streamlined Study on Chitosan-Zinc Oxide Nanomicelle Properties to Mitigate a Drug-Resistant Biofilm Protection Mechanism

The nosocomial multidrug resistant bacteria (MDR), are rapidly circulating from water surfaces to humans away from the clinical setting, forming a cyclical breeding ground of resistance, causing worldwide infections, and thus requiring urgent responses. The combination of chitosan and zinc oxide (CZNPs), with proven bactericidal effects on some MDRs, was further studied to set the stage for a broad-spectrum in vivo utilization of CZNPs. Toward ensuring CZNPs' uniformity and potency, when it faces not only biofilms but also their extracellular polymeric substances (EPS) defense mechanism, the size, zeta potential, and polydispersity index (PDI) were determined through dynamic light scattering (DLS). Furthermore, the efficacy of CZNPs was tested on the inhibition of MDR Gram-negative Escherichia coli BAA-2471 and Gram-positive Enterococcus faecium 1449 models, co-cultured in an Alvatex 3D fiber platform as a biofilm-like structure. The Biotek Synergy Neo2 fluorescent microplate reader was used to detect biofilm shrinkage. The biofilm protection mechanism was elucidated through detection of EPS using 3D confocal and transmission electronic microscopy. Results indicated that 200 μl/mL of CZNPs, made with 50 nm ZnO and 10,000 Da chitosan (N = 369.1 nm; PDI = 0.371; zeta potential = 22.8 mV), was the most promising nanocomposite for MDR biofilm reduction, when compared to CZNPs enclosing ZnO, 18 or 100 nm. This study depicts that CZNPs possess enough potency and versatility to face biofilms' defense mechanism in vivo.

Micro/nanosystems and biomaterials for controlled delivery of antimicrobial and anti-biofilm agents

INTRODUCTION

Microbial resistance is a severe problem for clinical practice due to misuse of antibiotics that promotes the development of surviving strategies by bacteria and fungi. Microbial cells surrounded by a self-produced polymer matrix, defined as biofilms, are inherently more difficult to eradicate. Biofilms endow bacteria with a unique resistance against antibiotics and other anti-microbial agents and play a crucial role in chronic infection.

AREAS COVERED

Biofilm-associated antimicrobial resistance in the lung and wounds. Existing inhaled therapies for treatment of biofilm-associated lung infections. Role of pharmaceutical nanotechnologies to fight resistant microbes and biofilms.

EXPERT OPINION

The effectiveness of antibiotics has gradually decreased due to the onset of resistance phenomena. The formation of biofilms represents one of the most important steps in the development of resistance to antimicrobial treatment. The most obvious solution for overcoming this criticality would be the discovery of new antibiotics. However, the number of new molecules with antimicrobial activity brought into clinical development has considerably decreased. In the last decades the development of innovative drug delivery systems, in particular those based on nanotechnological platforms, has represented the most effective and economically affordable approach to optimize the use of available antibiotics, improving their effectiveness profile. Abbreviations AZT: Aztreonam; BAT: Biofilm antibiotic tolerance; CF: Cystic Fibrosis; CIP: Ciprofloxacin; CRS: Chronic Rhinosinusitis; DPPG: 1,2-dipalmytoyl-sn-glycero-3-phosphoglycerol; DSPC: 1,2-distearoyl-sn-glycero-phosphocholine sodium salt; EPS: extracellular polymeric substance; FEV1: Forced Expiratory Volume in the first second; GSNO: S-nitroso-glutathione; LAE: lauroyl arginate ethyl; MIC: Minimum inhibitory Concentration; NCFB: Non-Cystic Fibrosis Bronchiectasis; NTM: Non-Tuberculous Mycobacteria; NTM-LD: Non-tuberculous mycobacteria Lung Disease PA: Pseudomonas aeruginosa; pDMAEMA: poly(dimethylaminoethyl methacrylate);pDMAEMA-co-PAA-co-BMA: poly(dimethylaminoethyl methacrylate)-co-propylacrylic acid-co-butyl methacrylate; PEG: polyethylene glycol; PEGDMA: polyethylene glycol dimethacrylate;PCL: Poly-ε-caprolactone; PLA: poly-lactic acid; PLGA: poly-lactic-co-glycolic acid; PVA: poli-vinyl alcohol; SA: Staphylococcus aureus; TIP: Tobramycin Inhalation Powder; TIS: Tobramycin Inhalation Solution; TPP: Tripolyphosphate.