Nanoparticles in the Treatment of Infections Caused by Multidrug-Resistant Organisms

Alternatives Therapeutic Approaches to Conventional Antibiotics: Advantages, Limitations and Potential Application in Medicine

Resistance to antimicrobials and particularly multidrug resistance is one of the greatest challenges in the health system nowadays. The continual increase in the rates of antimicrobial resistance worldwide boosted by the ongoing COVID-19 pandemic poses a major public health threat. Different approaches have been employed to minimize the effect of resistance and control this threat, but the question still lingers as to their safety and efficiency. In this context, new anti-infectious approaches against multidrug resistance are being examined. Use of new antibiotics and their combination with new β-lactamase inhibitors, phage therapy, antimicrobial peptides, nanoparticles, and antisense antimicrobial therapeutics are considered as one such promising approach for overcoming bacterial resistance. In this review, we provide insights into these emerging alternative therapies that are currently being evaluated and which may be developed in the future to break the progression of antimicrobial resistance. We focus on their advantages and limitations and potential application in medicine. We further highlight the importance of the combination therapy approach, wherein two or more therapies are used in combination in order to more effectively combat infectious disease and increasing access to quality healthcare. These advances could give an alternate solution to overcome antimicrobial drug resistance. We eventually hope to provide useful information for clinicians who are seeking solutions to the problems caused by antimicrobial resistance.

The Development of Technology to Prevent, Diagnose, and Manage Antimicrobial Resistance in Healthcare-Associated Infections

There is a growing risk of antimicrobial resistance (AMR) having an adverse effect on the healthcare system, which results in higher healthcare costs, failed treatments and a higher death rate. A quick diagnostic test that can spot infections resistant to antibiotics is essential for antimicrobial stewardship so physicians and other healthcare professionals can begin treatment as soon as possible. Since the development of antibiotics in the last two decades, traditional, standard antimicrobial treatments have failed to treat healthcare-associated infections (HAIs). These results have led to the development of a variety of cutting-edge alternative methods to combat multidrug-resistant pathogens in healthcare settings. Here, we provide an overview of AMR as well as the technologies being developed to prevent, diagnose, and control healthcare-associated infections (HAIs). As a result of better cleaning and hygiene practices, resistance to bacteria can be reduced, and new, quick, and accurate instruments for diagnosing HAIs must be developed. In addition, we need to explore new therapeutic approaches to combat diseases caused by resistant bacteria. In conclusion, current infection control technologies will be crucial to managing multidrug-resistant infections effectively. As a result of vaccination, antibiotic usage will decrease and new resistance mechanisms will not develop.

Antibiotic resistance and the alternatives to conventional antibiotics: The role of probiotics and microbiota in combating antimicrobial resistance

From the introduction of the first antibiotic to the present day, the emergence of antibiotic resistance has been a difficult problem for medicine. Regardless of the type of antibiotic resistance, the presence of resistant isolates in clinical and even asymptomatic fecal carriers becomes a difficult public health problem. Therefore, the use of new antimicrobial combination therapies or alternative agents with antimicrobial activity that have the least side effects, including plant-, metal-, and nanoparticle-based agents, could be crucial and useful. Recently, the use of probiotics as a hypothetical candidate to combat infectious disease control and antimicrobial resistance has received notable attention. Considering the alteration of the microbiota in fecal carriers and also in patients with resistant bacterial isolates, the use of probiotics could have an appropriate effect on the balance of the microbial population. In this review, we have attempted to discuss the history of antimicrobial resistance and provide an overview of microbiota change and the use of probiotics as new agents with antimicrobial activity associated with the emergence of resistant isolates.

Metal nanoparticles against multi-drug-resistance bacteria

Antimicrobial-resistant (AMR) bacterial infections remain a significant public health concern. The situation is exacerbated by the rapid development of bacterial resistance to currently available antimicrobials. Metal nanoparticles represent a new perspective in treating AMR due to their unique mechanisms, such as disrupting bacterial cell membrane potential and integrity, biofilm inhibition, reactive oxygen species (ROS) formation, enhancing host immune responses, and inhibiting RNA and protein synthesis by inducing intracellular processes. Metal nanoparticles (MNPs) properties such as size, shape, surface functionalization, surface charges, and co-encapsulated drug delivery capability all play a role in determining their potential against multidrug-resistant bacterial infections. Silver, gold, zinc oxide, selenium, copper, cobalt, and iron oxide nanoparticles have recently been studied extensively against multidrug-resistant bacterial infections. This review aims to provide insight into the size, shape, surface properties, and co-encapsulation of various MNPs in managing multidrug-resistant bacterial infections.

Antimicrobial effect of silver and gold nanoparticles in combination with linezolid on Enterococcus biofilm

Background and Objectives

In the past few years, application of new antimicrobial e.g. nanoparticles (NPs) to treat infection caused by drug-resistant bacteria has increased. This study aimed to determine antimicrobial property of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) in combination with linezolid on Enterococcus biofilm.

Materials and Methods

A total of forty-eight isolates of Enterococcus spp. were collected and confirmed by PCR method. The synthesis of biocompatible AgNPs was performed, then analyzed by Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy. We carried out minimum inhibitory concentration (MIC) and biofilm forming capacity of AgNPs and AuNPs with linezolid.

Results

Twenty-two E. faecium isolates and twentysix E. faecalis investigated in this study. Strong biofilm formation was seen in 12 (25%) of isolates, and others isolates (75%) formed moderate biofilm. AgNPs and Au-NPs size were 26 nm and 20 nm respectively. The MIC of AgNPs was 23.2 μg/ml, and AuNPs were 92.1 μg/ml and the lowest MIC was obtained 2 μg/ml in linezolid. Biofilm formation inhibitory activity by AuNPs + Linezolide and AgNPs + Linezolide 70 to 80 percent increased in average.

Conclusion

The antibiofilm activity of AgNPs and AuNPs increased when both agents were used in combination with linezolid in comparison with each agent alone.

Biomolecule conjugated inorganic nanoparticles for biomedical applications: A review

Last decade has witnessed impressive progress in the fields of medicine and bioengineering with the aid of nanomaterials. Nanomaterials are favoured for their improved bio-chemical as well as mechanical properties with tremendous applications in biomedical domains such as disease diagnosis, targeted drug delivery, medical imaging, in vitro diagnostics, designing innovatory cross-functional implants and regenerative tissue engineering. The current situation insists upon crafting nanotools that are capable of catering to biological needs and construct more efficient biomedical strategies. In the recent years, surface functionalization and capping with biomolecules has initiated substantial interest towards research. In this regard, search of suitable biofunctionalized nanoparticles seem to be like finding pearls from ocean. Conjugating biological molecules with inorganic materials has paved the way for unravelling innovative functional materials with dramatically improved properties and a wide range of uses. Inorganic nanoparticles such as metals, metal oxides, as well as quantum dots have been hybridised or conjugated with biomolecules such as proteins, peptides, carbohydrates, and nucleic acids. The present review reports on various biomolecule functionalized inorganic nanomaterials highlighting the biomolecule-inorganic nanoparticle interaction studies, the mechanism of functionalization, antimicrobial efficacy of the functionalised nanoconjugates and its use in various biomedical applications.

Emerging applications of nanotechnology in context to immunology: A comprehensive review

Numerous benefits of nanotechnology are available in many scientific domains. In this sense, nanoparticles serve as the fundamental foundation of nanotechnology. Recent developments in nanotechnology have demonstrated that nanoparticles have enormous promise for use in almost every field of life sciences. Nanoscience and nanotechnology use the distinctive characteristics of tiny nanoparticles (NPs) for various purposes in electronics, fabrics, cosmetics, biopharmaceutical industries, and medicines. The exclusive physical, chemical, and biological characteristics of nanoparticles prompt different immune responses in the body. Nanoparticles are believed to have strong potential for the development of advanced adjuvants, cytokines, vaccines, drugs, immunotherapies, and theranostic applications for the treatment of targeted bacterial, fungal, viral, and allergic diseases and removal of the tumor with minimal toxicity as compared to macro and microstructures. This review highlights the medical and non-medical applications with a detailed discussion on enhanced and targeted natural and acquired immunity against pathogens provoked by nanoparticles. The immunological aspects of the nanotechnology field are beyond the scope of this Review. However, we provide updated data that will explore novel theragnostic immunological applications of nanotechnology for better and immediate treatment.

Nanoparticles for Antimicrobial Agents Delivery-An Up-to-Date Review

Infectious diseases constitute an increasing threat to public health and medical systems worldwide. Particularly, the emergence of multidrug-resistant pathogens has left the pharmaceutical arsenal unarmed to fight against such severe microbial infections. Thus, the context has called for a paradigm shift in managing bacterial, fungal, viral, and parasitic infections, leading to the collision of medicine with nanotechnology. As a result, renewed research interest has been noted in utilizing various nanoparticles as drug delivery vehicles, aiming to overcome the limitations of current treatment options. In more detail, numerous studies have loaded natural and synthetic antimicrobial agents into different inorganic, lipid, and polymeric-based nanomaterials and tested them against clinically relevant pathogens. In this respect, this paper reviews the most recently reported successfully fabricated nanoformulations that demonstrated a great potential against bacteria, fungi, viruses, and parasites of interest for human medicine.

Advancements in antimicrobial nanoscale materials and self-assembling systems

Antimicrobial resistance is directly responsible for more deaths per year than either HIV/AIDS or malaria and is predicted to incur a cumulative societal financial burden of at least $100 trillion between 2014 and 2050. Already heralded as one of the greatest threats to human health, the onset of the coronavirus pandemic has accelerated the prevalence of antimicrobial resistant bacterial infections due to factors including increased global antibiotic/antimicrobial use. Thus an urgent need for novel therapeutics to combat what some have termed the 'silent pandemic' is evident. This review acts as a repository of research and an overview of the novel therapeutic strategies being developed to overcome antimicrobial resistance, with a focus on self-assembling systems and nanoscale materials. The fundamental mechanisms of action, as well as the key advantages and disadvantages of each system are discussed, and attention is drawn to key examples within each field. As a result, this review provides a guide to the further design and development of antimicrobial systems, and outlines the interdisciplinary techniques required to translate this fundamental research towards the clinic.

Design of Mesoporous Silica Nanoparticles for the Treatment of Amyotrophic Lateral Sclerosis (ALS) with a Therapeutic Cocktail Based on Leptin and Pioglitazone

Amyotrophic lateral sclerosis (ALS) is a devasting neurodegenerative disease with no cure to date. Therapeutic agents used to treat ALS are very limited, although combined therapies may offer a more effective treatment strategy. Herein, we have studied the potential of nanomedicine to prepare a single platform based on mesoporous silica nanoparticles (MSNs) for the treatment of an ALS animal model with a cocktail of agents such as leptin (neuroprotective) and pioglitazone (anti-inflammatory), which have already demonstrated promising therapeutic ability in other neurodegenerative diseases. Our goal is to study the potential of functionalized mesoporous materials as therapeutic agents against ALS using MSNs as nanocarriers for the proposed drug cocktail leptin/pioglitazone (MSN-LEP-PIO). The nanostructured materials have been characterized by different techniques, which confirmed the incorporation of both agents in the nanosystem. Subsequently, the effect, in vivo, of the proposed drug cocktail, MSN-LEP-PIO, was used in the murine model of TDP-43 proteinopathy (TDP-43^A315T mice). Body weight loss was studied, and using the rotarod test, motor performance was assessed, observing a continuous reduction in body weight and motor coordination in TDP-43^A315T mice and wild-type (WT) mice. Nevertheless, the disease progression was slower and showed significant improvements in motor performance, indicating that TDP-43^A315T mice treated with MSN-LEP-PIO seem to have less energy demand in the late stage of the symptoms of ALS. Collectively, these results seem to indicate the efficiency of the systems in vivo and the usefulness of their use in neurodegenerative models, including ALS.

Novel biosynthesis of tellurium nanoparticles and investigation of their activity against common pathogenic bacteria

Objectives

Tellurium has received substantial attention for its remarkable properties. This study performed in vitro and in vivo testing of the antibacterial action of tellurium nanoparticles biosynthesized in actinomycetes against methicillin-resistant Staphylococcus aureus (MRSA), a common blood bacterial pathogen.

Methods

Nine actinomycete isolates were tested for their potential to reduce potassium tellurite (K₂TeO₃) and form tellurium nanoparticles (TeNPs). The most efficient actinomycete isolate in producing Tellerium nanoparticles was identified through molecular protocols. The generated TeNPs were characterized using UV, TEM, EDX, XRD and FTIR. The bacterial species implicated in bloodstream infections were detected at El Hussein Hospital. Bacterial identification and antibiotic susceptibility testing were performed using Vitek 2. An animal infection model was used to test the efficacy of the produced TeNPs against the most commonly isolated methicillin-resistant S. aureus using survival assays, colony counting, cytokine assessment and biochemical testing.

Results

The most efficient actinomycete isolate was identified as Streptomyces graminisoli and given the accession number (OL773539). The mean particle size of the produced TeNPs was 21.4 nm, and rods and rosette forms were observed. Methicillin-resistant S. aureus (MRSA) was the main bacterium (60%) causing blood stream infections, and was followed by Escherichia coli (25%) and Klebsiella pneumoniae (15%). The produced TeNPs were tested against MRSA, the bacterium most frequently isolated from blood, and showed a promising action inhibition zone of 24 ± 0.7 mm and an MIC of 50 μg/ml. An animal infection model indicated the promise of TeNPs alone or in combination with standard drugs to combat MRSA in a rat intravenous infection model.

Conclusion

TeNPs combined with vancomycin have successive impact to combat bacteremia for further verification of results.

Magnetron Sputtering of Transition Metals as an Alternative Production Means for Antibacterial Surfaces

In the light of the SARS-CoV-2 pandemic and growing numbers of bacteria with resistance to antibiotics, the development of antimicrobial coatings is rising worldwide. Inorganic coatings are attractive because of low environmental leakage and wear resistance. Examples for coatings are hot metal dipping or physical vapor deposition of nanometer coatings. Here, magnetron sputtering of various transition metals, such as gold, ruthenium and tantalum, was investigated. Metal films were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy dispersive X-ray spectroscopy (EDX). We investigated the growth of Pseudomonas aeruginosa isolated from household appliances on different sputter-coated metal surfaces. The fine-grained nanometric structure of these metal coatings was between 14 nm (tantalum) and 26 nm (gold) and the roughness was in a range of 164 pm (ruthenium) to 246 pm (gold). Antibacterial efficacy of metal surfaces followed the order: gold > tantalum > ruthenium. Interestingly, gold had the strongest inhibitory effect on bacterial growth, as analyzed by LIVE/DEAD and CFU assay. High-magnification SEM images showed dead bacteria characterized by shrinkage induced by metal coatings. We conclude that sputtering might be a new application for the development of antimicrobial surfaces on household appliances and or surgical instruments.

Facile synthesis of starch and tellurium doped SrO nanocomposite for catalytic and antibacterial potential: In silico molecular docking studies

A chemical co-precipitation route was used to synthesize novel strontium oxide (SrO), SrO-starch composite and various tellurium (Te) concentrations were incorporated in SrO-starch composite. This study aims to enhance the catalytic activities and bactericidal behavior of SrO, SrO-starch composite with different percentage concentrations of Te doping and a fixed amount of starch nanoparticles. XRD affirmed that the dopant contribution was investigated to improve crystallinity. Surface morphological characteristics and elemental composition evaluation were determined using an FE-SEM and EDS exhibit a doping concentration of an element in the synthesized products. The configuration of Sr-O-Sr bonds and molecular vibrations has been indicated by FTIR spectra. In addition, dye degradation of prepared samples was investigated through catalytic activity (CA) in the existence of NaBH₄ act as a reduction representative. The Te-doped SrO-starch composite indicates superior catalytic activity and shows a degradation of Methylene blue dye (91.4 %) in an acidic medium. The synthesis nanocatalyst demonstrated impressive antibacterial activity against Staphylococcus aureus (S. aureus) at high and low concentrations exhibiting zones of inhibition 9.30 mm as compared to ciprofloxacin. Furthermore, molecular docking studies of synthesized nanocomposites were performed against selected enzyme targets, i.e., β-lactamase_E.coli and DNA Gyrase_E.coli.

Silver Nanoparticle-Based Therapy: Can It Be Useful to Combat Multi-Drug Resistant Bacteria?

The present review focuses on the potential use of silver nanoparticles in the therapy of diseases caused by antibiotic-resistant bacteria. Such bacteria are known as “superbugs”, and the most concerning species are Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus (methicillin and vancomycin-resistant), and some Enterobacteriaceae. According to the World Health Organization (WHO), there is an urgent need for new treatments against these “superbugs”. One of the possible approaches in the treatment of these species is the use of antibacterial nanoparticles. After a short overview of nanoparticle usage, mechanisms of action, and methods of synthesis of nanoparticles, emphasis has been placed on the use of silver nanoparticles (AgNPs) to combat the most relevant emerging resistant bacteria. The toxicological aspects of the AgNPs, both in vitro using cell cultures and in vivo have been reviewed. It was found that toxic activity of AgNPs is dependent on dose, size, shape, and electrical charge. The mechanism of action of AgNPs involves interactions at various levels such as plasma membrane, DNA replication, inactivation of protein/enzymes necessary, and formation of reactive oxygen species (ROS) leading to cell death. Researchers do not always agree in their conclusions on the topic and more work is needed in this field before AgNPs can be effectively applied in clinical therapy to combat multi-drug resistant bacteria.

Going Viral: Virus-Based Biological Control Agents for Plant Protection

The most economically important biotic stresses in crop production are caused by fungi, oomycetes, insects, viruses, and bacteria. Often chemical control is still the most commonly used method to manage them. However, the development of resistance in the different pathogens/pests, the putative damage on the natural ecosystem, the toxic residues in the field, and, thus, the contamination of the environment have stimulated the search for saferalternatives such as the use of biological control agents (BCAs). Among BCAs, viruses, a major driver for controlling host populations and evolution, are somewhat underused, mostly because of regulatory hurdles that make the cost of registration of such host-specific BCAs not affordable in comparison with the limited potential market. Here, we provide a comprehensive overview of the state of the art of virus-based BCAs against fungi, bacteria, viruses, and insects, with a specific focus on new approaches that rely on not only the direct biocidal virus component but also the complex ecological interactions between viruses and their hosts that do not necessarily result in direct damage to the host.

A Metal-Containing NP Approach to Treat Methicillin-Resistant Staphylococcus aureus (MRSA): Prospects and Challenges

Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of pneumonia in humans, and it is associated with high morbidity and mortality rates, especially in immunocompromised patients. Its high rate of multidrug resistance led to an exploration of novel antimicrobials. Metal nanoparticles have shown potent antibacterial activity, thus instigating their application in MRSA. This review summarizes current insights of Metal-Containing NPs in treating MRSA. This review also provides an in-depth appraisal of opportunities and challenges in utilizing metal-NPs to treat MRSA.

New formula of the green synthesised Au@Ag core@shell nanoparticles using propolis extract presented high antibacterial and anticancer activity

Antimicrobial alternatives such as nanoparticles are critically required to tackle bacterial infections, especially with the emerging threat of antibiotic resistance. Therefore, this study aimed to biosynthesize Au-Ag nanoparticles using propolis as a natural reducing agent and investigate their antibacterial activity against antibiotic-resistant Staphylococcus sciuri (S. sciuri), Pseudomonas aeruginosa (P. aeruginosa), and Salmonella enterica Typhimurium (S. enterica), besides demonstrating their anticancer activity in cancer cell lines. The biosynthesized Au@AgNPs were characterized using UV-Vis spectrophotometer, Transmission Electron Microscopy (TEM), Zeta potential, Dynamic Light Scattering (DLS), Fourier Transformation Infrared (FTIR), and Scanning Electron Microscopy (SEM). Moreover, the detection of antibacterial activity was assessed through disc diffusion, the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC), time-killing curve, and detection of cell membrane integrity via SEM. As a result, the UV-Vis spectrum revealed the formation of Au@AgNPs in a single peak between 533 and 555 nm. Furthermore, FTIR analysis confirmed nanoparticles' green synthesis due to the presence of carbon functional groups. The formulated Au@AgNPs showed antibacterial activity against both Gram-positive and Gram-negative bacteria. The MIC and the MBC of P. aeruginosa and S. sciuri were 31.25 µg/mL. However, nanoparticles were more effective on S. enterica with MIC of 7.5 µg/mL and MBC of 15.6 µg/mL. Furthermore, the time-killing curve of the three model bacteria with the treatment was effective at 50 µg/mL. Besides, SEM of the tested bacteria indicated unintegrated bacterial cell membranes and damage caused by Au@AgNPs. Regarding the anticancer activity, the results indicated that the biosynthesized Au@AgNPs have a cytotoxic effect on HEPG2 cell lines. In conclusion, this research revealed that the green synthesized Au@AgNPs could be effective antibacterial agents against S. sciuri, P. aeruginosa, and S. enterica and anticancer agents against HEPG2.

Antibacterial potency of cytocompatible chitosan-decorated biogenic silver nanoparticles and molecular insights towards cell-particle interaction

In the study, leaf extract of Carica papaya was utilized for the biogenic fabrication process of chitosan functionalized silver nanoparticles (Ag-Chito NPs). HRTEM analysis revealed that the fabricated Ag-Chito NPs was spherical in shape, with an average particle size of 13.31 (±0.07) nm. FTIR, UV-Vis, DLS, and other characterizations were also performed to analyze the diverse physicochemical properties of the particles. The antibacterial potency of the synthesized Ag-Chito NPs was tested against the two clinically isolated multidrug resistant uropathogenic bacterial strains, i.e. MLD 2 (Escherichia coli) and MLD 4 (Staphylococcus aureus) through MIC, MBC, time and concentration dependent killing kinetic assay, inhibition of biofilm formation assay, fluorescence and SEM imaging. Significantly, Ag-Chito NPs showed the highest sensitivity against the MLD 2 (MIC value of 12.5 μg/mL) strain, as compared to the MLD 4 (MIC value of 15 μg/mL) strain. From the hemolysis assay, it was revealed that Ag-Chito NPs exerted no significant toxicity up to 50 μg/mL against healthy human blood cells. Additionally, in silico analysis of chitosan (functionalized on the surface of AgNPs) and bacterial cell membrane protein also evidently suggested a strong interaction between Ag-Chito NPs and bacterial cells, which might be responsible for bacterial cell death.

Nanotheranostics and its role in diagnosis, treatment and prevention of COVID-19

Microbe-related, especially viral-related pandemics have currently paralyzed the world and such pathogenesis is expected to rise in the upcoming years. Although tremendous efforts are being made to develop antiviral drugs, very limited progress has been made in this direction. The nanotheranostic approach can be a highly potential rescue to combat this pandemic. Nanoparticles (NPs) due to their high specificity and biofunctionalization ability could be utilized efficiently for prophylaxis, diagnosis and treatment against microbial infections. In this context, titanium oxide, silver, gold NPs, etc. have already been utilized against deadly viruses like influenza, Ebola, HIV, and HBV. The discovery of sophisticated nanovaccines is under investigation and of prime importance to induce reproducible and strong immune responses against difficult pathogens. This review focuses on highlighting the role of various nano-domain materials such as metallic NPs, magnetic NPs, and quantum dots in the biomedical applications to combat the deadly microbial infections. Further, it also discusses the nanovaccines those are already available for various microbial diseases or are in clinical trials. Finally, it gives a perspective on the various nanotechnologies presently employed for efficient diagnosis and therapy against disease causing microbial infections, and how advancement in this field can benefit the health sector remarkably.

Metal nanoparticles and nanoparticle composites are effective against Haemophilus influenzae, Streptococcus pneumoniae, and multidrug-resistant bacteria

BACKGROUND

Treatment for lower respiratory tract infection caused by multidrug-resistant organisms (MDRO) are often limited. This study explored the activity of different metal nanoparticles against several respiratory pathogens including MDROs.

METHODS

Clinical isolates of carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Klebsiella pneumoniae (CRKP), Pseudomonas aeruginosa, Haemophilus influenzae, methicillin-resistant Staphylococcus aureus (MRSA), and Streptococcus pneumoniae were tested for in vitro susceptibilities to various antibiotics and nanoparticles. Minimum inhibitory concentrations (MICs) of silver-nanoparticle (Ag-NP), selenium-nanoparticle (Se-NP), and three composites solutions ND50, NK99, and TPNT1 (contained 5 ppm Ag-NP, 60 ppm ZnO-nanoparticle, and different concentrations of gold-nanoparticle or ClO₂) were determined by broth microdilution method.

RESULTS

Fifty isolates of each bacterial species listed above were tested. Ag-NP showed lower MICs to all species than Se-NP. The MIC₅₀s of Ag-NP for CRAB, CRKP, P. aeruginosa, and H. influenzae were <3.125 ppm, 25 ppm, <3.125 ppm, and <3.125 ppm, respectively, while those for S. pneumoniae and MRSA were >50 ppm and 50 ppm. Among CRAB, CRKP and P. aeruginosa, the MIC₅₀s of ND50, NK99, and TPNT1 for CRAB were the lowest (1/8 dilution, 1/8 dilution, and 1/8 dilution, respectively), and those for CRKP (>1/2 dilution, 1/2 dilution, and 1/2 dilution, respectively) were the highest. Both MRSA and S. pneumoniae showed high MIC₅₀s to ND50, NK99, and TPNT1.

CONCLUSIONS

Metal nanoparticles had good in vitro activity against Gram-negative bacteria. They might be suitable to be prepared as environmental disinfectants or inhaled agents to inhibit the growth of MDR Gram-negative colonizers in the lower respiratory tracts of patients with chronic lung diseases.

Antimicrobial Effects of Nanostructured Rare-Earth-Based Orthovanadates

The search for novel antimicrobial agents is of huge importance. Nanomaterials can come to the rescue in this case. The aim of this study was to assess the cytotoxicity and antimicrobial effects of rare-earth-based orthovanadate nanoparticles. The cytotoxicity against host cells and antimicrobial activity of LaVO₄:Eu³⁺ and GdVO₄:Eu³⁺ nanoparticles were analyzed. Effects of nanomaterials on fibroblasts were assessed by MTT, neutral red uptake and scratch assays. The antimicrobial effects were evaluated by the micro-dilution method estimating the minimum inhibitory concentration (MIC) of nanoparticles against various strains of microorganisms, DNA cleavage and biofilm inhibition. GdVO₄:Eu³⁺ nanoparticles were found to be less toxic against eukaryotic cells compared with LaVO₄:Eu³⁺. Both nanoparticles exhibited antimicrobial activity and the highest MIC values were 64 mg/L for E. hirae, E. faecalis and S. aureus shown by GdVO₄:Eu³⁺ nanoparticles. Nanoparticles demonstrated good DNA cleavage activity and induction of double-strand breaks in supercoiled plasmid DNA even at the lowest concentrations used. Both nanoparticles showed the biofilm inhibition activity against S. aureus at 500 mg/L and reduced the microbial cell viability. Taken the results of host toxicity and antimicrobial activity studies, it can be assumed that GdVO₄:Eu³⁺ nanoparticles are more promising antibacterial agents compared with LaVO₄:Eu³⁺ nanoparticles.

Comparative Account of Biogenic Synthesis of Silver Nanoparticles Using Probiotics and Their Antimicrobial Activity Against Challenging Pathogens

The present work focusses on development of a safe, inexpensive, and more accessible source for biosynthesis of silver nanoparticles. Four different in-house probiotic isolates, i.e., Lactobacillus pentosus S6, Lactobacillus plantarum F22, Lactobacillus crustorum F11, and Lactobacillus paraplantarum KM1 isolated from different food sources, were used in the current study to check their ability to synthesize silver nanoparticles. All the probiotic-synthesized silver nanoparticles show maximum surface plasmon resonance (SPR) at a peak of 450 nm, which confirms the formation of silver nanoparticles. Scanning electron microscopy (SEM) analysis identified the shape and distribution of silver nanoparticles. Transmission electron microscopy (TEM) revealed the average size of synthesized nanoparticles in the range of 10–50 nm, with the smallest size of 5 nm for silver nanoparticles synthesized by L. crustorum F11. Further, Fourier-transform infrared spectroscopy (FTIR) detected the presence of different functional groups responsible for reduction of silver ion to form silver nanoparticles. The antimicrobial activity of these AgNPs was also found to be effective against different bacterial and fungal pathogens, viz., antibiotic-resistant Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Pythium aphanidermatum, Fusarium oxysporum, and Phytopthora parasitica. However, L. crustorum F11–synthesized AgNP showed maximum inhibition against all the bacterial and fungal pathogens, with highest against S. aureus (20 ± 0.61 mm) and F. oxysporum (23 ± 0.37). Findings from this study provide a durable and eco-friendly method for the biosynthesis of silver nanoparticles, having strong antimicrobial activity against different multidrug-resistant microorganisms.

Graphical abstract

Rapid Assessment of Biological Activity of Ag-Based Antiviral Coatings for the Treatment of Textile Fabrics Used in Protective Equipment Against Coronavirus

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its variants have rapidly spread worldwide, causing coronavirus disease (COVID-19) with numerous infected cases and millions of deaths. Therefore, developing approaches to fight against COVID-19 is currently the most priority goal of the scientific community. As a sustainable solution to stop the spread of the virus, a green dip-coating method is utilized in the current work to prepare antiviral Ag-based coatings to treat cotton and synthetic fabrics, which are the base materials used in personal protective equipment such as gloves and gowns. Characterization results indicate the successful deposition of silver (Ag) and stabilizers on the cotton and polypropylene fiber surface, forming Ag coatings. The deposition of Ag and stabilizers on cotton and etched polypropylene (EPP) fabrics is dissimilar due to fiber surface behavior. The obtained results of biological tests reveal the excellent antibacterial property of treated fabrics with large zones of bacterial inhibition. Importantly, these treated fabrics exhibit an exceptional antiviral activity toward human coronavirus OC43 (hCoV-OC43), whose infection could be eliminated up to 99.8% when it was brought in contact with these fabrics after only a few tens of minutes. Moreover, the biological activity of treated fabrics is well maintained after a long period of up to 40 days of post-treatment.

Curcumin assisted green synthesis of silver and zinc oxide nanostructures and their antibacterial activity against some clinical pathogenic multi-drug resistant bacteria

According to WHO warnings, the antibiotic resistance crisis is a severe health issue in the 21st century, attributed to the overuse and misuse of these medications. Consequently, the dramatic spreading rate of the drug-resistant microbial pathogens strains. The microbiological, biochemical tests and antibiotic sensitivity identified the bacteria's multi-drug resistance (MDR). About 150 different clinical samples were taken from hospitalized patients, both males, and females, ranging from 9 to 68 years. Gram-negative strains were (70.0%), while Gram-positive isolates were (30.0%). Among sixteen antibiotics, antibiotic susceptibility of imipenem was found to be the most efficient drug against most of the Gram-negative and Gram-positive isolates, followed by meropenem, depending on the culture and sensitivity results. All the experimental bacteria showed multidrug-resistant phenomena. In this study, green synthesized silver (Cur-Ag NPs) and zinc oxide (Cur-ZnO NPs) nanoparticles in the presence of curcumin extract. In addition, their physicochemical properties have been characterized using different techniques such as UV-Vis spectroscopy, transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and colloidal properties techniques. Furthermore, curcumin-capped silver nanoparticles (AgNPs) exhibited solid antimicrobial action against the experimental bacterial isolates, except Proteus vulgaris (i.e., P. vulgaris). Curcumin-capped zinc oxide nanoparticles (ZnO NPs) found antimicrobial activity against all tested strains. Finally, the minimum inhibitory concentration exhibited values from 3.9 to 15.6 μg ml-1, which is too small compared to other traditional antibiotics. In addition, the green-synthesized Cur-Ag NPs and Cur-ZnO NPs showed good biocompatibility.

Synergism between metallic nanoparticles and antibiotics

The discovery of antibiotics in the twentieth century made it possible to treat bacterial infections and revolutionized modern medicine. However, gradually, it is possible to perceive a decrease in the effectiveness of antimicrobial agents against pathogenic isolates, which, together with the low investment in the discovery and/or development of new antibiotics by large pharmaceutical companies since the 1960s, makes it increasingly difficult to treatment of infections caused by these microorganisms. The search for strategies capable of potentiating the effect of existing drugs through the development of new therapeutic approaches, which also have the potential to circumvent bacterial resistance to antibiotics, has become indispensable. In this context, metallic nanoparticles stand out, as they could be used to act synergistically with drugs. Thus, the objective of this review was to present the latest information on the synergistic activity of antibiotics with metallic nanoparticles, pointing out this association as a promising alternative for the preservation of bacterial sensitivity to these drugs. The different metallic nanoparticles can present different benefits in the treatment of bacterial infections, with this being able to potentiate the bacterial activity of antibiotics that are widely used in the clinic, being able to increase the susceptibility in multiresistant microorganisms. KEY POINTS: • Metallic nanoparticles increased the antimicrobial action of drugs; • Metallic nanoparticles compromise the action of bacterial efflux pumps; • Biofilm formation was inhibited after treatment with metallic nanoparticles.

Synthesis, Characterization and Antimicrobial Activity of Zinc Oxide Nanoparticles against Selected Waterborne Bacterial and Yeast Pathogens

The disinfection of wastewater using nanoparticles (NPs) has become a focal area of research in water treatment. In this study, zinc oxide (ZnO) NPs were synthesized using the microwave heating crystallization technique and characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Qualitative well diffusion and quantitative minimum inhibitory concentration (MIC) tests were conducted to determine the antimicrobial activity of ZnO NPs against selected waterborne pathogenic microbes. FTIR spectral studies confirmed that the binding of urea with Zn occurs through Zn–O stretching. XRD confirmed the crystallized identity in a hexagonal ZnO wurtzite-type structure. The formation of zones of inhibition and low MIC values in the antimicrobial analysis were indicative of the effective antimicrobial activity of zinc oxide nanoparticles against the test microorganisms. The application of metallic nanoparticles in water treatment could curb the spread of waterborne microbial diseases.

Comparative Analysis of the Mechanism of Resistance to Silver Nanoparticles and the Biocide 2,2-Dibromo-3-Nitrilopropionamide

Antimicrobials such as nanoparticles and biocides are used to control microbial growth. We used Escherichia coli to study the process of acquired resistance to silver nanoparticles (Ag-NP) and the industrial biocide DBNPA when grown in sub-MICs. We determined the MICs of these two antimicrobials against E. coli. We then performed an experimental evolution study where E. coli was grown in subinhibitory concentrations of the antimicrobials and transferred 10 times. We then tracked the changes in growth characteristics, lactate dehydrogenase (LDH) activity, reactive oxidative species (ROS) production, and the role of efflux pumps in conferring resistance. We also performed genome sequencing to determine the genetic basis for acquired resistance. Our results showed that E. coli could rapidly develop resistance to Ag-NP and DBNPA after growth in low concentrations of the antimicrobials. The expression of efflux pumps plays a vital role in both Ag-NP and DBNPA resistance. Multiple mutations occurred in the adapted strains that may confer resistance to both Ag-NP and DBNPA. Our study provides insights into mechanisms of adaptation and resistance to antimicrobials. Our results suggest that there are some shared mechanisms to resist nanoparticles and biocides as well as some key differences. The mechanism of resistance to Ag-NP might be related to flagellin production, while efflux pumps seem to be associated with resistance to DBNPA. This work provides a comparative study of the mechanisms of acquired resistance to these two types of antimicrobials.

Hesperidin-, Curcumin-, and Amphotericin B- Based Nano-Formulations as Potential Antibacterials

To combat the public health threat posed by multiple-drug-resistant (MDR) pathogens, new drugs with novel chemistry and modes of action are needed. In this study, several drugs including Hesperidin (HES), curcumin (CUR), and Amphotericin B (AmpB) drug-nanoparticle formulations were tested for antibacterial strength against MDR Gram-positive bacteria, including Bacillus cereus, Streptococcus pyogenes, Methicillin-resistant Staphylococcus aureus (MRSA), and Streptococcus pneumoniae, and Gram-negative bacteria, including Escherichia coli K1, Pseudomonas aeruginosa, Salmonella enterica, and Serratia marcescens. Nanoparticles were synthesized and subjected to Atomic force microscopy, Fourier transform-infrared spectroscopy, and Zetasizer for their detailed characterization. Antibacterial assays were performed to determine their bactericidal efficacy. Lactate dehydrogenase (LDH) assays were carried out to measure drugs' and drug-nanoparticles' cytotoxic effects on human cells. Spherical NPs ranging from 153 to 300 nm were successfully synthesized. Results from antibacterial assays revealed that drugs and drug-nanoparticle formulations exerted bactericidal activity against MDR bacteria. Hesperidin alone failed to exhibit antibacterial effects but, upon conjugation with cinnamic-acid-based magnetic nanoparticle, exerted significant bactericidal activity against both the Gram-positive and Gram-negative isolates. AmpB-LBA-MNPs produced consistent, potent antibacterial efficacy (100% kill) against all Gram-positive bacteria. AmpB-LBA-MNPs showed strong antibacterial activity against Gram-negative bacteria. Intriguingly, all the drugs and their conjugated counterpart except AmpB showed minimal cytotoxicity against human cells. In summary, these innovative nanoparticle formulations have the potential to be utilized as therapeutic agents against infections caused by MDR bacteria and represent a significant advancement in our effort to counter MDR bacterial infections.

Facet-Dependent Bactericidal Activity of Ag3PO4 Nanostructures against Gram-Positive/Negative Bacteria

Ag₃PO₄ nanostructures (APNs) containing silver (Ag metal; of the noble metal families) have the potential to exhibit enzyme-mimetic activity. A nanostructure shape, including its surface facets, can improve the bioactivity of enzyme mimicry, yet the molecular mechanisms remain unclear. Herein, we report facet-dependent peroxidase and oxidase-like activity of APNs with both antibacterial and biofilm degrading properties through the generation of reactive oxygen species. Cubic APNs had superior antibacterial effects than rhombic dodecahedral shapes when inhibiting Gram-positive and Gram-negative bacterial pathogen proliferation and biofilm degradation. A similar performance was observed for rhombic dodecahedral shapes, being greater than tetrahedral-shaped APNs. The extent of enzyme-mimetic activity is attributed to the facets {100} present in cubic APNs that led the peroxide radicals to inhibit the proliferation of bacteria and degrade biofilm. These facets were compared to rhombic dodecahedral APNs {110} and tetrahedral APNs {111}, respectively, to reveal a facet-dependent enhanced antibacterial activity, providing a plausible mechanism for shape-dependent APNs material enzyme-mimetic effects on bacteria. Thus, our research findings can provide a direction to optimize bactericidal materials using APNs in clinically relevant applications.

Antibiotic resistant bacteria: current situation and treatment options to accelerate the development of a new antimicrobial arsenal

INTRODUCTION

Antibiotic resistance is one of the biggest public health threats worldwide. Currently, antibiotic-resistant bacteria kill 700,000 people every year. These data represent the near future in which we find ourselves, a "post-antibiotic era" where the identification and development of new treatments are key. This review is focused on the current and emerging antimicrobial therapies which can solve this global threat.

AREAS COVERED

Through a literature search using databases such as Medline and Web of Science, and search engines such as Google Scholar, different antimicrobial therapies were analyzed, including pathogen-oriented therapy, phagotherapy, microbiota and antivirulent therapy. Additionally, the development pathways of new antibiotics were described, emphasizing on the potential advantages that the combination of a drug repurposing strategy with the application of mathematical prediction models could bring to solve the problem of AMRs.

EXPERT OPINION

This review offers several starting points to solve a single problem: reducing the number of AMR. The data suggest that the strategies described could provide many benefits to improve antimicrobial treatments. However, the development of new antimicrobials remains necessary. Drug repurposing, with the application of mathematical prediction models, is considered to be of interest due to its rapid and effective potential to increase the current therapeutic arsenal.

Safer plant-based nanoparticles for combating antibiotic resistance in bacteria: A comprehensive review on its potential applications, recent advances, and future perspective

BACKGROUND

Antibiotic resistance is one of the current threats to human health, forcing the use of drugs that are more noxious, costlier, and with low efficiency. There are several causes behind antibiotic resistance, including over-prescription of antibiotics in both humans and livestock. In this scenario, researchers are shifting to new alternatives to fight back this concerning situation.

SCOPE AND APPROACH

Nanoparticles have emerged as new tools that can be used to combat deadly bacterial infections directly or indirectly to overcome antibiotic resistance. Although nanoparticles are being used in the pharmaceutical industry, there is a constant concern about their toxicity toward human health because of the involvement of well-known toxic chemicals (i.e., sodium/potassium borohydride) making their use very risky for eukaryotic cells.

KEY FINDINGS AND CONCLUSIONS

Multiple nanoparticle-based approaches to counter bacterial infections, providing crucial insight into the design of elements that play critical roles in the creation of antimicrobial nanotherapeutic drugs, are currently underway. In this context, plant-based nanoparticles will be less toxic than many other forms, which constitute promising candidates to avoid widespread damage to the microbiome associated with current practices. This article aims to review the actual knowledge on plant-based nanoparticle products for antibiotic resistance and the possible replacement of antibiotics to treat multidrug-resistant bacterial infections.

Microbial Resistance to Antibiotics and Effective Antibiotherapy

Currently, the efficacy of antibiotics is severely affected by the emergence of the antimicrobial resistance phenomenon, leading to increased morbidity and mortality worldwide. Multidrug-resistant pathogens are found not only in hospital settings, but also in the community, and are considered one of the biggest public health concerns. The main mechanisms by which bacteria develop resistance to antibiotics include changes in the drug target, prevention of entering the cell, elimination through efflux pumps or inactivation of drugs. A better understanding and prediction of resistance patterns of a pathogen will lead to a better selection of active antibiotics for the treatment of multidrug-resistant infections.

Experimental Confirmation of Antimicrobial Effects of GdYVO4:Eu3+ Nanoparticles

Nanotechnology can be applied to design antibacterial agents to combat antibiotic resistance. The aim of the present study was to assess the antimicrobial effects and cytotoxicity of GdYVO₄:Eu³⁺ nanoparticles (NPs). Biofilm inhibition activity, antimicrobial activity, bacterial viability inhibition and DNA cleavage activity of GdYVO₄:Eu³⁺ NPs were studied. In addition, the impact of GdYVO₄:Eu³⁺ NPs on the mitochondrial membrane potential (ΔΨ_M) of host immune cells and, hence, their apoptosis was analyzed by JC-1 staining using flow cytometry. GdYVO₄:Eu³⁺ NPs demonstrated good antimicrobial, cell viability inhibition and DNA cleavage activities. In addition, GdYVO₄:Eu³⁺ NPs showed good biofilm inhibition activity against S. aureus and P. aeruginosa and inhibition percentages were 89.15% and 79.54%, respectively. However, GdYVO₄:Eu³⁺ NPs promoted mitochondrial depolarization and apoptosis of leukocytes at high concentrations. GdYVO₄:Eu³⁺ nanoparticles are promising antibacterial agents. However, more efforts should be exerted to ensure their safety.

Antibacterial and Biofilm-Eradicating Activities of pH-Responsive Vesicles against Pseudomonas aeruginosa

The formation of biofilms by a microcolony of bacteria is a significant burden on the healthcare industry due to difficulty eradicating it. In this study, pH-responsive vesicles capable of releasing apramycin (APR), a model aminoglycoside antibiotic, in response to the low pH typical of establishedPseudomonas aeruginosa biofilms resulted in improved eradication of existing biofilms in comparison to the free drug. The amphiphilic polymeric vesicle (PV) comprised of block polymer poly (ethylene glycol)-block-poly 2-(dimethylamino) ethyl methacrylate (mPEG-b-pDEAEMA) averaged 128 nm. The drug encapsulation content of APR in PV/APR was confirmed to be 28.2%, and the drug encapsulation efficiency was confirmed to be 51.2%. At pH 5.5, PV/APR released >90% APR after 24 h compared to <20% at pH 7.4. At pH 5.5, protonation of the pDEAEMA block results in a zeta potential of +23 mV compared to a neutral zeta potential of +2.2 mV at pH 7.4. Confocal microscopy, flow cytometry, and scanning electron microscopy reveal that the positively charged vesicles can compromise the integrity of the planktonic bacterial membrane in a pH-dependent manner. In addition, PV/APR is able to diffuse into mature biofilms to release APR in the acidic milieu of biofilm bacteria, and PV/APR was more efficient at eliminating preexisting biofilms compared to free APR at 128 and 256 μg/mL. This study reveals that dynamic charge density in response to pH can lead to differential levels of interactions with the biofilm and bacterial membrane. This effectively results in enhanced antibacterial and antibiofilm properties against both planktonic and difficult-to-treat biofilm bacteria at concentrations significantly lower than those of the free drug. Overall, this pH-responsive vesicle could be especially promising for treating biofilm-associated infectious diseases.

Exploring the applications of hyaluronic acid-based nanoparticles for diagnosis and treatment of bacterial infections

Hyaluronic acid (HA) has become a topic of significant interest in drug delivery research due to its excellent properties, including biosafety, biodegradability, and nonimmunogenicity. Moreover, due to its ease of modification, HA can be used to prepare several HA‐based nanosystems using various approaches. These approaches involve conjugating/grafting of hydrophobic moieties, polyelectrolytes complexation with cationic polymers, or surface modification of various nanoparticles using HA. These nanoparticles are able to selectively deliver antibacterial drugs or diagnostic molecules into the site of infections. In addition, HA can bind with overexpressed cluster of differentiation 44 (CD44) receptors in macrophages and also can be degraded by a family of enzymes called hyaluronidase (HAase) to release drugs or molecules. By binding with these receptors or being degraded at the infection site by HAase, HA‐based nanoparticles allow enhanced and targeted antibacterial delivery. Herein, we present a comprehensive and up‐to‐date review that highlights various techniques of preparation of HA‐based nanoparticles that have been reported in the literature. Furthermore, we also discuss and critically analyze numerous types of HA‐based nanoparticles that have been employed in antibacterial delivery to date. This article offers a critical overview of the potential of HA‐based nanoparticles to overcome the challenges of conventional antibiotics in the treatment of bacterial infections. Moreover, this review identifies further avenues of research for developing multifunctional and biomimetic HA‐based nanoparticles for the treatment, prevention, and/or detection of pathogenic bacteria.

This article is categorized under:

Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease

Nanotechnology Approaches to Biology > Nanoscale Systems in Biology

Therapeutic Approaches and Drug Discovery > Emerging Technologies

Effect of Nanosulfur Against Multidrug-Resistant Staphylococcus pseudintermedius and Pseudomonas aeruginosa

Multidrug resistance (MDR) has significantly increased in the past decades and the use of nanotechnology has opened new venues for novel treatments. Nanosulfur is a potent antimicrobial agent and a cheaper alternative to other nanomaterials. However, very few studies have been published on its activity against MDR organisms. Therefore, the goal of this in vitro study was to assess cytotoxicity, antimicrobial, and anti-biofilm activity of nanosulfur (47 nm, orthorhombic) against clinical isolates of MDR Staphylococcus pseudintermedius (SP) and Pseudomonas aeruginosa (PA) in planktonic and biofilm state using canine skin explants. Nanosilver (50 nm, spherical) was tested as a comparative control. Concentrations between 1866.7 and 0.11 μg/mL of both nanoparticles were tested. The ultrastructure of nanosulfur was assessed via electron microscopy. Both types of nanoparticles showed no direct cytotoxicity on a canine keratinocyte cell line. In the planktonic phase, nanosulfur was able to inhibit or kill (6-log₁₀ reduction of CFU) 7 of 10 MDR-SP isolates at 233.3 μg/mL, whereas, when in biofilm state, 6 of 10 isolates were killed at different concentrations (233.33 to 1866.7 μg/mL). Nanosilver did not show any antimicrobial or anti-biofilm activity at any concentrations tested. Both types of nanoparticles were ineffective against MDR-PA in either state. Ultrastructurally, nanosulfur was present in individual nanoparticles as well as forming larger nanoclusters. This is the first study showing an antimicrobial and anti-biofilm activity of nanosulfur for MDR-SP in absence of cytotoxicity. Nanosulfur has the potential to be used in veterinary and human medicine as effective, safe, and cheap alternative to antimicrobials and anti-biofilm agents currently available. KEY POINTS: • Nanosulfur is a better alternative than nanosilver to treat MDR-Staphylococci. • Nanosulfur is an effective agent against MDR-Staphyloccocal biofilm. • Canine skin explant model is reliable for testing anti-biofilm agents.

Progress Report: Antimicrobial Drug Discovery in the Resistance Era

Antibiotic resistance continues to be a most serious threat to public health. This situation demands that the scientific community increase their efforts for the discovery of alternative strategies to circumvent the problems associated with conventional small molecule therapeutics. The Global Antimicrobial Resistance and Use Surveillance System (GLASS) Report (published in June 2021) discloses the rapidly increasing number of bacterial infections that are mainly caused by antimicrobial-resistant bacteria. These concerns have initiated various government agencies and other organizations to educate the public regarding the appropriate use of antibiotics. This review discusses a brief highlight on the timeline of antimicrobial drug discovery with a special emphasis on the historical development of antimicrobial resistance. In addition, new antimicrobial targets and approaches, recent developments in drug screening, design, and delivery were covered. This review also discusses the emergence and roles of various antibiotic adjuvants and combination therapies while shedding light on current challenges and future perspectives. Overall, the emergence of resistant microbial strains has challenged drug discovery but their efforts to develop alternative technologies such as nanomaterials seem to be promising for the future.

Overcoming Multidrug Resistance of Antibiotics via Nanodelivery Systems

Antibiotic resistance has become a threat to microbial therapies nowadays. The conventional approaches possess several limitations to combat microbial infections. Therefore, to overcome such complications, novel drug delivery systems have gained pharmaceutical scientists’ interest. Significant findings have validated the effectiveness of novel drug delivery systems such as polymeric nanoparticles, liposomes, metallic nanoparticles, dendrimers, and lipid-based nanoparticles against severe microbial infections and combating antimicrobial resistance. This review article comprises the specific mechanism of antibiotic resistance development in bacteria. In addition, the manuscript incorporated the advanced nanotechnological approaches with their mechanisms, including interaction with the bacterial cell wall, inhibition of biofilm formations, activation of innate and adaptive host immune response, generation of reactive oxygen species, and induction of intracellular effect to fight against antibiotic resistance. A section of this article demonstrated the findings related to the development of delivery systems. Lastly, the role of microfluidics in fighting antimicrobial resistance has been discussed. Overall, this review article is an amalgamation of various strategies to study the role of novel approaches and their mechanism to fight against the resistance developed to the antimicrobial therapies.

Nanomaterials Aiming to Tackle Antibiotic-Resistant Bacteria

The global health of humans is seriously affected by the dramatic increases in the resistance patterns of antimicrobials against virulent bacteria. From the statements released by the Centers for Disease Control and Prevention about the world entering a post-antibiotic era, and forecasts about human mortality due to bacterial infection being increased compared to cancer, the current body of literature indicates that emerging tools such as nanoparticles can be used against lethal infections caused by bacteria. Furthermore, a different concept of nanomaterial-based methods can cope with the hindrance faced by common antimicrobials, such as resistance to antibiotics. The current review focuses on different approaches to inhibiting bacterial infection using nanoparticles and aiding in the fabrication of antimicrobial nanotherapeutics by emphasizing the functionality of nanomaterial surface design and fabrication for antimicrobial cargo.

Role of nanomaterials in deactivating multiple drug resistance efflux pumps - A review

The changes in lifestyle and living conditions have affected not only humans but also microorganisms. As man invents new drugs and therapies, pathogens alter themselves to survive and thrive. Multiple drug resistance (MDR) is the talk of the town for decades now. Many generations of medications have been termed useless as MDR rises among the infectious population. The surge in nanotechnology has brought a new hope in reducing this aspect of resistance in pathogens. It has been observed in several laboratory-based studies that the use of nanoparticles had a synergistic effect on the antibiotic being administered to the pathogen; several resistant strains scummed to the stress created by the nanoparticles and became susceptible to the drug. The major cause of resistance to date is the efflux system, which makes the latest generation of antibiotics ineffective without reaching the target site. If species-specific nanomaterials are used to control the activity of efflux pumps, it could revolutionize the field of medicine and make the previous generation resistant medications active once again. Therefore, the current study was devised to assess and review nanoparticles' role on efflux systems and discuss how specialized particles can be designed towards an infectious host's particular drug ejection systems.

Light Triggered Enhancement of Antibiotic Efficacy in Biofilm Elimination Mediated by Gold-Silver Alloy Nanoparticles

Bacterial biofilm is a tri-dimensional complex community of cells at different metabolic stages involved in a matrix of self-produced extracellular polymeric substances. Biofilm formation is part of a defense mechanism that allows the bacteria to survive in hostile environments, such as increasing resistance or tolerance to antimicrobial agents, causing persistent infections hard to treat and impair disease eradication. One such example is bovine mastitis associated with Streptococcus dysgalactiae subsp. dysgalactiae (SDSD), whose worldwide health and economic impact is on the surge. As such, non-conventional nanobased approaches have been proposed as an alternative to tackle biofilm formation and to which pathogenic bacteria fail to adapt. Among these, metallic nanoparticles have gained significant attention, particularly gold and silver nanoparticles, due to their ease of synthesis and impact against microorganism growth. This study provides a proof-of-concept investigation into the use of gold-silver alloy nanoparticles (AuAgNPs) toward eradication of bacterial biofilms. Upon visible light irradiation of AuAgNPs there was considerable disturbance of the biofilms' matrix. The hindering of structural integrity of the biofilm matrix resulted in an increased permeability for entry of antibiotics, which then cause the eradication of biofilm and inhibit subsequent biofilm formation. Additionally, our results that AuAgNPs inhibited the formation of SDSD biofilms via distinct stress pathways that lead to the downregulation of two genes critical for biofilm production, namely, brpA-like encoding biofilm regulatory protein and fbpA fibronectin-binding protein A. This study provides useful information to assist the development of nanoparticle-based strategies for the active treatment of biofilm-related infections triggered by photoirradiation in the visible.