Novel antibiotic-loaded particles conferring eradication of deep tissue bacterial reservoirs for the treatment of chronic urinary tract infection

A low-molecular-weight α-glucan from edible fungus Agaricus blazei Murrill activates macrophage TFEB-mediated antibacterial defense to combat implant-associated infection

Implant-associated infection (IAI) is a prevalent and potentially fatal complication of orthopaedic surgery. Boosting antibacterial immunity, particularly the macrophage-mediated response, presents a promising therapeutic approach for managing persistent infections. In this study, we successfully isolated and purified a homogeneous and neutral water-soluble polysaccharide, designated as AM-1, from the edible fungus Agaricus blazei Murrill. Structure analysis revealed that AM-1 (Mw = 3.87 kDa) was a low-molecular-weight glucan characterized by a primary chain of →4)-α-D-Glcp-(1 → and side chains that were linked at the O-6 and O-3 positions. In vivo assays showed that AM-1 effectively attenuated the progression of infection and mitigated infectious bone destruction in IAI mouse models. Mechanistically, AM-1 promotes intracellular autophagy-lysosomal biogenesis by inducing the nuclear translocation of transcription factor EB, finally enhancing the bactericidal capabilities and immune-modulatory functions of macrophages. These findings demonstrate that AM-1 significantly alleviates the progression of challenging IAIs as a presurgical immunoenhancer. Our research introduces a novel therapeutic strategy that employs natural polysaccharides to combat refractory infections.

Relationship between urinary tract infections and serum vitamin D level in adults and children- a literature review

Over time, researchers have accumulated significant evidence indicating that vitamin D deficiency not only impacts skeletal health but also contributes to the development and progression of various diseases, including cancer, diabetes, and cardiovascular conditions. The risk of low serum 1, 25(OH)2D3 level ultimately directs the way to morbidity, the beginning of new diseases, and numerous infections. Infections are the first entity that affects those with vitamin D deficiency. The common infection is urinary tract infection (UTI), and its relationship with vitamin D deficiency or insufficiency remains controversial. This infection affects both men and women, but comparatively, women are more prone to this infection because of the short length of the urethra, which makes an easy entry for the bacteria. The low level of serum vitamin D increases the risk of UTIs in children. Recurrent UTIs are one of the major weaknesses in women; if left untreated, they progress to appallingly serious conditions like kidney dysfunction, liver damage, etc. Hence improving the vitamin D status may help to improve the immune system, thus making it more resistant to infections. In this review, we have focused on examining whether vitamin D deficiency and insufficiency are the causes of UTIs and the association between them in women and children. We have also described the connection between vitamin D deficiency and insufficiency with UTIs and additional nanotechnology- based treatment strategies.

Antibiotic-loaded nanoparticles for the treatment of intracellular methicillin-resistant Staphylococcus Aureus infections: In vitro and in vivo efficacy of a novel antibiotic

Antimicrobial resistance is considered one of the biggest threats to public health worldwide. Methicillin-resistant S. aureus is the causative agent of a number of infections and lung colonization in people suffering from cystic fibrosis. Moreover, a growing body of evidence links the microbiome to the development of cancer, as well as to the success of the treatment. In this view, the development of novel antibiotics is of critical importance, and SV7, a novel antibiotic active against MRSA at low concentrations, represents a promising candidate. However, the low aqueous solubility of SV7 hampers its therapeutic translation. In this study, SV7 was encapsulated in poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) to improve the solubility profile, to ensure sustained release and eventually support deposition in the airways. Furthermore, PLGA NPs were formulated as dry powder to extend their shelf-life and were shown to efficiently target intracellular infections. After identifying a formulation with suitable physico-chemical characteristics, SV7-loaded NPs were investigated in vitro in terms of inhibitory activity against MRSA, and their safety profile in lung epithelial cells. Subsequently, the activity against MRSA intracellular infections was investigated in a co-culture model of MRSA and macrophages. To test the translatability of our findings, SV7-loaded NPs were tested in vivo in a Galleria mellonella infection model. In conclusion, SV7-loaded NPs showed a safe profile and efficient inhibitory activity against MRSA at low concentrations. Furthermore, their activity against intracellular infections was confirmed, and was retained in vivo, rendering them a promising candidate for treatment of MRSA lung infections.

Mitigating infections in implantable urological continence devices: risks, challenges, solutions, and future innovations. A comprehensive literature review

PURPOSE OF REVIEW

Stress urinary incontinence is a growing issue in ageing men, often following treatment for prostate cancer or bladder outflow obstruction. While implantable urological devices offer relief, infections are a significant concern. These infections can lead to device removal, negating the benefits and impacting patient outcomes. This review explores the risks and factors contributing to these infections and existing strategies to minimize them. These strategies encompass a multifaceted approach that considers patient-specific issues, environmental issues, device design and surgical techniques. However, despite these interventions, there is still a pressing need for further advancements in device infection prevention.

RECENT FINDINGS

Faster diagnostics, such as Raman spectroscopy, could enable early detection of infections. Additionally, biocompatible adjuncts like ultrasound-responsive microbubbles hold promise for enhanced drug delivery and biofilm disruption, particularly important as antibiotic resistance rises worldwide.

SUMMARY

By combining advancements in diagnostics, device design, and patient-specific surgical techniques, we can create a future where implantable urological devices offer men a significant improvement in quality of life with minimal infection risk.

Antimicrobial Resistance Studies Using Raman Spectroscopy on Clinically Relevant Bacterial Strains

There has been a steep rise in the emergence of antibiotic-resistant bacteria in the past few years. A timely diagnosis can help in initiating appropriate antibiotic therapy. However, conventional techniques for diagnosing antibiotic resistance are time-consuming and labor-intensive. Therefore, we investigated the potential of Raman spectroscopy as a rapid surveillance technology for tracking the emergence of antibiotic resistance. In this study, we used Raman spectroscopy to differentiate clinical isolates of antibiotic-resistant and -sensitive bacteria of Escherichia coli, Acinetobacter baumannii, and Enterobacter species. The spectra were collected with or without exposure to various antibiotics (ciprofloxacin, gentamicin, meropenem, and nitrofurantoin), each having a distinct mechanism of action. Ciprofloxacin- and meropenem-treated sensitive strains showed a decrease in the intensity of Raman bands associated with DNA (667, 724, 785, 1378, 1480, and 1575 cm^-1) and proteins (640 and 1662 cm^-1), coupled with an increase in the intensity of lipid bands (891, 960, and 1445 cm^-1). Gentamicin- and nitrofurantoin-treated sensitive strains showed an increase in the intensity of nucleic acid bands (668, 724, 780, 810, 1378, 1480, and 1575 cm^-1) while a decrease in the intensity of protein bands (640, 1003, 1606, and 1662 cm^-1) and the lipid band (1445 cm^-1). The Raman spectral changes observed in the antibiotic-resistant strains were opposite to that of antibiotic-sensitive strains. The Raman spectral data correlated well with the antimicrobial susceptibility test results. The Raman spectral dataset was used for partial least-squares (PLS) analysis to validate the biomarkers obtained from the univariate analysis. Overall, this study showcases the potential of Raman spectroscopy for detecting antibiotic-resistant and -sensitive bacteria.

An immunoresponsive three-dimensional urine-tolerant human urothelial model to study urinary tract infection

Introduction

Murine models of urinary tract infection (UTI) have improved our understanding of host-pathogen interactions. However, given differences between rodent and human bladders which may modulate host and bacterial response, including certain biomarkers, urothelial thickness and the concentration of urine, the development of new human-based models is important to complement mouse studies and to provide a more complete picture of UTI in patients.

Methods

We originally developed a human urothelial three-dimensional (3D) model which was urine tolerant and demonstrated several urothelial biomarkers, but it only achieved human thickness in heterogenous, multi-layered zones and did not demonstrate the comprehensive differentiation status needed to achieve barrier function. We optimised this model by altering a variety of conditions and validated it with microscopy, flow cytometry, transepithelial electrical resistance and FITC-dextran permeability assays to confirm tissue architecture, barrier integrity and response to bacterial infection.

Results

We achieved an improved 3D urine-tolerant human urothelial model (3D-UHU), which after 18-20 days of growth, stratified uniformly to 7-8 layers comprised of the three expected, distinct human cell types. The apical surface differentiated into large, CD227+ umbrella-like cells expressing uroplakin-1A, II, III, and cytokeratin 20, all of which are important terminal differentiation markers, and a glycosaminoglycan layer. Below this layer, several layers of intermediate cells were present, with a single underlying layer of CD271+ basal cells. The apical surface also expressed E-cadherin, ZO-1, claudin-1 and -3, and the model possessed good barrier function. Infection with both Gram-negative and Gram-positive bacterial classes elicited elevated levels of pro-inflammatory cytokines and chemokines characteristic of urinary tract infection in humans and caused a decrease in barrier function.

Discussion

Taken together, 3D-UHU holds promise for studying host-pathogen interactions and host urothelial immune response.

Endocytosis-mediated redistribution of antibiotics targets intracellular bacteria

The increasing emergence and dissemination of antibiotic resistance pose a severe threat to overwhelming healthcare practices worldwide. The lack of new antibacterial drugs urgently calls for alternative therapeutic strategies to combat multidrug-resistant (MDR) bacterial pathogens, especially those that survive and replicate in host cells, causing relapse and recurrence of infections. Intracellular drug delivery is a direct efficient strategy to combat invasive pathogens by increasing the accumulation of antibiotics. However, the increased accumulation of antibiotics in the infected host cells does not mean high efficacy. The difficulty of treatment lies in the efficient intracellular delivery of antibiotics to the pathogen-containing compartments. Here, we first briefly review the survival mechanisms of intracellular bacteria to facilitate the exploration of potential antibacterial targets for precise delivery. Furthermore, we provide an overview of endocytosis-mediated drug delivery systems, including the biomedical and physicochemical properties modulating the endocytosis and intracellular redistribution of antibiotics. Lastly, we summarize the targets and payloads of recently described intracellular delivery systems and their modes of action against diverse pathogenic bacteria-associated infections. This overview of endocytosis-mediated redistribution of antibiotics sheds light on the development of novel delivery platforms and alternative strategies to combat intracellular bacterial pathogens.

Effective Treatments of UTI—Is Intravesical Therapy the Future?

Urinary tract infection (UTI) afflicts millions of patients globally each year. While the majority of UTIs are successfully treated with orally administered antibiotics, the impact of oral antibiotics on the host microbiota is under close research scrutiny and the potential for dysbiosis is a cause for concern. Optimal treatment of UTI relies upon the selection of an agent which displays appropriate pharmacokinetic-pharmacodynamic (PK-PD) properties that will deliver appropriately high concentrations in the urinary tract after oral administration. Alternatively, high local concentrations of antibiotic at the urothelial surface can be achieved by direct instillation into the urinary tract. For antibiotics with the appropriate physicochemical properties, this can be of critical importance in cases for which an intracellular urothelial bacterial reservoir is suspected. In this review, we summarise the underpinning biopharmaceutical barriers to effective treatment of UTI and provide an overview of the evidence for the deployment of the intravesical administration route for antibiotics.

Advantages and Potential Benefits of Using Organoids in Nanotoxicology

Organoids are microtissues that recapitulate the complex structural organization and functions of tissues and organs. Nanoparticles have several specific properties that must be considered when replacing animal models with in vitro studies, such as the formation of a protein corona, accumulation, ability to overcome tissue barriers, and different severities of toxic effects in different cell types. An increase in the number of articles on toxicology research using organoid models is related to an increase in publications on organoids in general but is not related to toxicology-based publications. We demonstrate how the quantitative assessment of toxic changes in the structure of organoids and the state of their cell collections provide more valuable results for toxicological research and provide examples of research methods. The impact of the tested materials on organoids and their differences are also discussed. In conclusion, we highlight the main challenges, the solution of which will allow researchers to approach the replacement of in vivo research with in vitro research: biobanking and standardization of the structural characterization of organoids, and the development of effective screening imaging techniques for 3D organoid cell organization.

The clinical implications of bacterial pathogenesis and mucosal immunity in chronic urinary tract infection

Urinary tract infections (UTIs) exert a significant health and economic cost globally. Approximately one in four people with a previous history of UTI continue to develop recurrent or chronic infections. Research on UTI has primarily concentrated on pathogen behavior, with the focus gradually shifting to encompass the host immune response. However, these are centered on mouse models of Escherichia coli infection, which may not fully recapitulate the infective etiology and immune responses seen in humans. The emerging field of the urobiome also inadvertently confounds the discrimination of true UTI-causing pathogens from commensals. This review aims to present a novel perspective on chronic UTI by linking microbiology with immunology, which is commonly divergent in this field of research. It also describes the challenges in understanding chronic UTI pathogenesis and the human bladder immune response, largely conjectured from murine studies. Lastly, it outlines the shortcomings of current diagnostic methods in identifying individuals with chronic UTI and consequently treating them, potentially aggravating their disease due to mismanagement of prior episodes. This discourse highlights the need to consider these knowledge gaps and encourages more relevant studies of UTIs in humans.

Meta-Analysis of Drug Delivery Approaches for Treating Intracellular Infections

This meta-analysis aims to evaluate the trend, methodological quality and completeness of studies on intracellular delivery of antimicrobial agents. PubMed, Embase, and reference lists of related reviews were searched to identify original articles that evaluated carrier-mediated intracellular delivery and pharmacodynamics (PD) of antimicrobial therapeutics against intracellular pathogens in vitro and/or in vivo. A total of 99 studies were included in the analysis. The most commonly targeted intracellular pathogens were bacteria (62.6%), followed by viruses (16.2%) and parasites (15.2%). Twenty-one out of 99 (21.2%) studies performed neither microscopic imaging nor flow cytometric analysis to verify that the carrier particles are present in the infected cells. Only 31.3% of studies provided comparative inhibitory concentrations against a free drug control. Approximately 8% of studies, albeit claimed for intracellular delivery of antimicrobial therapeutics, did not provide any experimental data such as microscopic imaging, flow cytometry, and in vitro PD. Future research on intracellular delivery of antimicrobial agents needs to improve the methodological quality and completeness of supporting data in order to facilitate clinical translation of intracellular delivery platforms for antimicrobial therapeutics.