N-Acetylcysteine Protects Bladder Epithelial Cells from Bacterial Invasion and Displays Antibiofilm Activity against Urinary Tract Bacterial Pathogens

Mucolytic and antibiotic combination therapy using silica-based nanocarriers to eradicate Escherichia coli biofilms

This research provides new insights into the treatment of E. coli biofilm-related infections through the design of new antimicrobial nanoformulations based on mesoporous silica nanoparticles (MSNs) for mucolytic and antibiotic combination therapy against E. coli biofilms. The development of nanosystems with well-defined compartments to house and sequentially deliver different antimicrobial agents was carried out. A relatively simple and direct straightforward approach was carried out, consisting of loading MSNs with levofloxacin (LVX) by an impregnation method followed by external coating with a gelatin shell embedding a mixture of N-acetylcysteine (AC) plus LVX. Thus, the release of the mucolytic agent, AC, at the earliest stage causes disaggregation of the outer mucopolysaccharide layer of the mature E. coli biofilm, as confirmed by confocal laser scanning microscopy studies. This biofilm disruption effect facilitates the antimicrobial action of LVX, which is released in a more sustained manner over longer periods of time than AC, achieving a remarkable reduction (ca. 99.8%) of mature E. coli biofilms. These results are supported by the combined effect of AC and LVX strategically combined in the same nanocarrier. Preliminary in vitro studies with preosteoblastic cells point to the good biocompatibility of these nanosystems.

Unveiling the potential antibacterial action of acetylcysteine for managing Staphylococcus aureus wound infections: in vitro and in vivo study

The global propagation of infections is a massive challenge in managing infected wounds. One of the most widely detected bacteria in wounds is Staphylococcus aureus. These bacteria possess multiple virulence factors, like biofilm formation, which hinder antibiotic treatment. Accordingly, it is vital to explore alternative therapeutics for managing these infections. We estimated the antibacterial and antibiofilm actions of N-acetylcysteine (NC). It revealed antibacterial action with minimum inhibitory concentration values of 256-2048 µg/mL. In addition, NC revealed antibiofilm action as exposed phenotypically from crystal violet assay. The NC diminished the percentages of strong and moderate biofilm-forming isolates from 75% (18 isolates out of 24) to 33.34% (8 isolates out of 24). Scanning electron microscopy and qRT-PCR confirmed NC's antibiofilm action. Furthermore, the antibacterial consequence of NC was investigated in vivo employing a burn wound infection model. NC revealed a remarkable (p < 0.05) enhancement of the macroscopic wound healing and a decline of the bacterial count in the infected wound tissues compared with the positive control. The histopathological and immunohistochemical investigations elucidated a considerable improvement of the skin wound tissues of the NC-treated group with a decrease in the inflammatory marker immunostained cells (TNF-α, IL-6, and Il-1β) compared to the positive control. Besides, the qRT-PCR exposed an induced upregulation of the platelet-derived growth factor (PDGF) and fibronectin genes, which have a role in renovating skin tissues. From the previous outcomes, NC could be a healing agent, mainly in S. aureus-infected wounds. To our knowledge, this is the first time to report the wound healing potential of NC for S. aureus-infected wounds.

Influence of bacterial morphotype on urine culture and molecular epidemiological differences in Escherichia coli harboring bacterial morphotype-induced urinary tract infections

Bacteria that adhere to epithelial cells, form intracellular bacterial communities (IBCs), or transition to filamentous forms are referred to as morphotype-positive bacteria. Escherichia coli (E. coli) with this morphotype plays a critical role in urinary tract infections (UTIs), yet its impact on urine culture outcomes and molecular epidemiological characteristics remains unclear. In this retrospective study, we assessed the effect of bacterial morphotype on urine culture results and investigated the molecular differences between E. coli strains with and without this morphotype, using PCR and whole genome sequencing (WGS). We observed that E. coli with the morphotype-positive phenotype frequently appeared in urine sediments, leading to fewer colony-forming units (CFUs) in culture and contributing to false-negative results. However, vortexing the urine samples significantly increased CFUs, improving culture sensitivity. Additionally, E. coli with the positive morphotype carried more adhesion-related virulence genes (VGs), with the majority belonging to phylogenetic group B2. Whole genome sequencing further revealed a broader array of virulence genes in these strains. Our findings demonstrate that vortexing is an effective method to enhance urine culture positivity by releasing intracellular bacteria, and that morphotype-positive E. coli harbors a diverse set of virulence factors, indicating their potential high pathogenicity. These results highlight the importance of detecting bacterial morphotypes in urine samples for accurate UTI diagnosis and emphasize the need for increased attention to these highly virulent strains.

IMPORTANCE

Uropathogenic Escherichia coli (UPEC) is widely acknowledged as the primary pathogen responsible for urinary tract infections (UTIs). Following adherence to the epithelium, UPEC undergoes periodic morphological changes, such as filamentation, which not only contribute to immune evasion but also lead to false-negative results. This study focuses on three transient stages of UPEC morphological changes: adherence to the epithelium, formation of intracellular bacterial communities (IBCs), and the presence of filamentous UPEC. Any one of these characteristics is acceptable to classify UPEC strains as morphotype-positive UPEC. This study reported the prevalence of UPEC with the bacterial morphotype and established a direct relationship between urine culture and bacterial morphotype. The molecular epidemiological distinctions were both revealed. These findings provide further evidence of the necessary for bacterial morphotype detection, and greater attention should be given to E. coli harboring this bacterial morphotype.

N-Acetyl Cysteine and Vitamin C Modulate the Antibiotic Efficacy Against Escherichia coli Cells

Supplements with their own beneficial effect on hosts are consumed by us. N-acetyl cysteine (NAC) and Vitamin C (Vit C) are antioxidants and supplements, consumed for their beneficial properties. The present investigation evaluates the effect of their antioxidant property on antibiotic efficacy against Escherichia coli cells from different physiological states, including exponential and stationary-phase, cell aggregates, and in-vitro stress-induced persister cells. Survival was measured in cfu/mL by cfu (colony-forming unit) counting, with efficacy determined by log-fold change in survival by comparing CFUs in antibiotics alone and antibiotic + antioxidant combinations. Fluoroquinolones in the presence of NAC reduced ∼1 log CFUs of log-phase and persister cells, while Vit C reduced CFUs (∼1-3-log increase) of cells from all physiological states. Aminoglycosides results were inconclusive; streptomycin's activity declined (∼1-3-log increase in survival), whereas amikacin's activity potentiated (∼1-log reduction in cfu/mL). Rifampicin's showed reduced activity (∼2-3 log increase in survival) with Vit C in all the states and a ∼1-2 log increase with NAC, especially in cell aggregates and persisters. Beta-lactams activity showed variability, with amoxicillin and ampicillin not being influenced, but ceftriaxone showed significant reduction of efficacy (∼2-3-log increase in survival) in all the treatments. The findings suggest that the overall impact of antioxidants on antibiotic efficacy varies depending on the antibiotic class.

Beneficial Effects Induced by a Proprietary Blend of a New Bromelain-Based Polyenzymatic Complex Plus N-Acetylcysteine in Urinary Tract Infections: Results from In Vitro and Ex Vivo Studies

Background/Objectives: Urinary tract infections (UTIs) are infections that involve the urethra, bladder, and, in much more severe cases, even kidneys. These infections represent one of the most common diseases worldwide. Various pathogens are responsible for this condition, the most common being Escherichia coli (E. coli). Bromelain is a proteolytic complex obtained from the stem and stalk of Ananas comosus (L.) Merr. showing several beneficial activities. In addition to bromelain, N-acetylcysteine (NAC) has also been used. Methods: The purpose of this experiment was to evaluate the antibacterial, anti-motility, and anti-biofilm effects of a new polyenzymatic complex (DIF17BRO®) in combination with NAC (the Formulation) on various strains of E. coli isolated from patients with UTIs. Subsequently, the anti-inflammatory and antioxidant effects of the Formulation were studied in an ex vivo model of cystitis, using bladder samples from mice exposed to E. coli lipopolysaccharide (LPS). Results: Our results showed that the Formulation significantly affects the capability of bacteria to form biofilm and reduces the bacteria amount in the mature biofilm. Moreover, it combines the interesting properties of NAC and a polyenzyme plant complex based on bromelain in a right dose to affect the E. coli adhesion capability. Finally, the Formulation exhibited protective effects, as confirmed by the inhibitory activities on multiple inflammatory and oxidative stress-related pathways on bladder specimens exposed to LPS. Conclusions: This blend of active compounds could represent a promising and versatile approach to use to overcome the limitations associated with conventional therapies.

Exploring Immune Redox Modulation in Bacterial Infections: Insights into Thioredoxin-Mediated Interactions and Implications for Understanding Host-Pathogen Dynamics

Bacterial infections trigger a multifaceted interplay between inflammatory mediators and redox regulation. Recently, accumulating evidence has shown that redox signaling plays a significant role in immune initiation and subsequent immune cell functions. This review addresses the crucial role of the thioredoxin (Trx) system in the initiation of immune reactions and regulation of inflammatory responses during bacterial infections. Downstream signaling pathways in various immune cells involve thiol-dependent redox regulation, highlighting the pivotal roles of thiol redox systems in defense mechanisms. Conversely, the survival and virulence of pathogenic bacteria are enhanced by their ability to counteract oxidative stress and immune attacks. This is achieved through the reduction of oxidized proteins and the modulation of redox-sensitive signaling pathways, which are functions of the Trx system, thereby fortifying bacterial resistance. Moreover, some selenium/sulfur-containing compounds could potentially be developed into targeted therapeutic interventions for pathogenic bacteria. Taken together, the Trx system is a key player in redox regulation during bacterial infection, and contributes to host-pathogen interactions, offering valuable insights for future research and therapeutic development.

Antifungal chemicals promising function in disease prevention, method of action and mechanism

The increasing use of antimicrobial drugs has been linked to the rise of drug-resistant fungus in recent years. Antimicrobial resistance is being studied from a variety of perspectives due to the important clinical implication of resistance. The processes underlying this resistance, enhanced methods for identifying resistance when it emerges, alternate treatment options for infections caused by resistant organisms, and so on are reviewed, along with strategies to prevent and regulate the formation and spread of resistance. This overview will focus on the action mechanism of antifungals and the resistance mechanisms against them. The link between antibacterial and antifungal resistance is also briefly discussed. Based on their mechanism action, antifungals are divided into three distinct categories: azoles, which target the ergosterol synthesis; 5-fluorocytosine, which targets macromolecular synthesis and polyenes, which interact physiochemically with fungal membrane sterols. Antifungal resistance can arise through a wide variety of ways. Overexpression of the target of the antifungal drug, changes to the drug target, changes to sterol biosynthesis, decreased intercellular concentration of the target enzyme, and other processes. A correlation exists between the mechanisms of resistance to antibacterial and antifungals, despite the fact that the comparison between the two is inevitably constrained by various parameters mentioned in the review. Drug extrusion via membrane pumps has been thoroughly documented in both prokaryotic and eukaryotic cells, and development of new antifungal compounds and strategies has also been well characterized.

Antioxidant N-acetylcysteine removing ROS: an antifouling strategy inspired by mussels

Marine biofouling is a thorny issue that causes serious economic losses and adverse ecological impacts on marine ecosystems. Effective and promising antifouling strategies such as surface hydration, flow shear force, and lubricant injection have been developed to address this challenge. However, for the complex marine environment, they still appear inadequate. Mussels are a common fouling organism with strong surface adhesion ability. However, when hypoxia and the oxidative cross-linking reaction of 3,4-dihydroxy phenyl-L-alanine (DOPA) in the structure of adhesion proteins are disrupted, their adhesion ability will be greatly reduced. Inspired by this, we developed an effective antifouling strategy based on reactive oxygen species (ROS) scavenging using N-acetylcysteine (NAC) and evaluated its performance. As a ROS scavenger interfered with the oxidative cross-linking reaction of DOPA in an aqueous solution, the adhesion of DOPA was also affected on the surface of NAC functionalized polyvinyl chloride (PVC) (PVC-NAC). In addition, the colonization level of mussels and the adhesion rate of marine bacteria and benthic diatoms on PVC-NAC were low. The antifouling strategy proposed in this paper was eco-friendly and broad-spectrum, and may provide a new idea for solving marine biofouling and reducing the environmental and economic impacts of fouling organisms.

Fimbria targeting superparamagnetic iron oxide nanoparticles enhance the antimicrobial and antibiofilm activity of ciprofloxacin against quinolone-resistant E. coli

High quinolone resistance of Escherichia coli limits the therapy options for urinary tract infection (UTI). In response to the urgent need for efficient treatment of multidrug-resistant infections, we designed a fimbriae targeting superparamagnetic iron oxide nanoparticle (SPION) delivering ciprofloxacin to ciprofloxacin-resistant E. coli. Bovine serum albumin (BSA) conjugated poly(acrylic acid) (PAA) coated SPIONs (BSA@PAA@SPION) were developed for encapsulation of ciprofloxacin and the nanoparticles were tagged with 4-aminophenyl-α-D-mannopyrannoside (mannoside, Man) to target E. coli fimbriae. Ciprofloxacin-loaded mannoside tagged nanoparticles (Cip-Man-BSA@PAA@SPION) provided high antibacterial activity (97.1 and 97.5%, respectively) with a dose of 32 μg/mL ciprofloxacin against two ciprofloxacin-resistant E. coli isolates. Furthermore, a strong biofilm inhibition (86.9% and 98.5%, respectively) was achieved in the isolates at a dose 16 and 8 times lower than the minimum biofilm eradication concentration (MBEC) of ciprofloxacin. Weaker growth inhibition was observed with untargeted nanoparticles, Cip-BSA@PAA@SPIONs, confirming that targeting E. coli fimbria with mannoside-tagged nanoparticles increases the ciprofloxacin efficiency to treat ciprofloxacin-resistant E. coli. Enhanced killing activity against ciprofloxacin-resistant E. coli planktonic cells and strong growth inhibition of their biofilms suggest that Cip-Man-BSA@PAA@SPION system might be an alternative and/or complementary therapeutic option for the treatment of quinolone-resistant E. coli infections.

N-acetylcysteine prevents catheter occlusion and inflammation in catheter associated-urinary tract infections by suppressing urease activity

Introduction

Proteus mirabilis is a key pathobiont in catheter-associated urinary tract infections (CA-UTIs), which is well known to form crystalline biofilms that occlude catheters. Urease activity alkylates urine through the release of ammonia, consequentially resulting in higher levels of Mg2+ and Ca2+ and formation of crystals. In this study, we showed that N-acetyl cysteine (NAC), a thiol antioxidant, is a potent urease inhibitor that prevents crystalline biofilm formation.

Methods

To quantify urease activity, Berthelot's method was done on bacterial extracts treated with NAC. We also used an in vitro catheterised glass bladder model to study the effect of NAC treatment on catheter occlusion and biofilm encrustation in P. mirabilis infections. Inductively-coupled plasma mass spectrometry (ICP-MS) was performed on catheter samples to decipher elemental profiles.

Results

NAC inhibits urease activity of clinical P. mirabilis isolates at concentrations as low as 1 mM, independent of bacterial killing. The study also showed that NAC is bacteriostatic on P. mirabilis, and inhibited biofilm formation and catheter occlusion in an in vitro. A significant 4-8log10 reduction in viable bacteria was observed in catheters infected in this model. Additionally, biofilms in NAC treated catheters displayed a depletion of calcium, magnesium, or phosphates (>10 fold reduction), thus confirming the absence of any urease activity in the presence of NAC. Interestingly, we also showed that not only is NAC anti-inflammatory in bladder epithelial cells (BECs), but that it mutes its inflammatory response to urease and P. mirabilis infection by reducing the production of IL-6, IL-8 and IL-1b.

Discussion

Using biochemical, microbiological and immunological techniques, this study displays the functionality of NAC in preventing catheter occlusion by inhibiting urease activity. The study also highlights NAC as a strong anti-inflammatory antibiofilm agent that can target both bacterial and host factors in the treatment of CA-UTIs.

Preclinical Evaluation of Nitroxide-Functionalised Ciprofloxacin as a Novel Antibiofilm Drug Hybrid for Urinary Tract Infections

Urinary tract infections (UTIs) are the second most common bacterial infection with high recurrence rates and can involve biofilm formation on patient catheters. Biofilms are inherently tolerant to antimicrobials, making them difficult to eradicate. Many antibiofilm agents alone do not have bactericidal activity; therefore, linking them to antibiotics is a promising antibiofilm strategy. However, many of these hybrid agents have not been tested in relevant preclinical settings, limiting their potential for clinical translation. Here, we evaluate a ciprofloxacin di-nitroxide hybrid (CDN11), previously reported to have antibiofilm activity against uropathogenic Escherichia coli (UPEC) strain UTI89 in vitro, as a potential UTI therapeutic using multiple preclinical models that reflect various aspects of UTI pathogenesis. We report improved in vitro activity over the parent drug ciprofloxacin against mature UTI89 biofilms formed inside polyethylene catheters. In bladder cell monolayers infected with UTI89, treatment with CDN11 afforded significant reduction in bacterial titers, including intracellular UPEC. Infected mouse bladders containing biofilm-like intracellular reservoirs of UPEC UTI89 showed decreased bacterial loads after ex vivo bladder treatment with CDN11. Activity for CDN11 was reported across different models of UTI, showcasing nitroxide-antibiotic hybridization as a promising antibiofilm approach. The pipeline we described here could be readily used in testing other new therapeutic compounds, fast-tracking the development of novel antibiofilm therapeutics.

Novel Key Ingredients in Urinary Tract Health-The Role of D-mannose, Chondroitin Sulphate, Hyaluronic Acid, and N-acetylcysteine in Urinary Tract Infections (Uroial PLUS®)

Urinary tract infections represent a common and significant health concern worldwide. The high rate of recurrence and the increasing antibiotic resistance of uropathogens are further worsening the current scenario. Nevertheless, novel key ingredients such as D-mannose, chondroitin sulphate, hyaluronic acid, and N-acetylcysteine could represent an important alternative or adjuvant to the prevention and treatment strategies of urinary tract infections. Several studies have indeed evaluated the efficacy and the potential use of these compounds in urinary tract health. In this review, we aimed to summarize the characteristics, the role, and the application of the previously reported compounds, alone and in combination, in urinary tract health, focusing on their potential role in urinary tract infections.

Cranberry/Chondroitin Sulfate Co-precipitate as a New Method for Controlling Urinary Tract Infections

Urinary tract infections (UTI), which are among the most frequent cases of infectious diseases, mainly affect women. The most common treatment approach involves the use of antibiotics, although this solution is not always the most suitable, mainly because of the resistance that bacterial strains develop. Proanthocyanidins are a class of polyphenols, abundantly contained in cranberry extracts, which have shown beneficial effects in the treatment of urinary tract infections, due to their anti-adhesive properties toward bacteria, with respect to the membranes of the cells of the urothelium and intestine, thus reducing their virulence. In this work, we demonstrate via microscopy and scattering measurements how a mixture of cranberry and chondroitin sulfate can form a crosslinked structure with barrier properties. By using a design of experiment (DOE), we optimized the mass ratio to obtain a precipitate between cranberry extract and chondroitin sulfate in the presence of N-acetylcysteine and hyaluronic acid. By using transepithelial electrical resistance (TEER) chambers, we confirmed the barrier properties of the best mixture obtained with the DOE. Lastly, the antibiofilm action was investigated against five strains of Escherichia coli with different antibiotic sensitivity. The precipitate displayed a variable inhibitory effect in biofilm formation with major effects in UTI with an antibiotic resistance profile.

Effect of pH, Norepinephrine and Glucose on Metabolic and Biofilm Activity of Uropathogenic Microorganisms

Urinary tract infection (UTIs) aremainly caused by a number of anatomical and physiological dysfunctions, but there are also some iatrogenic factors, including the use of certain medications, that contribute to the development of UTIs. The virulence of bacteria that colonize the urinary tract may be modified by pH and by the presence of soluble substances in urine, such as norepinephrine (NE) and glucose. In this work, we studied the influence of NE and glucose across a range of pHs (5, 7, 8) on the biomass, matrix production and metabolism of uropathogenic strains of Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus and Enterococcus faecalis. We used Congo red and gentian violet to stain the extracellular matrix and biomass, respectively, of biofilms. The optical density of staining of the biofilms was measured using a multichannel spectrophotometer. The metabolic activity was analyzed by MTT assay. It was shown that NE and glucose stimulate biomass production both in the Gram-negative and Gram-positive uropathogens. The metabolic activity in the presence of glucose was higher at pH 5 for E. coli (in 4.0 ± 0.1 times), Ps. aeruginosa (in 8.2 ± 0.2 times) and Kl. pneumoniae (in 4.1 ± 0.2 times). Matrix production of Kl. pneumoniae increased under NE (in 8.2 ± 0.2 times) and in the presence of glucose (in 1.5 ± 0.3 times). Thus, NE and glucose in urine may lead to persistent UTI under patient stress and in the case of metabolic glucose disorders.

Investigating Biofilm Formation and Antibiofilm Activity Using Real Time Cell Analysis Method in Carbapenem Resistant Acinetobacter baumannii Strains

Acinetobacter baumannii is a significant nosocomial pathogen, with its biofilm forming capacity playing an important role in its pathogenicity. The fast and reliable detection of the biofilm formation and measurement of antibiofilm activity of various molecules are critical for combating A. baumannii infections. In this study, we aimed to detect biofilm formation by real time cell analyses (RTCA) method in clinical A. baumannii isolates and to investigate antibiofilm activities of tigecycline (TGC), N-acetylcysteine (NAC), and acetylsalicylic acid (ASA). The effect of the tested drugs on expressions of biofilm-related genes bap and csuE in clinical A. baumannii strains was also analyzed by real time quantitative reverse transcription polymerase chain reaction (RT-qPCR). Biofilm forming capacities for strong and weak biofilm producer A. baumannii strains were detected within 10 h by RTCA method (P < 0.05). We also observed that sub-minimum inhibitory concentrations of NAC + TGC and ASA + TGC combinations could significantly reduce biofilm formation and expression of biofilm-related genes in A. baumanii strains. No statistically significant activity of the tested drugs was detected against mature biofilms of the bacterial strains with the RTCA method. These results suggest that reproducible results on biofilm production capacity of A. baumannii strains and antibiofilm activities of various compounds can be obtained in a short time using RTCA method. Therefore, RTCA method seems to be a beneficial technique for biofilm detection and can help in combating A. baumannii infections by giving health providers the opportunity of implementing antibiofilm treatment strategies in a timely manner.

Understanding the Role of the Antioxidant Drug Erdosteine and Its Active Metabolite on Staphylococcus aureus Methicillin Resistant Biofilm Formation

Increasing numbers of researches have suggested that some drugs with reactive oxygen species (ROS)-mediated mechanisms of action modulate biofilm formation of some pathogenic strains. However, the full contribution of ROS to biofilm development is still an open question. In this paper, the correlations between the antioxidant drug Erdosteine (Er) and its active Metabolite I (Met I), ROS and biofilm development of two strains of methicillin resistant Staphylococcus aureus are presented. Experiments revealed that Er and Met I at 2 and 5 mg/L increased up to three orders of magnitude the number of biofilm-dwelling cells, while the content of ROS within the biofilms was reduced above the 87%, with a major effect of Met I in comparison to Er. Comparative proteomics showed that, 5 mg/L Met I modified the expression of 30% and 65% of total proteins in the two strains respectively. Some proteins involved in cell replication were upregulated, and a nitric oxide-based mechanism is assumed to modulate the biofilm development by changing quorum sensitive pathways. Additionally, several proteins involved in virulence were downregulated in the presence of Met I, suggesting that treated cells, despite being greater in number, might have lost part of their virulence.

Effects of Itxasol© Components on Gene Expression in Bacteria Related to Infections of the Urinary Tract and to the Inflammation Process

Urinary tract infections (UTIs) represent a health problem of the first magnitude since they affect large segments of the population, cause increased mortality and comorbidity, and have a high incidence of relapse. Therefore, UTIs cause a major socioeconomic concern. Current antibiotic treatments have various limitations such as the appearance of resistance to antibiotics, nephrotoxicity, and side effects such as gastrointestinal problems including microbiota alterations that contribute to increasing antibiotic resistance. In this context, Itxasol© has emerged, approved as an adjuvant for the treatment of UTIs. Designed with biomimetic principles, it is composed of arbutin, umbelliferon, and N-acetyl cysteine. In this work, we review the activities of these three compounds concerning the changes they produce in the expression of bacterial genes and those related to inflammation as well as assess how they are capable of affecting the DNA of bacteria and fungi.