Search Results (46)

Photodynamic inactivation (aPDI) involves the interaction of three components: non-toxic photosensitizer molecules (PS), low-intensity visible light, and molecular oxygen. This interaction leads to the generation of toxic reactive oxygen species. The present work demonstrated the efficacy of light-induced antimicrobial photodynamic inactivation against Pseudomonas aeruginosa and Pseudomonas putida using 5-aminolevulinic acid (5-ALA) as a prodrug to produce the photosensitizer protoporphyrin IX. The photoeradication efficiency of these pathogens under blue (405 nm; 45 mW cm⁻²) and red (635 nm; 53 mW cm⁻²) light was investigated. Results showed that at least 30 min of blue light irradiation was necessary to achieve a 99.999% reduction of P. aeruginosa, whereas red light was less effective. P. putida exhibited limited susceptibility under similar conditions. To enhance aPDI efficiency, exogenous glucose was added alongside 5-ALA, which significantly increased the photodynamic efficacy—particularly against P. aeruginosa—leading to complete eradication after just 5 min of exposure. Spectroscopic analyses confirmed that glucose increased the levels of protoporphyrin IX, which correlated with enhanced photodynamic efficacy. Furthermore, multiple aPDI exposure reduced key virulence factors, including alkaline protease activity, biofilm formation, and swarming motility (in P. aeruginosa). These findings suggest that 5-ALA-mediated photodynamic inactivation offers a promising strategy to improve efficacy against resistant Gram-negative pathogens. Full article

Skin infections are common in veterinary practice and are often treated with topical agents. Superficial pyoderma (superficial bacterial folliculitis) is a common cause of skin disease in dogs and a reason for treatment, most caused by Staphylococcus spp. strains. The frequent use of antibiotics contributes to the emergence of resistant bacterial strains, making antimicrobial resistance (AMR) one of the most important threats to human and animal health. For this reason, active natural compounds are increasingly being explored as alternative therapies. To contribute to the development of effective treatments for bacterial infectious diseases, researchers are looking for new antimicrobial agents. Topical drug action has many advantages as it avoids systemic reactions and ensures that the active substance reaches the site of the lesion directly. This study aimed to develop gelled dosage forms with propolis extract and to evaluate their antibacterial activity and the release of the active substances. Hydrogels, oleogels, and bigels enriched with eutectic propolis extract were produced. Deep eutectic solvents (DESs) were chosen as an effective tool to extract the active compounds of propolis and to improve their penetration into the skin. The pH values of the semi-solid pharmaceutical forms tested ranged from 3.3 to 6.4. Using modified Franz-type diffusion cells, the release of phenolic compounds from gels, oleogels, and bigels was assessed and quantified spectrophotometrically using the Folin–Ciocalteu method. The highest amount of active compounds was released from the hydrogels, while the lowest amount was released from the castor oil-based oleogel. The study used clinical and reference strains of bacteria. The antimicrobial activity of the gelled dosage forms with propolis extract was tested against six pathogenic bacterial species (S. aureus, S. agalactiae, B. cereus, E. faecalis, E. coli, Ps. aeruginosa) and one pathogenic fungus (C. albicans). The study’s results suggest that the propolis extract obtained by DES has significant antibacterial activity and is a promising component in skin formulations for the treatment of bacterial infections. Full article

Background/Objectives: Diabetic mouth ulcers are a pathological condition of the oral mucosa leading to increases in susceptibility to infection and prolonged wound healing time. Still, there is a lack of natural formulations for treating this condition. Our principal objective was to formulate solid lipid nanoparticles (SLNs) that contained Althaea officinalis (marshmallow) (M.) extract with clove oil (CO.), subsequently integrated into a collagen sponge for enhancing stability, solubility, sustained release, antimicrobial efficacy, and healing power when targeting diabetic oral ulcers. Methods: A factorial design of 34 trials was established to evaluate the influence of lipid concentration (A), SAA concentration (B), lipid type (C), and SAA type (D). The optimized M-CO-SLNs was selected using Design Expert^®, the based Poly dispersibility index (Y2), zeta potential (MV) (Y3), and encapsulation efficiency (%) (Y4). The optimized SLNs were integrated into a collagen sponge matrix and tested for their antibacterial and antifungal efficacy against Pseudomonas aeruginosa, Escherichia coli, and Candida albicans, respectively. Moreover, they were tested for their wound healing power in a diabetic mouth ulcer model. Results: The optimized formula (Run 16: 5% lipid concentration, 4% SAA concentration, capric acid) demonstrated P.S (110 ± 0.76 nm), ZP (−24 ± 0.32 mV), PDI (0.18 ± 0.05), and EE% (90 ± 0.65%.). The optimized M-CO-SLNs formula was incorporated into a cross-linked collagen sponge and showed superior antimicrobial efficacy, an increased swelling ratio, and was effective in an in vivo oral ulcer study, as evidenced by ELISA biomarkers, gene expression analysis, and histological analysis. Conclusions: M-CO-SLNs embedded in collagen sponges is a promising therapeutic formula for clinical application against diabetic mouth ulcers. Full article

The global rise in antimicrobial resistance, particularly among ESKAPE pathogens, has intensified the demand for alternative therapeutic strategies. Silver nanoparticles (AgNPs) have exhibited broad-spectrum antimicrobial activity and represent a promising approach to combat multidrug-resistant infections. This study aimed to synthesize and functionalize AgNPs using various polymeric agents—ethylene glycol (EG), polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and their combinations—and to evaluate their antimicrobial and antibiofilm efficacy against clinically relevant bacterial strains. AgNPs were synthesized via chemical reduction and functionalized as Ag@EG, Ag@PEG, Ag@EG/PVP, and Ag@PEG/PVP. A total of 68 clinical isolates—including Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa—were tested. Antimicrobial susceptibility was assessed using disc diffusion and broth microdilution assays, while antibiofilm activity was evaluated via the crystal violet method. Among all tested formulations, Ag@EG/PVP exhibited the highest antimicrobial and antibiofilm activity, with notably low minimum inhibitory concentrations (MIC₅₀) and minimum biofilm eradication concentrations (MBEC₅₀) for Ps. aeruginosa and K. pneumoniae. In contrast, AgNPs functionalized with PEG or EG alone showed limited efficacy. Biofilm-forming isolates, particularly Staphylococcus spp., required higher concentrations for inhibition. These results highlight the critical role of functionalization in modulating the antimicrobial properties of AgNPs, with Ag@EG/PVP demonstrating potent activity against both planktonic and biofilm-associated multidrug-resistant bacteria. Overall, this study supports further developing AgNPs-based formulations as adjuncts or alternatives to conventional antibiotics, particularly for managing biofilm-related infections. Future research should focus on formulation optimization, safety assessment, and translational potential. Full article

The study examined the sustained release of neem from the polymeric carrier system chitosan by varying the drug content, ionic strength of the release medium, and pH. Six different kinetic models, i.e., Korsmeyer–Peppas (KP), Peppas–Sahlin (PS), Higuchi, Hixson–Crowell, Zero order, and First order were used to investigate the drug release kinetics. Based on the R² values, the KP and PS models were chosen from the examined models to study the drug release mechanism from the chitosan biopolymer. The values found for model parameters n and m in the KP and PS models differ noticeably, suggesting that Fickian diffusion and Case II relaxation are important components of the neem release mechanism from chitosan. At lower ionic strengths and lower pH values, neem is released from the composite mostly by Fickian diffusion. The diphenyl-2-picrylhydrazyl assay served to assess the composite’s antioxidant properties. The composite’s antioxidant properties ranged from 3.56 ± 1.89% at 10 μg/mL to 51.28 ± 1.14% at 70 μg/mL. The ability of the composite to inhibit the denaturation of egg albumin was also tested and it ranged from 59.68 ± 0.93% at 25 μg/mL to 187.63 ± 3.53% at 1600 μg/mL. The drug composite has exhibited antibacterial activity against Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus, and proved to be highly effective against P. aeruginosa at lower concentrations and against S. aureus at higher concentrations. The resulting inhibition zones for P. aeruginosa at 5 and 10 mg/mL concentrations were 16.5 ± 2.25 mm, and 14.83 ± 0.6 mm, respectively, whereas for S. aureus, it was 16.67 ± 0.33 mm at 20 mg/mL. The neem–chitosan composite’s minimum inhibitory concentration/minimum bactericidal concentration ratio for K. pneumoniae, P. aeruginosa, and S. aureus was greater than 4, suggesting that they trigger bacteriostatic outcomes, whereas for E. coli, it was 4, which means that bactericidal effects were evident. Full article

This investigation studies the properties and composition of extracellular polymeric substances (EPS) of the four tolerant bacterial strains [NH (Cellulosimicrobium cellulans), TH, YH, and HE (Pseudomonas aeruginosa)] under perfluorobutanesulfonic acid (PFBS) stress. The strains were acquired from athickened sludge in a fluorine chemical park. Each strain’s EPS were isolated by heating and centrifugation, and their growth, metabolic activity, and EPS alteration research pre- and post-stress were assessed and compared. The strain type was identified by morphological observation and 16S rDNA gene sequence analysis. Under PFBS (100 μg·L⁻¹) stress, the four tolerant strains NH, TH, YH, and HE showed 38.10%, 29.26%, 35.92%, and 30.48% removal of PFBS on day 4, respectively, and the strain’s EPS had a substantial impact on main component protein (PR) and polysaccharide (PS) contents. The NH microorganism’s ability to metabolize organic matter was markedly stronger; it had a higher quantity, and its impact on main EPS content was greater than the other three tolerant strains. The three-dimensional excitation–emission matrix results showed marked alterations in tryptophan and aromatic protein peaks in the tolerant strain’s EPS. Furthermore, the FTIR analysis showed that the intensity of the functional groups in the proteins (-OH, C=O, -NH, and -CN) and the polysaccharides (-OH, C-O-C, and C-O) changed significantly. This investigation indicated that the proteins and polysaccharides of the tolerant strain’s EPS could provide more binding sites for PFBS adsorption, where the NH strain had the best biosorption capacity. This research provides a theoretical basis for elucidating efficient biosorbents. Full article

The objective of this study was to explore the preservation of food products through the co-fermentation of whole-plant cassava and Piper sarmentosum (PS) without additives. We assessed fermentation quality, antioxidant activity, bacterial community structure, function profile, and microbial ecological network features. Our results demonstrate that co-fermentation of whole-plant cassava with 10% PS significantly improves food quality. The co-fermented samples exhibited enhanced lactic acid concentrations and increased antioxidant activity, with reduced pH values and concentrations of acetic acid, butyric acid, and ammonia-N(NH₃-N) compared to whole-plant cassava fermented alone. In addition, PS addition also optimized microbial community structure by elevating the total abundance of lactic acid bacteria and influenced bacterial predicted functions. Furthermore, our analysis of co-occurrence networks reveals that co-fermentation impacts microbial network features, including module numbers and bacterial relative abundances, leading to altered complexity and stability of the networks. Moreover, out study also highlights the impact of ferment undesirable bacteria like Pseudomonas aeruginosa and unclassified_Muribaculaceae playing crucial roles in microbial network complexity and stability. These findings provide valuable insights into the anaerobic fermentation process and offers strategies for regulating food fermentation quality. Full article

Photodynamic therapy (PDT) has been based on using photosensitizers (PS) and applying light of a specific wavelength. When this technique is used for treating infections, it is known as antimicrobial photodynamic therapy (aPDT). Currently, the use of lighting sources for in vitro studies using aPDT is generally applied in multiwell cell culture plates; however, depending on the lighting arrangement, there are usually errors in the application of the technique because the light from a well can affect the neighboring wells or it may be that not all the wells are used in the same experiment. In addition, one must be awarded high irradiance values, which can cause unwanted photothermal problems in the studies. Thus, this manuscript presents an in vitro antimicrobial photodynamic therapy for a Pseudomonas aeruginosa (P. aeruginosa) and methicillin-resistant Staphylococcus aureus (MRSA) inhibition study using an arrangement of thermally isolated and independently illuminated green light source systems for eight tubes in vitro aPDT, determining the effect of the following factors: (i) irradiance level, (ii) exposure time, and (iii) Rose Bengal (RB) concentration (used as a PS), registering the Pseudomonas aeruginosa (P. aeruginosa) and methicillin-resistant Staphylococcus aureus (MRSA) inhibition rates. The results show that in the dark, RB had a poor antimicrobial rate for P. aeruginosa, finding the maximum inhibition (2.7%) at 30 min with an RB concentration of 3 µg/mL. However, by applying light in a correct dosage (time × irradiance) and the adequate RB concentration, the inhibition rate increased by over 37%. In the case of MRSA, there was no significant inhibition with RB in complete darkness and, in contrast, the rate was 100% for those experiments that were irradiated. Full article

In the quest to curtail the spread of healthcare-associated infections, this work showcases the fabrication of a cutting-edge antibacterial textile coating armoured with aggregation-induced emission photosensitisers (AIE PS) to prevent bacterial colonisation on textiles. The adopted methodology includes a multi-step process using plasma polymerisation and subsequent integration of AIE PS on their surface. The antibacterial effectiveness of the coating was tested against Pseudomonas aeruginosa and Staphylococcus aureus after light irradiation for 1 h. Furthermore, antibacterial mechanistic studies revealed their ability to generate reactive oxygen species that can damage bacterial cell membrane integrity. The results of this investigation can be used to develop ground-breaking explanations for infection deterrence, principally in situations where hospital fabrics play a critical part in the transmission of diseases. The antibacterial coating for textiles developed in this study holds great promise as an efficient strategy to promote public health and reduce the danger of bacterial diseases through regular contact with fabrics. Full article

SARS-CoV-2 has caused the most devastating pandemic of all time in recent human history. However, there is a serious paucity of high-quality data on aggravating factors and mechanisms of co-infection. This study aimed to identify the trending patterns of bacterial co-infections and types and associated outcomes in three phases of the pandemic. Using quality hospital data, we have investigated the SARS-CoV-2 fatality rates, profiles, and types of bacterial co-infections before, during, and after COVID-19 vaccination. Out of 389 isolates used in different aspects, 298 were examined before and during the pandemic (n = 149 before, n = 149 during). In this group, death rates were 32% during compared to only 7.4% before the pandemic with significant association (p-value = 0.000000075). However, the death rate was 34% in co-infected (n = 170) compared to non-co-infected patients (n = 128), indicating a highly significant value (p-value = 0.00000000000088). However, analysis of patients without other serious respiratory problems (n = 28) indicated that among the remaining 270 patients, death occurred in 30% of co-infected patients (n = 150) and only 0.8% of non-co-infected (n = 120) with a high significant p-value = 0.00000000076. The trending patterns of co-infections before, during, and after vaccination showed a significant decline in Staphylococcus aureus with concomitant peaks in Gram negatives n = 149 before/n = 149 during, including Klebsiella pneumonian = 11/49 before/during, E. coli n = 10/24, A. baumannii n = 8/25, Ps. aeruginosa n = 5/16, and S. aureus 13/1. Nevertheless, in the post-vaccination phase (n = 91), gender-specific co-infections were examined for potential differences in susceptibility. Methicillin-resistant S. aureus dominated both genders followed by E. coli in males and females, with the latter gender showing higher rates of isolations in both species. Klebsiella pneumoniae declined to third place in male patients. The drastic decline in K. pneumoniae and Gram negatives post-vaccination strongly implied a potential co-protection in vaccines. Future analysis would gain more insights into molecular mimicry. Full article

The development of new approaches for the treatment of the increasingly antibiotic-resistant pathogen Pseudomonas aeruginosa was targeted by enhancing the effect of local antimicrobial photodynamic therapy (aPDT) using poly(ethylene glycol)-block-poly(lactic acid) (PEG₁₁₄-block-PLA_x) nanocarriers that were loaded with a ruthenium-based photosensitizer (PS). The action of tris(1,10-phenanthroline) ruthenium (II) bis(hexafluorophosphate) (RuPhen3) encapsulated in PEG₁₁₄-block-PLA_x micelles and vesicles was shown to result in an appreciable aPDT inactivation efficiency against planktonic Pseudomonas aeruginosa. In particular, the encapsulation of the PS, its release, and the efficiency of singlet oxygen (¹O₂) generation upon irradiation with blue light were studied spectroscopically. The antimicrobial effect was analyzed with two strains of Pseudomonas aeruginosa. Compared with PS-loaded micelles, formulations of the PS-loaded vesicles showed 10 times enhanced activity with a strong photodynamic inactivation effect of at least a 4.7 log reduction against both a Pseudomonas aeruginosa lab strain and a clinical isolate collected from the lung of a cystic fibrosis (CF) patient. This work lays the foundation for the targeted eradication of Pseudomonas aeruginosa using aPDT in various medical application areas. Full article

The emergence of phage-resistant bacterial strains is one of the biggest challenges for phage therapy. However, the emerging phage-resistant bacteria are often accompanied by adaptive trade-offs, which supports a therapeutic strategy called “phage steering”. The key to phage steering is to guide the bacterial population toward an evolutionary direction that is favorable for treatment. Thus, it is important to systematically investigate the impacts of phages targeting different bacterial receptors on the fitness of the bacterial population. Herein, we employed 20 different phages to impose strong evolutionary pressure on the host Pseudomonas aeruginosa PAO1 and examined the genetic and phenotypic responses of their phage-resistant mutants. Among these strains with impaired adsorptions, four types of mutations associated with bacterial receptors were identified, namely, lipopolysaccharides (LPSs), type IV pili (T4Ps), outer membrane proteins (OMPs), and exopolysaccharides (EPSs). PAO1, responding to LPS- and EPS-dependent phage infections, mostly showed significant growth impairment and virulence attenuation. Most mutants with T4P-related mutations exhibited a significant decrease in motility and biofilm formation ability, while the mutants with OMP-related mutations required the lowest fitness cost out of the bacterial populations. Apart from fitness costs, PAO1 strains might lose their resistance to antibiotics when counteracting with phages, such as the presence of large-fragment mutants in this study, which may inspire the usage of phage–antibiotic combination strategies. This work provides methods that leverage the merits of phage resistance relative to obtaining therapeutically beneficial outcomes with respect to phage-steering strategies. Full article

Pseudomonas aeruginosa (PsA) is an opportunistic bacterial pathogen that causes life-threatening infections in individuals with compromised immune systems and exacerbates health concerns for those with cystic fibrosis (CF). PsA rapidly develops antibiotic resistance; thus, novel therapeutics are urgently needed to effectively combat this pathogen. Previously, we have shown that a novel cationic Zinc (II) porphyrin (ZnPor) has potent bactericidal activity against planktonic and biofilm-associated PsA cells, and disassembles the biofilm matrix via interactions with eDNA In the present study, we report that ZnPor caused a significant decrease in PsA populations in mouse lungs within an in vivo model of PsA pulmonary infection. Additionally, when combined with an obligately lytic phage PEV2, ZnPor at its minimum inhibitory concentration (MIC) displayed synergy against PsA in an established in vitro lung model resulting in greater protection of H441 lung cells versus either treatment alone. Concentrations above the minimum bactericidal concentration (MBC) of ZnPor were not toxic to H441 cells; however, no synergy was observed. This dose-dependent response is likely due to ZnPor’s antiviral activity, reported herein. Together, these findings show the utility of ZnPor alone, and its synergy with PEV2, which could be a tunable combination used in the treatment of antibiotic-resistant infections. Full article

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. Full article

Developing new broad-spectrum antimicrobial strategies, as alternatives to antibiotics and being able to efficiently inactivate pathogens without inducing resistance, is one of the main objectives in public health. Antimicrobial photodynamic therapy (aPDT), based on the light-induced production of reactive oxygen species from photosensitizers (PS), is attracting growing interest in the context of infection treatment, also including biofilm destruction. Due to the limited photostability of free PS, delivery systems are increasingly needed in order to decrease PS photodegradation, thus improving the therapeutic efficacy, as well as to reduce collateral effects on unaffected tissues. In this study, we propose a photosensitizing nanosystem based on the cationic porphyrin 5,10,15,20-tetrakis (N-methyl- 4-pyridyl)-21H,23H-porphyrin (TMPyP), complexed with the commerical sulfobutylether-beta-cyclodextrin (CAPTISOL^®), at a 1:50 molar ratio (CAPTISOL^®/TMPyP)_{50_1}. Nanoassemblies based on (CAPTISOL^®/TMPyP)_{50_1} with photodynamic features exhibited photo-antimicrobial activity against Gram-negative and Gram-positive bacteria. Moreover, results from P. aeruginosa reveal that CAPTISOL^® alone inhibits pyocyanin (PYO) production, also affecting bacterial biofilm formation. Finally, we obtained a synergistic effect of inhibition and destruction of P. aeruginosa biofilm by using the combination of CAPTISOL^® and TMPyP. Full article