Search Results (804)

This study addresses the challenge of rapidly and accurately distinguishing zones of microbial activity from antibiotic inhibition zones in Petri dishes. We propose a laser speckle imaging technique enhanced with subpixel correlation analysis to monitor dynamic changes in the inhibition zone surrounding an antibiotic disc. This method provides faster results compared to the standard disk diffusion assay recommended by EUCAST. To enable automated analysis, we used machine learning algorithms for classifying areas of bacterial or fungal activity versus inhibited growth. Classification is performed over short time windows (e.g., 1 h), supporting near-real-time assessment. To further improve accuracy, we introduce a correction method based on the known spatial dynamics of inhibition zone formation. The novelty of the study lies in combining a speckle imaging subpixel correlation algorithm with ML classification and with pre- and post-processing. This approach enables early automated assessment of antimicrobial effects with potential applications in rapid drug susceptibility testing and microbiological research. Full article

Background/Objectives: Polymeric monoaxial nanofibers are gaining prominence due to their numerous applications, particularly in functional scenarios such as wound management. The study successfully developed and built a special-purpose vessel and device for fabricating polymeric nanofibers. Fabrication of composite scaffolds from piezoelectric poly(vinylidenefluoride-trifluoroethylene) copolymer (PVDF-TrFE) nanofibers encapsulated with myrrh extract was investigated. Methods: The gyrospun nanofibers were characterized using SEM, EDX, FTIR, XRD, and TGA to assess the properties of the composite materials. The study also investigated the release profile of myrrh extract from the nanofibers, demonstrating its potential for sustained drug delivery. The composite’s antimicrobial properties were evaluated using the disc diffusion method against various pathogenic microbes, showcasing their effectiveness. Results: It was found that an 18% (w/v) PVDF-TrFE concentration produces the best fiber mats compared to 20% and 25%, resulting in an average fiber diameter of 411 nm. Myrrh extract was added in varying amounts (10%, 15%, and 20%), with the best average fiber diameter identified at 10%, measuring 436 nm. The results indicated that the composite nanofibers were uniform, bead-free, and aligned without myrrh. The study observed a cumulative release of 79.66% myrrh over 72 h. The release profile showed an initial burst release of 46.85% within the first six hours, followed by a sustained release phase. Encapsulation efficiency was 89.8%, with a drug loading efficiency of 30%. Antibacterial activity peaked at 20% myrrh extract. S. mutans was the most sensitive pathogen to myrrh extract. Conclusions: Due to the piezoelectric effect of PVDF-TrFE and the significant antibacterial activity of myrrh, the prepared biohybrid nanofibers will open new avenues toward tissue engineering and wound healing applications. Full article

Implementing a computationally efficient numerical model for a single streamer discharge is essential to understand the complex processes such as lightning initiation and electrical discharges in high voltage systems. In this paper, we present a streamer discharge simulation in air, by solving one-dimensional (1D) drift diffusion reaction (DDR) equations for charged species with the disc approximation for electric field. A recently developed fourth-order space and time-centered implicit finite difference method (FDM) with a flux-corrected transport (FCT) method is applied to solve the DDR equations, followed by a comparative simulation using the well-established explicit FDM with FCT. The results demonstrate good agreement between implicit and explicit FDMs, verifying their reliability for streamer modeling. The total electrons, total charge, streamer position, and hence the streamer bridging time obtained using the FDMs with FCT agree with the same streamer computed in the literature using different numerical methods and dimensions. The electric field is obtained with good accuracy due to the inclusion of image charges representing the electrodes in the disc method. This accuracy can be further improved by introducing more image charges. Both implicit and explicit FDMs effectively capture the key streamer behavior, including the variations in charged particle densities and electric field. However, the implicit FDM is computationally more efficient. Full article

Background/Objectives: The main objective of this research work was to identify and determine the antibiotic resistance of the false-positive isolates on chromogenic agar when analyzing Salmonella in chicken meat. Methods: A total of 234 samples of chicken meat (carcasses, cuts and preparations) were studied using buffered peptone water for primary enrichment, Rappaport–Vassiliadis soy broth for secondary enrichment and Salmonella Chromogen Agar Set as a selective solid medium. Colonies with a morphology characteristic of Salmonella (one isolate per sample) were identified by matrix-assisted laser desorption ionization and time-of-flight mass spectrometry (MALDI-TOF). Results: Colonies with a characteristic morphology of Salmonella were detected in 71 samples. Only five isolates (7.0% of the total) corresponded to the genus Salmonella. Other genera detected were Hafnia (three isolates; 4.2% of the total), Escherichia (22; 31.0%), Klebsiella (19; 26.8%), Proteus (6; 8.5%) and Pseudomonas (16; 22.5%). The 66 isolates of these last five genera were tested for susceptibility to a panel of 42 antibiotics of clinical importance by disc diffusion. All isolates presented multiple resistances, to between 4 and 29 antibiotics, all of them having a multi drug-resistant (MDR) phenotype except for one Pseudomonas strain, with an extensively drug-resistant (XDR) phenotype. Conclusions: These results highlight the low selectivity of this method, with the specific culture media under test, for the detection of Salmonella in poultry meat. The considerable prevalence of antibiotic resistance observed suggests a need to improve control measures throughout the poultry meat production chain to prevent this food from becoming a reservoir of bacteria with resistance to multiple antibiotics. Full article

This study on the isolation, identification, and characterization of the probiotic properties of lactic acid bacterial strains from the rose blossom of Rosa damascena Mill. (R. damascena) is crucial for discovering novel, plant-derived probiotics with potential health benefits and applications in food, medicine, and cosmetics. Nine lactic acid bacterial (LAB) strains were isolated from rose blossom of R. damascena, and they were identified to the species level by applying physiological and biochemical (API 50 CHL), and molecular genetic (16S rRNA gene sequencing) methods. The isolates were identified as belonging to the Lactobacillus helveticus, Lactobacillus acidophilus, and Lactiplantibacillus plantarum species. Some probiotic properties of the newly isolated and identified LAB strains were examined: their antibacterial activity against pathogens by the agar well diffusion method, and their antibiotic resistance profile by the agar paper disc diffusion method. The LAB strains studied demonstrated significant antibacterial activity against the Escherichia coli, Staphylococcus aureus, Salmonella Abony, Proteus vulgaris, Listeria monocytogenes, and Enterococcus faecalis pathogens and were resistant to most of the antibiotics used in clinical practice, which in turn suggested the possibility of their joint inclusion in therapy, in the composition of probiotic preparations. A batch fermentation process was conducted with Lactiplantibacillus plantarum 5/20, and the kinetic parameters of the batch fermentation process were determined in order to obtain a concentrate with a high viable cell count (10¹³CFU/cm³). The resultant concentrate was freeze-dried, and freeze-dried preparations with a high viable cell count (over 10¹² CFU/g) were obtained. Research on LAB strains isolated from R. damascena could reveal valuable LAB strains with significant probiotic properties. These strains will be suitable for various applications in the composition of starter cultures for functional beverages and foods, as well as probiotic preparations, showcasing the untapped potential of plant-associated microbiota. Full article

Background/Objectives: The main objective was to evaluate and compare the antifungal efficacy against Candida spp. in commercially available mouthwashes distributed in the European market. Indeed, the solution to emerging infectious diseases may no longer lie in costly new drug development but rather in unlocking the untapped potential of existing substances. Materials and Methods: Eighteen mouthwashes, chosen based on their composition, were tested in vitro against ten Candida strains, including clinical isolates of oral origin and reference strains, in both planktonic and biofilm forms. The antifungal susceptibility testing was conducted using the European Committee on Antimicrobial Susceptibility Testing (EUCAST) disc diffusion method and the evaluation of the kinetic growth in planktonic Candida. Biofilm reduction was determined by the evaluation of the minimal biofilm eradication concentration (MBEC). Scanning electron microscopy (SEM) analysis was performed to evaluate potential morphological alterations of Candida biofilms. Results: Most mouthwashes effectively reduced biomass production and colony-forming unit (CFU) count. Parodontax Extra showed the highest efficacy. In the disc diffusion assay, Gum Paroex 0.12% exhibited the largest average inhibition zone diameter. Some unusual trends in the data may be explained by a higher reaction of fungal cells and the release of excess biomass during co-incubation in higher concentration of mouthwashes. SEM images revealed significant morphological alterations. Conclusion: Mouthwashes containing chlorhexidine digluconate, either alone or in combination with cetylpyridinium chloride and other active compounds, emerged as a common factor among the most efficacious formulations. In vivo studies will be essential to validate these findings, but mouthwashes may serve as a valuable adjuvant in the treatment of oral candidiasis. Full article

The increasing resistance of microorganisms to currently used antimicrobials requires the urgent development of new effective treatments. Plant-based natural products can be an alternative solution. The aerial plant parts of the cranberry (Vaccinium macrocarpon) present a potential new source of antimicrobial secondary metabolites. Volatile essential oils were extracted from Stevens, Early Black, and Mullica Queen variety plants by steam distillation (SD) and the Clevenger method (CM), and their profiles were characterized by GC-MS. The extracts and two identified constituents, cinnamaldehyde and terpineol, were screened by the disc diffusion assay against Gram-positive B. cereus ATCC 11778 and S. aureus ATCC 25923 and Gram-negative bacteria E. coli ATCC 25922, P. aeruginosa ATCC 27853, and C. albicans ATCC 14053. Radical scavenging antioxidant activity was also determined using the DPPH assay. The CM extracts were rich in fatty acids, sesquiterpenes, and diterpenes, whereas the SD extracts contained more aldehydes, monoterpenes, and phenylpropanoids. All volatile extracts showed promising antioxidant activity; leaf extract activity was significantly higher than the vine (p < 0.05). The CM leaf and vine extracts exhibited antimicrobial activity against B. cereus, S. aureus, E. coli, and C. albicans compared to the SD, and the leaf extracts were more effective than the vine extracts. Individual constituents of leaf and vine extracts, cinnamaldehyde and α-terpineol, also showed antimicrobial activity against these organisms. The active constituents of the CM extracts are yet to be identified. A multivariate analysis revealed a particular pattern of inhibition of the tested organisms. Based on our results, cranberry volatile extracts have potential for future valorization as antibacterials, antifungals, and antioxidants. Full article

Background: Nowadays, the microbial degradation of cellulose represents a new perspective for reducing cellulose waste from industry and households and at the same time obtaining energy sources. Methods: We isolated and enriched two aerobic (at 37 °C and 50 °C) and one anaerobic microbial consortium from an anaerobic bioreactor for biogas production by continuous subculturing on peptone cellulose solution (PCS) medium supplemented with 0.3% treated or untreated Whatman filter paper under static conditions. Samples were taken every 7 days until day 21 to determine the percentage of cellulose biodegradation. We determined the antimicrobial resistance of aerobic and anaerobic consortia and some single colonies by disc diffusion method, against 42 clinically applied antibiotics. PCR analyses were performed to search for the presence of eight genes for cellulolytic activity and nine genes for antibiotic resistance. By metagenomics analysis, the bacterial and fungal genus distributions in the studied populations were determined. Results: Aerobes cultured at 50 °C degraded cellulose to the greatest extent (47%), followed by anaerobes (24–38%) and aerobes (8%) cultured at 37 °C. The bacterial sequence analysis showed that the dominant phyla are Bacillota and Bacteroidetes and genera—Paraclostridium, Defluvitalea, Anaerobacillus, Acetivibrio, Lysinibacillus, Paenibacillus, Romboutsia, Terrisporobacter, Clostridium, Sporanaerobacter, Lentimicrobium, etc. in a different ratio depending on the cultivation conditions and the stage of the process. Some of these representatives are cellulolytic and hemicellulolytic microorganisms. We performed lyophilization and proved that it is suitable for long-term storage of the most active consortium, which degrades even after the 10th re-inoculation for a period of one year. We proved the presence of ssrA, ssrA BS and blaTEM genes. Conclusions: Our findings demonstrated the potential utility of the microbial consortium of anaerobes in the degradation of waste lignocellulose biomass. Full article

Background: Animal-associated antimicrobial-resistant staphylococci pose a One Health concern, as they can spread into the environment and cause serious infections. Yet, donkeys in Nigeria have been largely overlooked as potential reservoirs of these pathogens. Aim/Objectives: To isolate Staphylococcus aureus from donkeys in Obollo-Afor, southeast Nigeria, assess their antimicrobial resistance profiles, and evaluate their virulence potential. Materials and Methods: Staphylococci were isolated from the nasal swabs of 250 donkeys, using mannitol salt agar, confirmed biochemically, with Staphylococcus aureus identified via a latex agglutination test and mass spectrometry. The resistance profiles of the isolates, including in regard to methicillin, inducible clindamycin, and β-lactamase production, were determined using disc diffusion, while vancomycin resistance was assessed through the use of agar dilution. The virulence factors were evaluated phenotypically. Results: Of the 250 samples, 11 (4.4%) contained S. aureus and 239 (95.6%) grew other Staphylococcus species. The resistance rates of the 11 S. aureus isolates to gentamicin, penicillin, tigecycline, cefoxitin, linezolid, and chloramphenicol were 45.5%, 66.7%, 54.5%, 27.3%, 36.4%, and 18.1%, respectively. The phenotypic methicillin-resistant S. aureus prevalence was 1.2%. Additionally, 23.5% of the S. aureus isolates were multidrug resistant, with a mean antibiotic resistance index of 0.25. All the S. aureus isolates exhibited virulence factors like clumping factor expression, catalase, caseinase, lecithinase, and gelatinase activity, while the occurrence of haemagglutinin, biofilm, pellicle, and hemolysin occurred in 27.3%, 54.5%, 36.4%, 72.2%, respectively. Conclusion: Although a small percentage of donkeys in Nigeria may harbor S. aureus, these animals are potentially spreading antimicrobial resistance, including multidrug and methicillin resistance, to humans and the environment. Full article

This in vitro study evaluated the effects of incorporating quercetin (QC) at varying concentrations (0.25%, 0.5%, and 1%) into a 35% hydrogen peroxide (H₂O₂) bleaching gel on esthetic outcomes, enamel hardness and roughness, and H₂O₂ transamelodentinal diffusion. Bovine enamel/dentin discs (n = 180; 12/per group for each analysis) were allocated into five groups: (1) negative control (NC), (2) 35% H₂O₂ (HP), (3) HP + 0.25% QC, (4) HP + 0.5% QC, and (5) HP + 1% QC. Treatments were applied for 40 min per session across three sessions with 7-day intervals. Color changes were evaluated using the CIELab* color system (ΔE_ab), with further analysis performed using the CIEDE2000 formula (ΔE₀₀) and the whitening index (ΔWI_D). Enamel surface hardness, roughness, cross-sectional hardness, and H₂O₂ diffusion were also evaluated. Data were analyzed using ANOVA, followed by the Student–Newman–Keuls test, with statistical significance set at p < 0.05. All experimental gels resulted in significant color changes (p < 0.001), with similar ΔE_ab, ΔE₀₀, and ΔWI_D across QC groups. The HP group showed greater reductions in hardness and increased roughness compared to others (p < 0.0001), while the HP/1%QC group resulted in no statistically significant alterations under the tested conditions. H₂O₂ diffusion was significantly greater in the HP group, while it was notably lower in the HP/1%QC group (p < 0.05). The incorporation of 1% quercetin into a 35% H₂O₂ gel maintains its bleaching efficacy while protecting enamel properties and reducing hydrogen peroxide diffusion. Quercetin-enriched H₂O₂ gels may enhance bleaching safety by protecting dental tissues while maintaining esthetic benefits. 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

Background/Objectives: This study investigates the phytochemical profile, essential oil composition, and bioactivities—including antioxidant, antimicrobial, antibio-film, and anti-quorum sensing (QS) activities—of four Heracleum L. species (H. crenatifolium Boiss, H. paphlagonicum Czeczott, H. sphondylium subsp. montanum Schleich. ex Gaudin, and H. pastinacifolium subsp. incanum (Boiss. & A.Huet) P.H.Davis). Methods: Total phenolic and flavonoid contents were quantified using the Folin–Ciocalteu and aluminum chloride colorimetric methods, respectively. Essential oils were extracted by hydrodistillation and analyzed via Gas Chromatography–Flame Ionization Detector (GC–FID) and Gas Chromatography–Mass Spectrometry (GC–MS), while Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) evaluated chemical variability among the species. Antioxidant activities were assessed using DPPH and ABTS free radical scavenging assays. Antimicrobial activity was assessed using the broth microdilution method to determine Minimum Inhibitory Concentration (MIC) values, while antibiofilm activity was evaluated using an in vitro microplate-based biofilm model against Pseudomonas aeruginosa PAO1. Anti-QS activity was analyzed using a disc diffusion assay with Chromobacterium violaceum ATCC 12472 as the reporter strain. Results: It was observed that the amounts of total phenolic compounds and total flavonoids were higher in root extracts than in aerial parts extracts for the four species in this study (H. sphondylium subsp. montanum excluding phenolic content). In the analysis of essential oil, it was determined that the major component in the roots was mostly myristicin, and in the fruits it was mostly octyl acetate. Phenolic and flavonoid contents were positively correlated with antioxidant activity. Methanol and n-hexane extracts of H. pastinacifolium (aerial parts) and n-hexane extracts of H. paphlagonicum (root) exhibited notable antimicrobial activity, primarily against Gram-positive bacteria, but none of the extracts showed activity against Klebsiella pneumoniae ATCC 13383 or P. aeruginosa ATCC 27853. Among methanol extracts, H. pastinacifolium (aerial parts) exhibited the highest antibiofilm activity (73.2%), while H. paphlagonicum (aerial parts) showed the highest activity among n-hexane extracts (75.5%). All n-hexane extracts exhibited anti-QS activity, whereas the methanol extracts showed no activity. Conclusions: These findings underscore the chemical diversity and bioactive potential of Heracleum species, contributing to the chemotaxonomic understanding of the genus and supporting their potential applications in medicine and industry. To our knowledge, this is the first study that reveals the antibiofilm and anti-QS properties of these Heracleum species. Full article

Introduction: Antimicrobial resistance (AMR) is a critical global public health issue, leading to prolonged illness, increased morbidity and mortality, and rising healthcare costs. The effectiveness of antibiotics is diminishing due to the emergence of resistant bacterial strains. This study aimed to determine the bacterial profile and AMR patterns of clinical isolates at Uttara Adhunik Medical College Hospital (UAMCH), Dhaka. Methods: A retrospective study was conducted at UAMCH from January 2017 to December 2019. A total of 32,187 clinical specimens (urine, blood, stool, wound swabs/pus, and sputum) were processed, of which 4232 yielded positive cultures. Bacterial identification followed standard bacteriological methods, and antibiotic susceptibility was assessed using the Kirby–Bauer disc diffusion method per CLSI guidelines. Data analysis was conducted using WHONET and QAAPT. Results: The highest proportion of positive cultures was from urine (47.5%), followed by blood (35.0%) and wound swabs/pus (10.1%). The most common isolates were Escherichia coli (37.2%), Salmonella typhi (25.7%), and Klebsiella sp. (11.5%). Gram-negative bacteria showed high resistance to commonly used antibiotics such as amoxicillin/clavulanic acid, cefixime, and ceftriaxone, while the resistance rates were lower for gentamicin, amikacin, and meropenem. However, Acinetobacter sp. exhibited alarming resistance to all tested antibiotics. Conclusions: This study highlights concerning resistance patterns among bacterial isolates, emphasizing the need for ongoing AMR surveillance to inform treatment strategies and improve patient care in Bangladesh. Full article

Pathogenic Escherichia coli can cause a variety of intestinal and extra-intestinal infections in humans and animals. The availability and subsequent misuse of antimicrobials, especially in poultry production systems, has contributed immensely to the emergence and spread of multidrug-resistant E. coli. This study investigated the genotypic characterization of colistin-resistant E. coli and selected antimicrobial-resistance encoding genes along with their phenotypic resistant pattern and the multiple antimicrobial resistant (MAR) index from village chickens in Kelantan. Sixty E. coli isolates obtained from a previous study’s stock culture were enriched and analyzed using routine microbiological methods: Kirby–Bauer disc diffusion method, minimum inhibitory concentration (MIC), and PCR amplification of E. coli species-specific and multidrug-resistance mcr-positive E. coli. All the isolates were confirmed as E. coli and 16.6% (10/60) were positive for mcr. Five isolates were positive for mcr-1, three for mcr-4, and two for mcr-9. The mcr-positive isolates showed varying degrees of resistance to different antimicrobials. The isolates were resistant to gentamicin (100%), chloramphenicol (100%), and tetracycline (89.4%) and susceptible to ceftaxidime (2.26%) and imipenem (18%). Furthermore, 100%, 94.7%, and 89.4% of isolates from village chickens belonged to phylogroup C, B2, and E, while 21.0% and 42.1% of the isolates belonged to phylogroup A and B1, respectively. Sequence types (STs) of selected E. coli isolates were further analyzed using multi-locus sequence typing, and 10 different STs were identified. This study showed the emerging threats of multidrug-resistant mcr-positive E. coli gene in village chickens that are believed to be raised with minimal or no antibiotics. Full article

Natural toothpastes were introduced to limit the use of chemical ingredients commonly found in conventional toothpastes. The purpose of this in vitro study was to evaluate the antimicrobial properties of three developed natural toothpastes containing different antimicrobial agents: (a) Biosecur Organic Oral Care (BOOC), (b) Microsilver BG, and (c) Cranberry LG. These toothpastes were compared with a natural toothpaste of the same composition but without any added natural antimicrobial agent (negative control), as well as with a commercial synthetic toothpaste (positive control). The antimicrobial properties of the toothpastes were assessed using the disc diffusion test against three oral pathogens: Candida albicans, Streptococcus mutans, and Prevotella intermedia. Each tested toothpaste sample was placed in Petri dishes, where specific microorganisms selected for the study were cultivated. After incubation, the circular area formed around the discs (diameter), known as the inhibition zone, was measured demonstrating the inhibitory effect of the product on the microorganisms used in the efficacy test. All the experimental toothpastes exhibited higher antimicrobial properties compared to the negative control group, except for Streptococcus mutans, where only BOOC-containing toothpaste presented significant higher inhibition zones (p < 0.001). Considering the outcomes of the antimicrobial property test, the most effective natural experimental toothpaste was the BOOC-containing one, which showed better antimicrobial behavior even from the commercially available synthetic toothpaste (positive control). The tested natural antimicrobial agents were effective for enhancing the antimicrobial properties of the experimental toothpastes that were included, especially Biosecur Organic Oral Care agent. Full article