Search Results (343)

Introduction: Carbapenem-resistant Klebsiella pneumoniae (CRKP) represents a critical public health threat due to its rapid nosocomial dissemination, limited therapeutic options, and elevated mortality rates. This study aimed to characterize the epidemiology, carbapenemase profiles, and antimicrobial susceptibility patterns of CRKP isolates, as well as the clinical features and outcomes observed in infected or colonized patients. Materials and Methods: We conducted a retrospective analysis of clinical and microbiological data from patients with CRKP infections or colonization admitted between January 2023 and January 2024. Descriptive statistics were used to assess prevalence, resistance patterns, and patient outcomes. Two binary logistic regression models were applied to identify independent predictors of sepsis and in-hospital mortality. Results: Among 89 CRKP isolates, 45 underwent carbapenemase typing. More than half were metallo-β-lactamase (MBL) producers, with 44.4% co-harbouring NDM and OXA-48-like enzymes. Surgical intervention was associated with a significantly lower risk of sepsis (p < 0.01) and in-hospital mortality (p = 0.045), whereas intensive care unit (ICU) stay was a strong predictor of both outcomes. ICU admission conferred a 10-fold higher risk of sepsis (95%Cl 2.4–41.0) and a 40.8-fold higher risk of in-hospital death (95% Cl 3.5–473.3). Limitations: This single-center retrospective study included a limited number of isolates in certain groups. Additionally, cefiderocol (FDC) susceptibility was assessed by disk diffusion rather than by the broth microdilution method. Conclusions: Our study underscores the increasing prevalence of metallo-beta-lactamase-producing CRKP, particularly strains harbouring dual carbapenemases. Timely recognition of high-risk patients, combined with the implementation of targeted infection control measures and the integration of novel therapeutic options, is crucial to optimize clinical management and reduce mortality associated with CRKP. Full article

Acinetobacter baumannii has emerged as a major pathogen responsible for healthcare-associated infections, particularly in intensive care units, contributing to significant morbidity and mortality due to its multidrug resistance and ability to persist in clinical environments. This study aimed to investigate the phenotypic and genomic characteristics of all multidrug-resistant A. baumannii isolates collected between January and June 2022 from two tertiary care hospitals in Thessaloniki, Greece. A total of 40 isolates were included. All isolates exhibited resistance to colistin; however, none harbored the mcr-1 to mcr-9 genes, as confirmed by polymerase chain reaction (PCR). PCR-based screening for virulence-associated genes revealed high prevalence rates of basD (100%), pld (95%), csuE (87.5%), and bap (77.5%). In contrast, ompA and pglC were not detected. Twitching motility ranged from 2 to 50 mm, with 25% of the isolates classified as non-motile and 20% as highly motile. Swarming motility was observed in all strains. Additionally, all isolates demonstrated positive α-hemolysis, suggesting a potential virulence mechanism involving tissue damage and iron acquisition. Pulsed-field gel electrophoresis (PFGE) revealed significant genomic diversity among the isolates, indicating a low likelihood of patient-to-patient or clonal transmission within the hospital setting. These findings highlight the complex relationship between antimicrobial resistance and virulence in clinical A. baumannii isolates and emphasize the urgent need for robust infection control strategies and continued microbiological surveillance. Full article

Background/Objectives: Increasing levels of antimicrobial resistance (AMR) have recently been observed at the human–domestic animal–wildlife interface. Wild birds have been identified as carriers of antimicrobial-resistant bacteria and serve as excellent biomarkers for epidemiological studies. This study assessed the current AMR presence in Eastern Spain’s commensal Escherichia coli isolated from free-ranging Bonelli’s eagles (Aquila fasciata). Methods: Nestlings and their nests were intensively sampled between 2022 and 2024 to determine their AMR profile and characterize E. coli. AMR testing was conducted using the broth microdilution method, following the European Committee on Antimicrobial Susceptibility Testing guidelines. Additionally, the presence of eaeA (intimin gene) and stx-1 and stx-2 (shiga toxins) was analyzed by real-time PCR to classify E. coli strains into enteropathogenic (EPEC) and Shiga-toxigenic (STEC) pathotypes. Results: Of all E. coli isolates, 41.7% were resistant to at least one antimicrobial, and 30% were multidrug-resistant. Only two strains were classified as EPEC and none as STEC. The highest resistance rates were observed for amoxicillin and tetracycline (19.6% each). Alarmingly, resistance to colistin and meropenem, last-resort antibiotics in human medicine, was also detected. Conclusions: Although the mechanisms of resistance acquisition remain unclear, transmission is likely to occur through the food chain, with synanthropic prey acting as intermediary vectors. These results highlight the role of Bonelli’s eagles as essential sentinels of environmental AMR dissemination, even in remote ecosystems. Strengthening One Health-based surveillance is necessary to address AMR’s ecological and public health risks in wildlife. Full article

Microbiological contamination of healthcare workers’ gowns represents a critical risk for the transmission of healthcare-associated infections (HAIs). Despite their use as protective equipment, gowns can act as reservoirs of antibiotic-resistant bacteria, favouring the spread of pathogens between healthcare workers and patients. The presence of these resistant bacteria on healthcare workers’ gowns highlights the urgent need to address this risk as part of infection control strategies. The aim of this work was to assess the microbiological risks associated with the contamination of healthcare staff gowns with Gram-negative bacteria, including the ESKAPE group, and their relationship with antimicrobial resistance. An observational, cross-sectional, prospective study was conducted in 321 hospital workers. The imprinting technique was used to quantify the bacterial load on the gowns, followed by bacterial identification by MALDI-TOF mass spectrometry. In addition, antimicrobial resistance profiles were analysed, and tests for carbapenemases and BLEE production were performed. The ERIC-PCR technique was also used for molecular analysis of Pantoea eucrina clones. Several Gram-negative bacteria were identified, including bacteria of the ESKAPE group. The rate of microbiological contamination of the gowns was 61.05% with no association with the sex of the healthcare personnel. It was observed that critical areas of the hospital, such as intensive care units and operating theatres, showed contamination by medically important bacteria. In addition, some strains of P. eucrina showed resistance to carbapenemics and cephalosporins. ERIC-PCR analysis of P. eucrina isolates showed genetic heterogeneity, indicating absence of clonal dissemination. Healthcare personnel gowns are a significant reservoir of pathogenic bacteria, especially in critical areas of Hospital Juárez de México. It is essential to implement infection control strategies that include improving the cleaning and laundering of gowns and ideally eliminating them from clothing to reduce the risk of transmission of nosocomial infections. Full article

Swine wastewater (SW) has a high chemical oxygen demand (COD) content and is difficult to degrade; an effective strategy to address this issue is through biodegradation, which poses negligible secondary pollution risks and ensures cost-efficiency. The objectives of this study were to isolate an effective COD-degrading strain of SW, characterize (at the molecular level) its transformation of SW, and apply it to practical production. A strain of Corynebacterium xerosis H1 was isolated and had a 27.93% ± 0.68% (mean ± SD) degradation rate of COD in SW. This strain precipitated growth in liquids, which has the advantage of not needing to be immobilized, unlike other wastewater-degrading bacteria. Based on analysis by Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), this bacterium removed nitrogen-containing compounds in SW, with proteins and lipids decreasing from 41 to 10% and lignins increasing from 51 to 82%. Furthermore, the enhancement of the sequencing batch reactor (SBR) with strain H1 improved COD removal in effluent, with reductions in the fluorescence intensity of aromatic protein I, aromatic protein II, humic-like acids, and fulvic acid regions. In addition, based on 16S rRNA gene sequencing analysis, SBR_H1 successfully colonized some H1 bacteria and had a higher abundance of functional microbiota than SBR_C. This study confirms that Corynebacterium xerosis H1, as a carrier-free efficient strain, can be directly applied to swine wastewater treatment, reducing carrier costs and the risk of secondary pollution. The discovery of this strain enriches the microbial resource pool for SW COD degradation and provides a new scheme with both economic and environmental friendliness for large-scale treatment. Full article

The extensive use of copper in thermal and electrical systems calls for constant performance enhancement by means of innovative material treatments. The effects on the microstructural, mechanical, and electrical characteristics of copper in deep cryogenic treatment (DCT) and deep cryogenic treatment followed by heat treatment (DCT + HT) are investigated in this work. Copper samples were treated for various soaking durations ranging from 6 to 24 h. Mechanical properties such as tensile strength, hardness, and wear rate were analyzed. In the DCT-treated samples, tensile strength increased, reaching a peak of 343 MPa at 18 h, alongside increased hardness (128 HV) and a refined grain size of 9.58 µm, primarily due to elevated dislocation density and microstrain. At 18 h of soaking, DCT + HT resulted in improved structural stability, high hardness (149 HV), a fine grain size (7.42 µm), and the lowest wear rate (7.73 × 10⁻¹⁰ mm³/Nm), consistent with Hall–Petch strengthening. Electrical measurements revealed improved electron mobility (52.08 cm²/V·s) for samples soaked for 24 h in DCT + HT, attributed to increased crystallite size (39.9 nm), reduced lattice strain, and higher (111) texture intensity. SEM–EBSD analysis showed a substantial increase in low-angle grain boundaries (LAGBs) in DCT + HT-treated samples, correlating with enhanced electrical conductivity. Overall, an 18 h soaking duration was found to be optimal for both treatments. However, the strengthening mechanism in DCT + HT is influenced by grain boundary stabilization and thermal recovery and is different to DCT, which is strain-induced enhancement. Full article

Salinity serves as a critical environmental factor influencing the physiological and morphological characteristics of Spirulina, a filamentous cyanobacterium used for food production and commercial purposes. This study examined a Spirulina strain’s responses to different salinity levels (10–45 ppt) through three independent laboratory experiments that determined growth, productivity, and size structure. Growth across salinity treatments was assessed by monitoring optical density in 24-well microplates over 20 days and estimating specific growth rates using a logistic growth model. Primary productivity under different salinity and light conditions was measured using light and dark bottle experiments to calculate gross primary productivity (GPP) and to estimate photosynthetic efficiency through linear regression of GPP against light intensity. The size structure was assessed through tube-based experiments and image analysis, with organism sizes categorized and analyzed to identify salinity-induced patterns in filament structure. The study demonstrated that the Spirulina strain achieved its greatest growth at 10 ppt yet produced the highest photosynthetic efficiency between 27 and 45 ppt because it reallocated energy during salinity stress. The morphological analysis revealed that the Spirulina strain produced medium-sized filaments between 400 and 799 µm at elevated salinity levels, and our analysis confirmed substantial variations in size structure. The Spirulina strain demonstrates both physiological and morphological plasticity when exposed to salinity changes. The cultivation of the Spirulina strain at 27 ppt provides conditions that support moderate growth, enhanced productivity, and manageable morphological shifts while using its natural salinity tolerance to improve the efficiency and scalability of production for diverse biotechnological applications. Full article

The global rise of carbapenem-resistant Acinetobacter baumannii (CRAB) strains poses a critical challenge to healthcare systems due to limited therapeutic options and high mortality rates, especially in intensive care settings. This review explores the epidemiological landscape and molecular mechanisms driving carbapenem resistance, including the production of diverse beta-lactamases (particularly OXA-type enzymes), porin loss, efflux pump overexpression, and mutations in antibiotic targets. Emerging treatment strategies are discussed, such as the use of new beta-lactam–beta-lactamase inhibitor combinations (e.g., sulbactam–durlobactam), siderophore cephalosporins, next-generation polymyxins, as well as novel agents like zosurabalpin and rifabutin (BV100). Alternative approaches—including phage therapy, antimicrobial peptides, CRISPR-based gene editing, and nanoparticle-based delivery systems—are also evaluated for their potential to bypass traditional resistance mechanisms. Furthermore, advances in artificial intelligence and multi-omics integration are highlighted as tools for identifying novel drug targets and predicting resistance profiles. Together, these innovations represent a multifaceted strategy to overcome CRAB infections, yet their successful implementation requires further clinical validation and coordinated surveillance efforts. This analysis highlights the urgent need for continued investment in innovative treatments and effective resistance monitoring to limit the spread of CRAB and protect the effectiveness of last-line antibiotics. Full article

Microcystis aeruginosa is a cyanobacterium frequently associated with toxic blooms in eutrophic freshwater systems. Certain strains produce microcystins (MCs), a group of hepatotoxins with significant ecological and public health implications. In this study, we examined the quantitative response of a temperate native M. aeruginosa strain to combinations of temperature (26, 30, and 36 °C), light intensity (30, 50, and 70 µmol photons·m⁻²·s⁻¹), and N:P ratio (10, 100, 150), using a full-factorial experimental design. Growth parameters (µ, lag phase duration, and maximum cell density), chlorophyll-a production, and MC-LR synthesis were modeled using Gompertz, linear, and dynamic approaches. High temperature and irradiance increased the specific growth rate but decreased final biomass, while elevated N:P ratios shortened the lag phase. MC-LR production peaked under low temperature, low irradiance, and low N:P ratio. Although MC-LR synthesis did not correlate positively with growth rate, and the environmental conditions maximizing growth differed from those enhancing toxin production, a population-level coupling between both processes was observed using the Long model. These findings suggest that MC-LR synthesis in M. aeruginosa is not merely a metabolic by-product of growth, but a context-dependent trait with potential adaptive significance. Full article

This study systematically investigated two ecotypes of Ulva prolifera, the dominant species responsible for green tides in the Yellow Sea, classified as Subtype I (strain I08-1) and Subtype II (strain QD-7). Both subtypes produce positively phototactic biflagellate gametes with oval/pear-shaped morphology but exhibit distinct cellular dimensions. Subtype I gametes demonstrated significantly larger cell sizes, with long and short axes measuring 6.55 μm and 4.62 μm, respectively, compared to Subtype II’s dimensions of 6.46 μm (long axis) and 3.03 μm (short axis). Developmental analysis revealed striking morphological divergence at the 6-day germling stage: Subtype I attained an average length of 1301.14 μm, more than doubling Subtype II’s 562.25 μm. Superior growth kinetics were observed in Subtype I, exhibiting enhanced specific growth rates (SGRs) across multiple parameters—main stem length (8.58% vs. 3.55%), primary branch elongation (19.17% vs. 12.59%), main stem width expansion (17.29% vs. 5.00%), and biomass accumulation (41.90% vs. 40.96% fresh weight). Chlorophyll quantification confirmed significantly higher pigment content in Subtype I. Pre-co-culture photosynthetic profiling demonstrated Subtype I’s superior quantum efficiency (α = 0.077 vs. 0.045) with marked differences in regulated energy dissipation (YNPQ) and non-photochemical quenching (NPQ). Post-co-culture physiological adaptation was evident in Subtype II, showing significant elevation of non-regulated energy dissipation quantum yield (YNO) and eventual surpassing of maximum electron transport rate (ETRmax) compared to Subtype I. These findings establish that U. prolifera employs robust photoprotective and thermal adaptation strategies under natural photothermal conditions. Crucially, YNO-based analysis revealed Subtype II’s enhanced high-light protection mechanisms and superior adaptability to intense irradiance environments. This research elucidates ecotype-specific environmental adaptation mechanisms in U. prolifera, providing critical insights for optimizing green tide mitigation strategies and advancing ecological understanding of algal bloom dynamics. Full article

In the field of crack mechanics, predicting the direction of a crack is important because this will evaluate whether, when the crack propagates, it penetrates into important areas and whether the structure is dangerous or not. This paper will refer to three theories that predict the propagation direction of cracks: a theory of maximum tangential normal stress, a theory of maximum energy release, and a theory of minimum strain energy density. At the same time, the finite element method (FEM)–ANSYS program will be used to calculate stress intensity factors (SIFs), strain energy release rate (J-integral), stress field, displacement near a crack tip, and crack propagation phenomenon based on the above theories. The calculated results were compared with the results in other scientific papers and experimental results. This research used ANSYS program, an experimental method combined with FEM based on the above energy theories to simulate the J-integral, the SIFs, and the crack propagation. The errors of the SIFs of the FGM rectangular plate has a through-thickness center crack of 1.77%, J-integral of 4.49%, and crack propagation angle ${\theta }_c$ of 0.15%. The FEM gave good errors compared to experimental and exact methods. Full article

Modern requirements for aluminum alloys used in mechanical engineering and aviation include increased strength characteristics and refined microstructure. One of the promising methods for improving the properties of aluminum alloys is rolling on a three-high skew rolling mill, which provides intense plastic deformation and a fine-grained structure. This study describes the results of numerical modeling of the rolling process of aluminum alloy 6082 rods in a three-high skew-type mill. Numerical modeling of alloy 6082 was conducted using the ForgeNxT 2.1 software designed to simulate metal-forming processes, including rolling. The rheological behavior of the material under study was investigated by compression tests using a Gleeble 3800 plastometer (“DSI”, Austin, TX, USA), which enabled the determination of the main parameters of material flow under specified conditions. The process of rolling bars of alloy 6082 on a three-high skew mill was numerically analyzed in the temperature range of 350–400 °C. This allowed for the study of the distribution of stresses, temperatures, and strain rates from the rolling mode. A physical experiment was conducted to validate the results of numerical modeling. The obtained results enabled the identification of rolling modes that promote microstructure refinement and enhance the mechanical properties of the alloy. Full article

To investigate the effects of the strain rate and confinement on characteristic stresses and strength criterion in granite under static to quasi-static loading, triaxial compression tests were systematically conducted across strain rates of 10⁻⁶ to 10⁻² s⁻¹ and confining pressures of 0–40 MPa. Stress–strain curves, characteristic stresses, macro-fracture patterns, and dynamic strength criterion were analyzed. The experimental results indicate the following: (1) crack damage stress (σ_cd) and peak stress (σ_p) show strong linear correlations with logarithmic strain rate, while crack initiation stress (σ_ci) exhibits weaker rate dependence; (2) linear regression establishes characteristic stress ratios σ_ci = 0.58σ_p and σ_cd = 0.85σ_p; (3) macroscopic fractures transition from Y-shaped shear patterns under low confinement and strain rate conditions to X-shaped shear failures at higher confinement and strain rate; (4) the Mohr–Coulomb criterion effectively characterizes dynamic strength evolution in granite, with cohesion increasing 22% across tested strain rates while internal friction angle remains stable at around 50°; (5) variations in microcrack activity intensity during rock deformation stages result in the dynamic increase factor for characteristic stresses (CSDIF) of σ_ci being lower than σ_cd and σ_p. More importantly, σ_cd and σ_p exhibit CSDIF reductions as confining pressure increases. This differential behavior is explained by confinement-enhanced shear fracturing dominance during crack propagation stages, combined with the lower strain rate sensitivity of shear versus tensile fracture toughness. Full article

Background/Objectives: Beetroot juice (BJ), a natural source of dietary nitrate, has gained increasing attention for its potential to improve exercise performance and cardiovascular function. While its benefits are well documented in endurance contexts, less is known about its short-term effects on resistance training performance and recovery. Thus, this study investigated the effects of short-term BJ supplementation on strength performance, cardiovascular responses, muscle oxygenation, and post-exercise recovery in resistance-trained males. Methods: Twelve healthy men (age: 21.3 ± 1.9 years; body mass index: 21.42 ± 2.36 kg/m²) completed two supplementation protocols involving BJ, providing 450 mg of nitrate per day, and a nitrate-free placebo (PLA). Each protocol consisted of two laboratory visits, one to assess the acute ergogenic effects and another to evaluate recovery after 72 h, resulting in a total of four sessions over a two-week period. During the three consecutive days of supplementation, participants ingested a single 900 mL dose (15 g BJ powder/PLA) 2 h before the first session, followed by three daily 300 mL doses (5 g BJ each/PLA) over the next two days, and a final dose (15 g BJ powder/PLA) taken 2 h before the second session (72 h post-first session). Each testing session involved incremental back squat (BS) and bench press (BP) exercises at 60%, 70%, and 80% of the one-repetition maximum (1RM) performed to failure, with three-minute rest intervals between sets. Repetition to failure, movement velocity, peak power, peak heart rate (HR), and muscle oxygenation (SmO₂) were recorded during BP and BS exercises. Heart rate variability (HRV) and blood lactate were assessed before and after each training session. Lower-limb strength (CMJ and SJ) and delayed-onset muscle soreness (DOMS) were assessed daily during the 3-day supplementation period. Results: BJ significantly increased repetitions completed at 80% 1RM during BP and BS (p < 0.05) compared to the PLA. Peak movement velocity improved across all intensities using BJ with higher values compared to the PLA at 60–80% 1RM (p < 0.05). SmO₂ was higher in BJ at 70–80% 1RM) and further improved after 72 h of BJ supplementation (p < 0.05). Cardiovascular strain was reduced in BJ, evidenced by lower peak HRs and smaller post-exercise declines in HRV indices (p < 0.05). Post-exercise recovery favored BJ, with faster recovery in jump performance at 24 h and reduced upper-limb DOMS at 24–48 h (p < 0.05). Conclusions: Short-term BJ supplementation enhances high-intensity resistance performance, improves muscle oxygenation, attenuates cardiovascular strain, and accelerates neuromuscular recovery. These benefits highlight its potential as a practical strategy for athletes seeking to optimize training performance and recovery during periods of intense resistance training. Full article

Eye diseases (EDs), including glaucoma, diabetic retinopathy, and cataracts, are major contributors to vision loss and reduced quality of life worldwide. These conditions not only affect millions of individuals but also impose a significant burden on global healthcare systems. As the population ages and lifestyle changes increase the prevalence of conditions like diabetes, the incidence of EDs is expected to rise, further straining diagnostic and treatment resources. Timely and accurate diagnosis is critical for effective management and prevention of vision loss, as early intervention can significantly slow disease progression and improve patient outcomes. However, traditional diagnostic methods rely heavily on manual analysis of fundus imaging, which is labor-intensive, time-consuming, and subject to human error. This underscores the urgent need for automated, efficient, and accurate diagnostic systems that can handle the growing demand while maintaining high diagnostic standards. Current approaches, while advancing, still face challenges such as inefficiency, susceptibility to errors, and limited ability to detect subtle retinal asymmetries, which are critical early indicators of disease. Effective solutions must address these issues while ensuring high accuracy, interpretability, and scalability. This research introduces a 2D single-channel convolutional neural network (CNN) based on ResNet101-V2 architecture. The model integrates gradient-weighted class activation mapping (Grad-CAM) to highlight retinal asymmetries linked to EDs, thereby enhancing interpretability and detection precision. Evaluated on retinal Optical Coherence Tomography (OCT) datasets for multiclass classification tasks, the model demonstrated exceptional performance, achieving accuracy rates of 99.90% for four-class tasks and 99.27% for eight-class tasks. By leveraging patterns of retinal symmetry and asymmetry, the proposed model improves early detection and simplifies the diagnostic workflow, offering a promising advancement in the field of automated eye disease diagnosis. Full article