Search Results (82)

Aeromonas salmonicida is a major pathogen in aquaculture, and its ability to form biofilms contributes significantly to antibiotic resistance and chronic infections. This study investigated the effects of four antibiotics—ampicillin, amoxicillin, oxytetracycline, and doxycycline—at various concentrations on bacterial growth, biofilm formation, and gene expression related to antibiotic resistance and quorum sensing (QS) in two subspecies: A. salmonicida subsp. masoucida (ASM) and A. salmonicida subsp. salmonicida (ASS). Bacterial isolates from Atlantic salmon were identified using 16S rRNA and vapA gene sequencing. Growth inhibition was more pronounced in ASS than ASM under high antibiotic concentrations. Conversely, sub-inhibitory concentrations (sub-MICs) enhanced biofilm formation in both subspecies, particularly in ASM. PCR results showed that tetA and tetE resistance genes were present only in ASM. qRT-PCR analysis revealed that expression of QS-related genes (ahyI and ahyR) was generally downregulated under tetracycline treatment, while litR expression varied across antibiotic conditions and strains. Some isolates showed increased litR expression alongside elevated biofilm formation, suggesting involvement of additional regulatory mechanisms. These results highlight the potential for sub-MIC antibiotic exposure to promote biofilm development and modulate gene expression, emphasizing the need for careful antibiotic use in aquaculture and providing insight into alternative pathogen control strategies. Full article

The pilot flame serves as the primary anchor for global flame stabilization in a centrally staged combustor. In engineering practice, it typically operates in the diffusion mode. The fuel non-uniformity and diffusion kinetics of the pilot flame may have a significant impact on the flow and flames within the combustor. The flame structure and flame–flow interaction in a centrally staged burner featuring a diffusion pilot flame are investigated in the present paper, using high-frequency CH₂O planar laser-induced fluorescence (CH₂O-PLIF), CH^* chemiluminescence, and particle image velocimetry (PIV) measurements. The stratified flame (S-flame) and the lifted flame (L-flame) are identified under two-stage conditions. The S-flame and L-flame correspond to the separated flow and the merged flow of the two stages, respectively. Significant radial oscillation of the pilot stage airflow is also found. Extensive tests demonstrate that the pilot equivalence ratio (Φp) plays an important role in flame mode switching. Silicone droplets with extremely fine sizes are introduced into the pilot fuel to trace its transportation. When the oscillating pilot stage airflow rushes towards the lip in an instant, it can entrain the pilot fuel to reach the inner side of the main stage outlet. With a low pilot fuel supply and relatively low injection velocity, the pilot fuel and the hot radicals are more likely to be entrained and accumulate in larger amounts at the inner side of the main stage outlet. Consequently, the main stage premixed mixture can be ignited at the main stage outlet, forming the S-flame. The flame mode switches from S- to L-flame when the equivalence ratio increases to the point where the corresponding velocity ratio of pilot fuel to air (V_fp/V_ap) approaches 1.0, with a reduced entrainment of the pilot fuel and radicals. Simultaneous CH₂O-PLIF and flow field results show that when the main stage is ignited downstream, hot products cannot recirculate to the pilot stage outlet, causing the extinction of the pilot flame root. This paper reveals that the fuel diffusion characteristics of the pilot stage can dramatically change the flame structure. To achieve the ideal designed flame shape, the interaction between the pilot fuel and pilot air requires very careful treatment in practical centrally staged combustors. Full article

Ventilator-associated pneumonia (VAP) is one of the most common hospital-acquired infections. Several studies have explored the potential role of the lung microbiome as a biomarker for identifying and predicting the prognosis of VAP. However, research on the respiratory microbiome in individuals with VAP caused by carbapenem-resistant Acinetobacter baumannii (CRAB) remains limited. Therefore, we aimed to analyze the respiratory microbiome of patients with CRAB VAP. Respiratory specimens were collected from patients who developed CRAB VAP. Microbiome diversity and composition were analyzed using 16S rRNA gene pyrosequencing. Patients were categorized into two groups based on mortality outcomes: intensive care unit (ICU) mortality or 28-day mortality after ICU discharge. Twenty patients with CRAB VAP were enrolled, including nine in the mortality group. No significant differences were observed in α-diversity indices between the study groups. However, multivariable Firth’s logistic regression revealed a significant association between a relative abundance of the Enterococcus genus ≥ 1% and mortality outcomes (odds ratio: 0.06; 95% confidence interval: 0.00–0.771; p = 0.029). This study characterized the respiratory microbiome of patients with CRAB VAP and highlighted the potential role of microbiome analysis in predicting disease prognosis. Further studies with larger sample sizes are warranted to validate these findings. Full article

Background/Objectives: Lower respiratory tract infections (LRTIs) are frequent in the intensive care unit (ICU) and drive empiric broad-spectrum antibiotic use. Rapid multiplex PCR assays may improve pathogen detection and stewardship compared with conventional culture. We evaluated the real-world impact of the BioFire^® FilmArray^® Pneumonia Panel Plus (FA-PNEU^®) on antimicrobial management in suspected nosocomial LRTI. Methods: This was a single-centre, prospective observational cohort study conducted in a tertiary ICU (Madrid, Spain) between April 2021 and March 2025. Adult patients with suspected hospital-acquired pneumonia (HAP), ventilator-associated pneumonia (VAP), or ventilator-associated tracheobronchitis (VAT) were included if paired respiratory samples underwent FA-PNEU^® and conventional culture (CC). Diagnostic accuracy and prescribing changes were analysed. Results: A total of 344 samples from 236 patients were included. FA-PNEU^® demonstrated high sensitivity (93.4%) and negative predictive value (97.9%) but moderate specificity (65.0%) and low positive predictive value (36.5%). False positives occurred in 85.8% of patients with prior antibiotic therapy targeting the detected organism. Antibiotic management was considered directly influenced by FA-PNEU^® when any prescribing decision (initiation, escalation, de-escalation, or discontinuation) explicitly followed the panel’s results rather than other clinical or microbiological information. Using this definition, FA-PNEU^® directly influenced antibiotic therapy in 57.6% of cases, while in 17.7%, prescribing was instead guided by a suspected alternative infection. In patients without prior antibiotics, treatment initiation or withholding was fully concordant with FA-PNEU^® results, while in those already receiving therapy, 60.8% underwent modification, two-thirds in agreement with the panel. Conclusions: In critically ill patients with suspected nosocomial LRTI, FA-PNEU^® provided rapid, high-sensitivity diagnostics that substantially influenced antimicrobial prescribing. Its greatest value lies in ruling out bacterial infection and guiding stewardship, though results must be interpreted within the full clinical and microbiological context. Full article

Lower respiratory tract infections (LRTIs) remain a major cause of global morbidity and mortality, yet accurate pathogen identification and risk stratification continue to pose clinical challenges. Lipidomics—the comprehensive analysis of lipid species within biological systems—has emerged as a promising tool to unravel host–pathogen interactions and reveal novel diagnostic and prognostic biomarkers. This systematic review synthesizes evidence from nine original studies applying mass spectrometry-based lipidomic profiling in human LRTIs, including community-acquired pneumonia (CAP), ventilator-associated pneumonia (VAP), and coronavirus disease 2019 (COVID-19). Across diverse study designs, sample types, and analytical platforms, consistent alterations in lipid metabolism were observed. Perturbations in phospholipid classes, particularly phosphatidylcholines (PCs) and lysophosphatidylcholines (LPCs), were frequently associated with disease severity and immune activation. The ratios of PC to LPC and phosphatidylethanolamine (PE) to lysophosphatidylethanolamine (LPE) emerged as markers of inflammatory remodeling. Sphingolipids—including sphingomyelins (SMs) and sphingosine-1-phosphate (S1P)—were identified as key modulators of monocyte and neutrophil activation. Fatty acid–derived lipid mediators such as oxylipins (e.g., 12,13-epoxyoctadecenoic acid and 15-hydroxyeicosatetraenoic acid) and acylcarnitines reflected pathogen-specific immune responses and mitochondrial dysfunction. Several lipid-based classifiers demonstrated superior diagnostic and prognostic performance compared to conventional clinical scores, including the CURB-65 and pneumonia severity index. However, significant heterogeneity in experimental design, lipid identification workflows, and reporting standards limits inter-study comparability. While preliminary findings support the integration of lipidomics into infectious disease research, larger multi-omic and longitudinal studies are required. This review provides the first comprehensive synthesis of lipidomic alterations in human LRTIs and highlights their emerging translational relevance. Full article

Background: Accurate differentiation of Parkinson’s disease (PD) from healthy aging is crucial for timely intervention and effective management. Postural sway abnormalities are prominent motor features of PD. Quantitative stabilometry and machine learning (ML) offer a promising avenue for developing objective markers to support the diagnostic process. This study aimed to develop and validate high-performance ML models to classify individuals with PD and age-matched healthy older adults (HOAs) using a comprehensive set of stabilometric parameters. Methods: Thirty-seven HOAs (mean age 70 ± 6.8 years) and 26 individuals with idiopathic PD (Hoehn and Yahr stages 2–3, on medication; mean age 66 years ± 2.9 years), all aged 60–80 years, participated. Stabilometric data were collected using a force platform during quiet stance under eyes-open (EO) and eyes-closed (EC) conditions, from which 34 parameters reflecting the time- and frequency-domain characteristics of center-of-pressure (COP) sway were extracted. After data preprocessing, including mean imputation for missing values and feature scaling, three ML classifiers (Random Forest, Gradient Boosting, and Support Vector Machine) were hyperparameter-tuned using GridSearchCV with three-fold cross-validation. An ensemble voting classifier (soft voting) was constructed from these tuned models. Model performance was rigorously evaluated using 15 iterations of stratified train–test splits (70% train and 30% test) and an additional bootstrap procedure of 1000 iterations to derive reliable 95% confidence intervals (CIs). Results: Our optimized ensemble voting classifier achieved excellent discriminative power, distinguishing PD from HOAs with a mean accuracy of 0.91 (95% CI: 0.81–1.00) and a mean Area Under the ROC Curve (AUC ROC) of 0.97 (95% CI: 0.92–1.00). Importantly, feature analysis revealed that anteroposterior sway velocity with eyes open (V-AP) and total sway path with eyes closed (TOD_EC, calculated using COP displacement vectors from its mean position) are the most robust and non-invasive biomarkers for differentiating the groups. Conclusions: An ensemble ML approach leveraging stabilometric features provides a highly accurate, non-invasive method to distinguish PD from healthy aging and may augment clinical assessment and monitoring. Full article

The Helicobacter pylori vapD gene is transcribed and expressed when the bacteria are within the gastric cell. In this current study, we investigated how vapD knockout affects the survival of H. pylori inside human gastric adenocarcinoma cells. We constructed an H. pylori 26695 vapD (Hp ΔvapD) mutant strain. H. pylori 26695 wt and Hp ΔvapD strains were grown in synthetic media and were co-cultured with AGS cells. From the start, the growth curve, total protein concentration and colony-forming units (CFUs) of each strain were measured. From each co-culture, CFUs and total RNA were obtained, and transcript levels of GAPDH, vapD, vacA, ureA, and 16s Hp were measured by qRT-PCR. Hp ΔvapD did not affect the growth rate of the strain in synthetic media, showing that the vapD gene is not necessary when the bacteria grow outside eukaryote cells. However, in the intracellular environment, the number of CFUs recovered from the Hp ΔvapD strain from AGS cells decreased after 36 h. Transcription levels of the vacA gene from the Hp ΔvapD strain were 10,000-fold lower than those of H. pylori wt, to the point of being undetectable. The results suggest that the vapD gene contributed to maintaining H. pylori inside gastric cells. Full article

Ventilator-associated pneumonia (VAP) develops in patients who stay on mechanical ventilation for more than 48 h. In the presence of causative pathogens, the patient develops clinical signs such as purulent tracheal discharge, fever, and respiratory distress. A prospective observational study was carried out in the Intensive Care Unit (ICU) of Max Healthcare Centre, New Delhi, from 2020 to 2023. The study comprised 70 samples from patients diagnosed with VAP. This study thoroughly examined VAP-associated microorganisms and resistance in the hospital ICU. Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa were the most commonly reported pathogens. Significant drug resistance was seen in P. aeruginosa, K. pneumoniae, A. baumannii and Staphylococcus aureus. The heatmap also supported the antibiotic resistance data patterns obtained from conventional and automated systems of determination. Notably, Serratia marcescens, Escherichia coli, Klebsiella pneumoniae, Ralstonia insidiosa, and Ralstonia mannitolilytica, showed 60 to 100% of resistance to a number of antibiotics. Among all VAP patients, 31.42% early-onset and 68.57% late-onset VAP cases were detected. Out of 70 patients, 43 patients died (mortality rate 61.4%); majority of them suffered from late-onset VAP. The study goal was to describe the antibiotic resistance patterns and microbial ecology of the pathogens that were isolated from VAP patients. According to the heatmap analysis, a varied VAP microbiome with high prevalences of MDR in A. baumannii, P. aeruginosa, K. pneumoniae, and S. aureus was identified. To address the increasing prevalence of MDR VAP, the study highlights the critical need for improved VAP monitoring, strong infection control, and appropriate antibiotic usage. Full article

The physiological functions of mammalian sperm, such as motility, hyperactivation, and capacitation, require substantial energy. This study investigates the effects of two classic cryopreservation extenders—TCG (tris-citrate-glucose) and LEY (lactose-egg yolk)—on the energy metabolism of frozen–thawed boar semen. By comparing the quality indicators, key metabolite levels, and the activities of critical enzymes involved in glycolysis and the tricarboxylic acid cycle, we aim to understand how these different semen extenders influence the spermatozoa vitality of frozen–thawed boar semen. Following thawing, the LEY-cryopreserved sperm demonstrated significantly elevated motility parameters (viability, VCL, VSL, and VAP) and enhanced plasma membrane and acrosomal integrity compared with the TCG group (p < 0.05), though both cryopreserved groups exhibited significantly reduced performance relative to fresh semen controls. Cryopreservation markedly reduced intracellular adenosine triphosphate (ATP), pyruvate, and acetyl coenzyme A (A-CoA) levels (fresh > LEY > TCG; p < 0.05). The LEY-preserved spermatozoa retained higher activities of glycolysis-related enzymes (phosphofructokinase, PFK; pyruvate kinase, PK) compared with the TCG group, which, in turn, showed elevated lactate dehydrogenase (LDH) activity. Critically, TCG-suppressed pyruvate dehydrogenase (PDH) activity (p < 0.05) coincided with diminished A-CoA, indicating impaired mitochondrial oxidative phosphorylation. These results demonstrate LEY’s superior preservation of motility and membrane stability but highlight cryodamage-induced energy metabolism dysregulation, particularly TCG’s disruption of the glycolysis–TCA cycle coordination essential for spermatozoa function. In conclusion, the choice of semen extender has a significant impact on the energy metabolism and overall quality of frozen–thawed semen, highlighting the importance of optimizing cryopreservation protocols for improved spermatozoa viability and functionality. Full article

Background: Ventilator-associated pneumonia (VAP) is a common and serious ICU complication, affecting up to 40% of mechanically ventilated patients. The diagnosis of VAP currently relies on retrospective clinical, radiological, and microbiological criteria, which often delays targeted treatment and promotes the overuse of broad-spectrum antibiotics. The early prediction of VAP is crucial to improve outcomes and guide antimicrobial use related to this disease. This study aimed to develop and validate PREDICT (Pneumonia Risk Evaluation and Diagnostic Intelligence via Computational Technology), a deep learning algorithm for early VAP prediction that is based solely on vital signs. Methods: We conducted a retrospective cohort study using the MIMIC-IV database, which includes ICU patients who were ventilated for at least 48 h. Five vital signs (respiratory rate, SpO₂, heart rate, temperature, and mean arterial pressure) were structured into 24 h temporal windows. The PREDICT model, based on a long short-term memory neural network, was trained to predict the onset of VAP 6, 12, and 24 h in the future. Its performance was compared to that of conventional machine learning models (random forest, XGBoost, logistic regression) using their AUPRC, sensitivity, specificity, and predictive values. Results: PREDICT achieved high predictive accuracy with AUPRC values of 96.0%, 94.1%, and 94.7% at 6, 12, and 24 h before the onset of VAP, respectively. Its sensitivity and positive predictive values exceeded 85% across all horizons. Traditional ML models showed a drop in performance over longer timeframes. Analysis of the model’s explainability highlighted the respiratory rate, SpO₂, and temperature as key predictive features. Conclusions: PREDICT is the first deep learning model specifically designed for early VAP prediction in ICUs. It represents a promising tool for timely clinical decision-making and improved antibiotic stewardship. Full article

Constructing visually appealing public spaces has become an important issue in contemporary urban renewal and design. Existing studies mostly focus on single dimensions (e.g., vegetation ratio), lacking a large-scale integrated analysis of urban color and visual elements. To address this gap, this study employs semantic segmentation and color computation on a massive street-view image dataset encompassing 56 cities worldwide, comparing eight machine learning models in predicting Visual Aesthetic Perception Scores (VAPSs). The results indicate that LightGBM achieves the best overall performance. To unpack this “black-box” prediction, we adopt an interpretable ensemble approach by combining LightGBM with Shapley Additive Explanations (SHAPs). SHAP assigns each feature a quantitative contribution to the model’s output, enabling transparent, post hoc explanations of how individual color metrics and visual elements drive VAPS. Our findings suggest that the vegetation ratio contributes the most to VAPS, but once greening surpasses a certain threshold, a “saturation effect” emerges and can no longer continuously enhance visual appeal. Excessive Sky Visibility Ratio can reduce VAPS. Moderate road visibility may increase spatial layering and vibrancy, whereas overly dense building significantly degrades overall aesthetic quality. While keeping the dominant color focused, moderate color saturation and complexity can increase the attractiveness of street views more effectively than overly uniform color schemes. Our research not only offers a comprehensve quantitative basis for urban visual aesthetics, but also underscores the importance of balancing color composition and visual elements, offering practical recommendations for public space planning, design, and color configuration. Full article

Despite the increased reporting of Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKp) in Egypt, there is a paucity of information regarding the molecular characteristics of such strains. Herein, we present the genome sequence of two CR-hvKp strains, K22 and K45, which were isolated from VAP (ventilator-associated-pneumonia) patients admitted to pediatric ICU at Assiut University Children’s Hospital, Egypt. K22 and K45 isolates were subjected to antimicrobial susceptibility testing and whole-genome sequencing. Genomic analysis was performed to characterize each strain, determining their plasmids, antimicrobial resistance (AMR) genes, and virulence determinants. K22 possessed an extensive drug resistance phenotype (XDR), whilst K45 exhibited a multidrug resistance phenotype (MDR), with genome sequencing revealing the presence of a diverse array of AMR genes. Both strains were resistant to the carbapenem antibiotic imipenem, carrying the OXA-48 carbapenemase, with K22 additionally possessing an NDM-1 carbapenemase. Each strain was considered high-risk, with K22 and K45 respectively belonging to sequence types ST383 and ST14 and possessing virulence genes implicated in hypervirulence (e.g., iucABCD-iutA and rmpA). Importantly, both strains carried multiple plasmid replicons, including an AMR/virulence IncHI1B/FIB hybrid plasmid and MDR IncL/M plasmids. This report highlights the critical role of plasmids in the evolution of virulent K. pneumoniae strains and suggests the circulation of an IncHI1B/FIB hybrid plasmid, simultaneously disseminating AMR and hypervirulence, amongst K. pneumoniae strains within Assiut University Children’s Hospital. Full article

(1) Background: To explore the anti-obesity effects and mechanisms of sika deer velvet antler peptides (sVAP) on 3T3-L1 preadipocytes and in high-fat diet (HFD)-induced obese mice. (2) Methods: sVAP fractions of different molecular weights were obtained via enzymatic hydrolysis and ultrafiltration. Their anti-lipid effects on 3T3-L1 cells were assessed with Oil Red O staining. The optimal fraction was tested in HFD-induced obese C57BL/6 mice to explore anti-obesity mechanisms. Peptide purification used LC-MS/MS, followed by sequence analysis and molecular docking for activity prediction. (3) Results: The peptide with the best anti-obesity activity was identified as sVAP-3K (≤3 kDa). sVAP-3K reduced lipid content and proliferation in 3T3-L1 cells, improved lipid profiles and ameliorated adipocyte degeneration in HFD mice, promoted the growth of beneficial gut microbiota, and maintained lipid metabolism. Additionally, sVAP-3K activated the AMP-activated protein kinase (AMPK) signaling pathway, regulating adipogenic transcription factors. sVAP-3K exhibited ten major components (peak area ≥ 1.03 × 10⁸), with four of the most active components being newly discovered natural oligopeptides: RVDPVNFKL (m/z 363.21371), GGEFTPVLQ (m/z 474.24643), VDPENFRL (m/z 495.25735), and VDPVNFK (m/z 818.44043). (4) Conclusion: This study identifies four novel oligopeptides in sVAP-3K as key components for anti-obesity effects, offering new evidence for developing natural weight-loss drugs from sika deer velvet. Full article

Aeromonas salmonicida is a predominant pathogen that infects fish. The pathogen A. salmonicida subsp. masoucida (ASM) was isolated for the first time from diseased starry flounders (Platichthys stellatus). Our study aimed to isolate, characterize, and investigate the pathogenicity of ASM. Bacterial species were identified using 16s rRNA, gyrB, dnaJ, and vapA analyses. Phylogenetic tree analysis revealed that the ASM strains were clustered with the ASM ATCC strain and other strains isolated from black rockfish. In the antimicrobial susceptibility test, the three ASM strains were considered non-wild types for enrofloxacin, florfenicol, flumequine, oxolinic acid, and oxytetracycline susceptibility. Histopathological analysis revealed bacterial colonies in the secondary lamella and heart, indicating that ASM strains are highly virulent in fish. Comparative analysis and annotation via genome sequencing revealed that, among the 1156 factors, adherence factors were the most prevalent putative virulence determinants, followed by the effector delivery system and adherence. ASM was found to possess 43 type III secretion systems, 22 type VI secretion systems, 11 antimicrobial resistance genes, 3 stress genes, and prophage regions. These findings provide new insights into the virulence profile of ASM and highlight the risk posed by emerging pathogenic strains to starry flounders. Full article

Background/Objectives: Ventilator-associated pneumonia (VAP) is the main nosocomial infection in intensive care units (ICUs) that causes the highest morbidity and mortality. The aim of our study is to investigate variations in crude ICU mortality among patients with VAP over the past decade. We also wish to identify associated risk factors, evaluate changes in the etiology, and assess the incidence and impact of inappropriate empirical antibiotic treatment (IEAT). Methods: We conducted a retrospective, observational, single-center study over a 10-year period (2014–2024), including critically ill patients who developed VAP. The population was divided into three periods: (P1) from 2014 to 2018 (pre-COVID-19); (P2) from 2019 to 2021 (COVID-19); and (P3) from 2022 to 2024 (post-COVID-19). Binary logistic regression was used to identify which variables were independently associated with ICU mortality. Results: A total of 220 patients were included in the study (P1 = 47, P2 = 96, and P3 = 77 patients). The most prevalent microorganisms identified were P. aeruginosa, Klebsiella spp., and S. aureus. Significant variations in etiology were not observed over the years. The incidence of IEAT was 4.5%, with no observed differences between the study periods. Crude ICU mortality was 33.6%, with higher rates observed in IEAT (40% vs. 33.3%, p = 0.73). In patients with appropriate empiric antibiotic treatment (AEAT), there was a significant decrease in crude mortality over the years from 42.2% in P1 to 22.2% in P3 (p < 0.001). Age (OR = 1.04; 95% CI = 1.01–1.08) and P2 (OR = 2.8; 95% CI = 1.1–7.4) were found to be independently associated with an increased risk of mortality. Conversely, a lower risk of death was associated with mean arterial pressure (OR = 0.94; 95% CI = 0.69–0.99) and the use of syndromic respiratory panel (OR = 0.23; 95% CI = 0.07–0.68). Conclusions: A reduction in crude VAP mortality over the years was observed, with no change in the etiology or rate of IEAT. The implementation of protocols using respiratory syndromic panels could be a measure to implement to reduce VAP mortality. Full article