Feng Wang

Background: The emergence of linezolid−resistant methicillin−susceptible Staphylococcus aureus (MSSA) is a growing clinical threat, but the underlying mechanisms are unclear. Here, we generated stable resistant derivatives and used a multi−omics strategy to investigate the transcriptional and metabolic regulation underlying linezolid resistance in MSSA. Methods: A clinical isolate of linezolid-susceptible S. aureus (strain S. aureus _97) was used as the parental strain. A stable linezolid-resistant derivative (designated LZR) was generated through stepwise induction with subinhibitory concentrations of linezolid. The genetic stability of the resistant phenotype was subsequently confirmed via phenotypic stability assays. To elucidate the mechanisms underlying resistance, comparative transcriptomic (RNA-seq) and untargeted metabolomic (LC-MS/MS) analyses were performed to identify differential gene expression and metabolic profiles between the resistant (LZR) and susceptible (LSS) strains. Results: The successfully induced linezolid-resistant derivative (LZR) exhibited a 16-fold increase in minimum inhibitory concentration (MIC) against linezolid (32 μg/mL) compared with the parental strain (2 μg/mL), and this resistant phenotype remained stable after 50 serial passages in antibiotic-free medium. CCCP was observed to reduce the MIC of LZR in a concentration-dependent manner. Transcriptomic and metabolomic analyses revealed widespread transcriptional reprogramming and metabolic perturbations in the resistant strain. Differentially expressed genes were mainly enriched in pathways associated with oxidative phosphorylation, ribosome function, and glycerolipid metabolism, while differential metabolites were primarily involved in the biosynthesis of secondary metabolites and amino acid metabolism. Integrated analysis identified key co-enriched pathways with distinct regulatory patterns, which collectively remodeled bacterial material and energy metabolism and were closely associated with the emergence of linezolid resistance. Conclusion: A stable linezolid-resistant MSSA strain was developed in this work, revealing an intricate network of regulatory interactions that drive resistance at both the transcriptional and metabolic levels. These findings provide an experimental foundation and theoretical basis for further understanding the mechanisms of linezolid resistance in MSSA and for developing strategies to combat resistance.

Objective: Objective: This study investigated the antimicrobial resistance profile of carbapenem-resistant Pseudomonas aeruginosa (CRPA) and its association with the T3SS, aiming to provide evidence for managing highly resistant and virulent CRPA and to guide the optimization of infection control strategies. Methods: Retrospective cohort study was performed with CRPA lower respiratory tract infection from a tertiary hospital (July, 2021, and May, 2025). All strains underwent whole-genome sequencing (WGS), antimicrobial susceptibility testing(AST); selected isolates’ virulence were further evaluated using galleria mellonella infection assays. Results: Among 106 patients caused by CRPA infections, the majority were male (73.6%), with a median age of 69.5 years and median hospital stay of 26.5 days. Prior antibiotic exposure included piperacillin/tazobactam (57.5%) and carbapenems (49.1%). AST revealed high resistance to piperacillin/tazobactam, but favorable susceptibility to ceftazidime/avibactam and tobramycin, with no polymyxin B resistance. Multidrug resistance occurred in 49.1% of isolates, and 28.3% were difficult-to-treat Pseudomonas aeruginosa (DTR-PA). The exoU and exoS genes were detected in 28.3% and 64.2% of strains, respectively, with 7.5% co-detection. ExoU +/ exoS - strains showed significantly higher resistance to ceftazidime, cefepime, and piperacillin/tazobactam. All isolates had oprD mutations. Carbapenemase genes were found in 21.7%, primarily bla _KPC-3. ExoU+/exoS- strains were linked to bla _KPC-3 and bla _OXA-50 subtypes(OXA-488,OXA-1032), while exoU-/exoS+ strains associated with bla _OXA-486 and bla _OXA-904 . Among 59 sequence types, ST1076 (13.2%) and ST491 (10.4%) dominated, with serotypes O11 (38.7%) and O6 (25.5%) prevalent. Six international high-risk clones included ST233, ST244, and ST357. Phylogenetically, phylogroup A ( exoU -/ exoS +, e.g., PAO1) was larger, and phylogroup B ( exoU +/ exoS -, e.g., PA14) included highly virulent strains. ExoU +/ exoS - strains grouped in ST1076 and ST357, and exoU +/ exoS + in ST463. The survival of galleria mellonella further indicated that carrying the exoU may cause a higher lethality rate. Conclusions: ExoU +/ exoS - strains were strongly associated with resistance genes like bla _KPC-3 , bla _OXA-488 , bla _OXA-1032 , ICU admission and exhibited a more pronounced drug-resistant phenotype. Potential high-risk clones such as ST1076-O11 and ST463-O4 display both extensive resistance and high virulence, underscoring the clinical and public health importance of enhanced surveillance and effective containment.

Background: Pediatric acute respiratory tract infection (ARTI) constitutes a major global health threat. Since 2020, global containment measures have disrupted pathogen circulation patterns, leading to altered epidemiological profiles across multiple pathogens with marked regional heterogeneity. Current research in Ningbo predominantly focuses on single-pathogen surveillance or short-term monitoring, lacking systematic analysis of multi-pathogen interactive dynamics, age-specific susceptibility mechanisms, and co-infections. Methods: Clinical data from all 191,967 pediatric patients with ARTI at Ningbo LiHuili Hospital (2020–2024) were collected. Laboratory testing including influenza A/B virus (IFV-A/B) detection, Mycoplasma pneumoniae (MP) testing, 13 respiratory pathogens analysis, and bacterial culture was systematically integrated and analyzed. Results: From 2020 and 2024, the number of ARTI cases initially increased and then decreased, peaking in 2023. The incidence was highest in autumn and lowest in summer. Among all cases, 75,001 (39.07%) were diagnosed with acute lower respiratory infection (ALRI), with children aged 6 years exhibiting the highest susceptibility. Of the 41,766 cases tested, the overall pathogen detection rate was 67.61%. IFV-A/B, Human Parainfluenza Virus (HPIV), and Human Adenovirus (HAdV) were more frequently detected in acute upper respiratory tract infections (AURI) ( P < 0.05), while Human Rhinovirus (HRV), Respiratory Syncytial Virus (RSV), and MP were predominantly identified in ALRI cases ( P < 0.05). Each pathogen exhibited age-specific susceptibility patterns. Several pathogens, such as IFV-A, MP, and HAdV, displayed distinctive epidemic peaks. Co-infections were common, with a 17.38% co-infection rate observed in the group tested for 13 respiratory pathogens, and a higher co-infection rate of 39.49% when testing combined respiratory pathogens and bacteria. Correlation analysis among pathogens revealed predominant antagonistic interactions between viruses, positive associations among bacteria, and generally positive interactions between viruses and bacteria, though overall correlation strengths were weak. Conclusion: Pediatric ARTI exhibit age-specific susceptibility and pathogen variation. The 2023–2024 resurgence demands precision control strategies for optimized intervention.

Gastric carcinoma is a frequently detected malignancy worldwide, while its mainstream drugs usually result in some adverse reactions, including immunosuppression. λ-carrageenan oligosaccharides (COS) have attracted increasing attention as potential anticancer agents due to their ability to enhance immune function. Our current work assessed the antitumor mechanism of λ-COS using BGC-823 cells. Our findings indicated that λ-COS alone did not have a significant impact on BGC-823 cells in vitro; however, it was effective in inhibiting tumor growth in vivo. When THP-1 cells were pre-incubated with λ-COS and used to condition the medium, BGC-823 cells in vitro displayed a concentration-dependent induction of cell apoptosis, nuclear damage, and the collapse of mitochondrial transmembrane potential. These findings suggested that the antineoplastic effect of λ-COS was primarily due to its immunoenhancement property. Treatment with λ-COS was found to significantly enhance the phagocytic capability of macrophages, increase the secretion of TNF-α and IFN-γ, and improve the indexes of spleen and thymus in BALB/c mice. In addition, λ-COS was found to inhibit the growth of BGC-823-derived tumors in vitro by activating the Par-4 signaling pathway, which may be stimulated by the combination of TNF-α and IFN-γ. When used in combination with 5-FU, λ-COS demonstrated enhanced anti-gastric carcinoma activity and improved the immunosuppression induced by 5-FU alone. These findings suggested that λ-COS could be used as an immune-modulating agent for chemotherapy.

High-fat (HF) diets and low-grade chronic inflammation contribute to the development of insulin resistance and type 2 diabetes (T2D), whereas n-3 polyunsaturated fatty acids (PUFAs), due to their anti-inflammatory effects, protect against insulin resistance. Interleukin (IL)-1β is implicated in insulin resistance, yet how n-3 PUFAs modulate IL-1β secretion and attenuate HF diet-induced insulin resistance remains elusive. In this study, a HF diet activated NLRP3 inflammasome via inducing reactive oxygen species (ROS) generation and promoted IL-1β production primarily from adipose tissue preadipocytes, but not from adipocytes and induced insulin resistance in wild type (WT) mice. Interestingly, endogenous synthesized n-3 polyunsaturated fatty acids (PUFAs) reversed this process in HF diet-fed fat-1 transgenic mice although the HF diet induced higher weight gain in fat-1 mice, compared with the control diet. Mechanistically, palmitic acid (PA), the main saturated fatty acid in an HF diet inactivated AMPK and led to decreased GSK-3β phosphorylation, at least partially through reducing Akt activity, which ultimately blocked the Nrf2/Trx1 antioxidant pathway and induced TXNIP cytoplasm translocation and NLRP3 inflammasome activation, whereas docosahexaenoic acid (DHA), the most abundant n-3 PUFA in fat-1 adipose tissue, reversed this process via inducing Akt activation. Our GSK-3β shRNA knockdown study further revealed that GSK-3β played a pivot role between the upstream AMPK/Akt pathway and downstream Nrf2/Trx1/TXNIP pathway. Given that NLRP3 inflammasome is implicated in the development of most inflammatory diseases, our results suggest the potential of n-3 PUFAs in the prevention or adjuvant treatment of NLRP3 inflammasome-driven diseases.