Biomechanical analysis of the tandem spinal external fixation in a multiple-level noncontiguous lumbar fractures model: a finite element analysis.

Objective: This study aimed to investigate the biomechanical characteristics of the tandem spinal external fixation (TSEF) for treating multilevel noncontiguous spinal fracture (MNSF) using finite element analysis and provide a theoretical basis for clinical application. Methods: We constructed two models of L2 and L4 vertebral fractures that were fixed with the TSEF and the long-segment spinal inner fixation (LSIF). The range of motion (ROM), maximum stresses at L2 and L4 vertebrae, the screws and rods, and the intervertebral discs of the two models were recorded under load control. Subsequently, the required torque, the maximum stress at L2 and L4 vertebrae, the screws and rods, and the intervertebral discs were analyzed under displacement control. Results: Under load control, the TSEF model reserved more ROM than the LSIF model. The maximum stresses of screws in the TSEF model were increased, while the maximum stresses of rods were reduced compared to the LSIF model. Moreover, the maximum stresses of L2 and L4 vertebrae and discs in the TSEF model were increased compared to the LSIF model. Under displacement control, the TSEF model required fewer moments (N·mm) than the LSIF model. Compared to the LSIF model, the maximum stresses of screws and rods in the TSEF model have decreased; the maximum stresses at L2 and L4 in the TSEF model were increased. In the flexion condition, the maximum stresses of discs in the TSEF model were less than the LSIF model, while the maximum stresses of discs in the TSEF model were higher in the extension condition. Conclusion: Compared to LSIF, the TSEF has a better stress distribution with higher overall mobility. Theoretically, it reduces the stress concentration of the connecting rods and the stress shielding of the fractured vertebral bodies.

Is Type 2 Diabetes Mellitus Associated with Spinal Degenerative Disorders?: Evidence from Observational and 2-Sample Mendelian Randomization Analyses.

BACKGROUND: Type 2 diabetes mellitus (T2DM) and spinal degenerative disorders (SDD) are common diseases that frequently coexist. However, both traditional observational studies and recent Mendelian randomization (MR) studies have demonstrated conflicting evidence on the association between T2DM and SDD. This comparative study explored and compared the association between T2DM and SDD using observational and MR analyses. METHODS: For observational analyses, cross-sectional studies (44,972 participants with T2DM and 403,095 participants without T2DM), case-control studies (38,234 participants with SDD and 409,833 participants without SDD), and prospective studies (35,550 participants with T2DM and 392,046 participants without T2DM with follow-up information until 2022) were performed to test the relationship between T2DM and SDD using individual-level data from the U.K. Biobank from 2006 to 2022. For MR analyses, the associations between single-nucleotide polymorphisms with SDD susceptibility obtained using participant data from the U.K. Biobank, which had 407,938 participants from 2006 to 2022, and the FinnGen Consortium, which had 227,388 participants from 2017 to 2022, and genetic predisposition to T2DM obtained using summary statistics from a pooled genome-wide association study involving 1,407,282 individuals were examined. The onset and severity of T2DM are not available in the databases being used. RESULTS: Participants with T2DM were more likely to have SDD than their counterparts. Logistic regression analysis identified T2DM as an independent risk factor for SDD, which was confirmed by the Cox proportional hazard model results. However, using single-nucleotide polymorphisms as instruments, the MR analyses demonstrated no causal relationship between T2DM and SDD. The lack of such an association was robust in the sensitivity analysis, and no pleiotropy was seen. CONCLUSIONS: Our results suggest that the association between T2DM and SDD may be method-dependent. Researchers and clinicians should be cautious in interpreting the association, especially the causal association, between T2DM and SDD. Our findings provide fresh insights into the association between T2DM and SDD by various analysis methods and guide future research and clinical efforts in the effective prevention and management of T2DM and SDD. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Single-cell RNA sequencing reveals the MIF/ACKR3 receptor-ligand interaction between neutrophils and nucleus pulposus cells in intervertebral disc degeneration.

OBJECTIVES: To unravel the heterogeneity and function of microenvironmental neutrophils during intervertebral disc degeneration (IDD). METHODS: Single-cell RNA sequencing (scRNA-seq) was utilized to dissect the cellular landscape of neutrophils in intervertebral disc (IVD) tissues and their crosstalk with nucleus pulposus cells (NPCs). The expression levels of macrophage migration inhibitory factor (MIF) and ACKR3 in IVD tissues were detected. The MIF/ACKR3 axis was identified and its effects on IDD were investigated in vitro and in vivo. RESULTS: We sequenced here 71520 single cells from 5 control and 9 degenerated IVD samples using scRNA-seq. We identified a unique cluster of neutrophils abundant in degenerated IVD tissues that highly expressed MIF and was functionally enriched in extracellular matrix organization (ECMO). Cell-to-cell communication analyses showed that this ECMO-neutrophil subpopulation was closely interacted with an effector NPCs subtype, which displayed high expression of ACKR3. Further analyses revealed that MIF was positively correlated with ACKR3 and functioned via directly binding to ACKR3 on effector NPCs. MIF inhibition attenuated degenerative changes of NPCs and extracellular matrix, which could be partially reversed by ACKR3 overexpression. Clinically, a significant correlation of high MIF/ACKR3 expression with advanced IDD grade was observed. Furthermore, we also found a positive association between MIF+ ECMO-neutrophil counts and ACKR3+ effector NPCs density as well as higher expression of the MIF/ACKR3 signaling in areas where these two cell types were neighbors. CONCLUSIONS: These data suggest that ECMO-neutrophil promotes IDD progression by their communication with NPCs via the MIF/ACKR3 axis, which may shed light on therapeutic strategies.

Apoptosis Signal-Regulated Kinase-1 Promotes Nucleus Pulposus Cell Senescence and Apoptosis to Regulate Intervertebral Disc Degeneration.

This study investigated the role of apoptosis signal-regulated kinase-1 (ASK1) in intervertebral disc degeneration (IDD). The nucleus pulposus (NP) tissues of non-IDD and IDD patients were subjected to hematoxylin and eosin, Safranin O-fast green, and immunohistochemical staining. Quantitative real-time PCR was used to assess the ASK1 mRNA level within NP tissue samples and cells. The Cell Counting Kit-8 assay, senescence-associated ß-galactosidase staining, and then flow cytometry were conducted, respectively, to assess the viability, senescence, and apoptosis of NP cells. The extracellular matrix-related factors were detected using Western blot analysis. Furthermore, the effect of ASK1 on the IDD rat model was evaluated through nuclear magnetic resonance imaging analysis, hematoxylin and eosin, Safranin O-fast green staining, and immunohistochemical staining. Finally, c-Jun N-terminal kinase (JNK) inhibitors were used to verify the effect of the JNK/p38 signaling on IDD. ASK1 mRNA and protein were up-regulated within NP tissue samples from the IDD group, IL-1ß-stimulated NP cells, and IDD rats. ASK1 inhibition promoted cell viability and repressed the senescence and apoptosis of NP cells; promoted collagen II and aggrecan; inhibited matrix metalloproteinase 3, matrix metalloproteinase 9, a disintegrin and metalloproteinase with thrombospondin motifs 4, and a disintegrin and metalloproteinase with thrombospondin motifs 5 protein levels; and increased NP cells in rat intervertebral disc tissues. ASK1 overexpression exerted the opposite effects of ASK1 inhibition on NP cells. Additionally, JNK/p38 signaling suppression could reverse the ASK1 up-regulation-induced dysfunction. In conclusion, ASK1 facilitated the senescence and apoptosis of NP cells in promoting IDD progression, which may be mediated by the JNK/p38 pathway.

Complex immune microenvironment of chordoma: a road map for future treatment.

BACKGROUND: Chordoma, a rare bone tumor, presents limited treatment options and patients typically exhibit poor survival outcomes. While immunotherapy has shown promising results in treating various tumors, research on the immune microenvironment of chordomas is still in its early stages. Therefore, understanding how the immune microenvironment of chordomas influences the outcomes of immunotherapy is crucial. METHODS: We employed single-cell RNA sequencing (scRNA-seq), bulk RNA-seq, CellChat, gene set variation analysis, as well as calculation of immune features to further dissect the complex immune microenvironment of chordoma. RESULTS: Previous research by van Oost et al argued that compared with other sarcomas, chordomas typically exhibit an immunologically "hot" microenvironment, a conclusion with which we concur based on their research findings. Additionally, the authors suggest that T cell-mediated immunotherapy is feasible for the majority of chordomas. However, we are inclined to categorize them as an immune-excluded phenotype according to the latest classification methods, rather than persisting with the concepts of "cold" and "hot". Unlike them, we explored immune infiltration scores (IS), T lymphocyte scoring (TLS), and human leucocyte antigen class I (HLA-I) using Bulk RNA-seq data from 126 chordoma patients and found that higher IS, TLS, and higher HLA-I expression were associated with poorer patient prognosis. Additionally, CellChat analysis of scRNA-seq results from six chordoma patients revealed no direct interaction between T cells and tumor cells. CONCLUSIONS: These findings suggested that the efficacy of T cell-based immunotherapy may be limited or even ineffective for patients with chordoma.

Clonal transmission of blaIMP-4-carrying ST196 Klebsiella pneumoniae isolates mediated by the IncN plasmid in China.

OBJECTIVES: To investigate the clinical and molecular epidemiological characteristics of blaIMP-4-carrying Klebsiella pneumoniae in a tertiary hospital in China. METHODS: Ten carbapenem-resistant K. pneumoniae (CRKP) isolates carrying the blaIMP-4 gene were collected. Molecular characteristics were analysed using whole-genome sequencing. Plasmid conjugation experiments were used to analyse conjugation of the plasmids. We compared and analysed K. pneumoniae-carrying blaIMP-4 genomic datasets obtained from the National Center for Biotechnology Information (NCBI) with the strains in this study. RESULTS: All 10 CRKP isolates carrying blaIMP-4 were collected from 10 adult patients in the respiratory intensive care unit. These strains were only sensitive to polymyxins and tigecycline due to them simultaneously carrying multiple resistance genes, namely blaOKP-A-5, fosA, oqxA, and oqxB. Notably, R29 harboured two carbapenemase genes (blaNDM-1 and blaIMP-4). These strains had similar drug-resistant phenotypes and genes, all belonging to sequence type (ST)196. Additionally, the patients had experienced spatiotemporal intersection during hospitalization, suggesting that these strains underwent clonal transmission, but they belonged to different clonal clusters from the blaIMP-4-positive K. pneumoniae currently published in the NCBI. Among the 10 strains, blaIMP-4 was located on the IncN plasmid, and six strains had successfully transferred the plasmid to the recipient strain EC600 through plasmid conjugation. CONCLUSIONS: The blaIMP-4-positive ST196 CRKP isolate showed clonal distribution in the respiratory intensive care unit, which was mediated by the IncN plasmid. Consequently, there should be increased monitoring of carbapenem-resistant strains in clinical settings to prevent and control its transmission.

Pangenome analysis of Shewanella xiamenensis revealed important genetic traits concerning genetic diversity, pathogenicity and antibiotic resistance.

BACKGROUND: Shewanella xiamenensis, widely distributed in natural environments, has long been considered as opportunistic pathogen. Recently, significant changes in the resistance spectrum have been observed in S. xiamenensis, due to acquired antibiotic resistance genes. Therefore, a pan-genome analysis was conducted to illuminate the genomic changes in S. xiamenensis. RESULTS: Phylogenetic analysis revealed three major clusters and three singletons, among which close relationship between several strains was discovered, regardless of their host and niches. The "open" genomes with diversity of accessory and strain-specific genomes took advantage towards diversity environments. The purifying selection pressure was the main force on genome evolution, especially in conservative genes. Only 53 gene families were under positive selection pressure. Phenotypic resistance analysis revealed 21 strains were classified as multi-drug resistance (MDR). Ten types of antibiotic resistance genes and two heavy metal resistance operons were discovered in S. xiamenensis. Mobile genetic elements and horizontal gene transfer increased genome diversity and were closely related to MDR strains. S. xiamenensis carried a variety of virulence genes and macromolecular secretion systems, indicating their important roles in pathogenicity and adaptability. Type IV secretion system was discovered in 15 genomes with various sequence structures, indicating it was originated from different donors through horizontal gene transfer. CONCLUSIONS: This study provided with a detailed insight into the changes in the pan-genome of S. xiamenensis, highlighting its capability to acquire new mobile genetic elements and resistance genes for its adaptation to environment and pathogenicity to human and animals.

Molecular characterization of extensively drug-resistant hypervirulent Pseudomonas aeruginosa isolates in China.

BACKGROUND: Recently, extensively drug-resistant Pseudomonas aeruginosa (XDR-PA) isolates have been increasingly detected and posed great challenges to clinical anti-infection treatments. However, little is known about extensively resistant hypervirulent P. aeruginosa (XDR-hvPA). In this study, we investigate its epidemiological characteristics and provide important basis for preventing its dissemination. METHODS: Clinical XDR-PA isolates were collected from January 2018 to January 2023 and identified using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry; antibiotic susceptibility testing was performed by broth microdilution method, and minimum inhibitory concentrations (MICs) were evaluated. Virulence was evaluated using the Galleria mellonella infection model; molecular characteristics, including resistance genes, virulence genes, and homology, were determined using whole-genome sequencing. RESULTS: A total of 77 XDR-PA strains were collected; 47/77 strains were XDR-hvPA. Patients aged > 60 years showed a significantly higher detection rate of XDR-hvPA than of XDR-non-hvPA. Among the 47 XDR-hvPA strains, 24 strains carried a carbapenemase gene, including blaGES-1 (10/47), blaVIM-2 (6/47), blaGES-14 (4/47), blaIMP-45 (2/47), blaKPC-2 (1/47), and blaNDM-14 (1/47). ExoU, exoT, exoY, and exoS, important virulence factors of PA, were found in 31/47, 47/47, 46/47, and 29/47 strains, respectively. Notably, two XDR-hvPA simultaneously co-carried exoU and exoS. Six serotypes (O1, O4-O7, and O11) were detected; O11 (19/47), O7 (13/47), and O4 (9/47) were the most prevalent. In 2018-2020, O4 and O7 were the most prevalent serotypes; 2021 onward, O11 (16/26) was the most prevalent serotype. Fourteen types of ST were detected, mainly ST235 (14/47), ST1158 (13/47), and ST1800 (7/47). Five global epidemic ST235 XDR-hvPA carried blaGES and showed the MIC value of ceftazidime/avibactam reached the susceptibility breakpoint (8/4 mg/L). CONCLUSIONS: The clinical detection rate of XDR-hvPA is unexpectedly high, particularly in patients aged > 60 years, who are seemingly more susceptible to contracting this infection. Clonal transmission of XDR-hvPA carrying blaGES, which belongs to the global epidemic ST235, was noted. Therefore, the monitoring of XDR-hvPA should be strengthened, particularly for elderly hospitalized patients, to prevent its spread.

Cardiovascular-specific mortality and risk factors in colorectal Cancer patients: A cohort study based on registry data of over 500,000 individuals in the US.

BACKGROUND: Colorectal cancer (CRC) is one of the most common cancers worldwide, and recent studies have found that CRC patients are at increased risk for cardiovascular disease (CVD). This study aimed to investigate competing causes of death and prognostic factors among a large cohort of CRC patients and to describe cardiovascular-specific mortality in relation to the US standard population. METHODS: This registry-based cohort study identified patients diagnosed with CRC between 1973 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) database in the US. Cumulative mortality functions, conditional standardized mortality ratios, and cause-specific hazard ratios were calculated. RESULTS: Of the 563,298 eligible CRC patients included in this study, 407,545 died during the follow-up period. CRC was the leading cause of death, accounting for 49.8% of all possible competing causes of death. CVD was the most common non-cancer cause of death, accounting for 17.8% of total mortality. This study found that CRC patients have a significantly increased risk of cardiovascular-specific mortality compared to the US standard population, with the risk increasing with age and extended survival time. CONCLUSION: This study highlights the need to develop multidisciplinary prevention and management strategies for CRC and CVD to improve CRC patients' survival and quality of life.

Integrating single-cell and spatial transcriptomics reveals endoplasmic reticulum stress-related CAF subpopulations associated with chordoma progression.

BACKGROUND: With cancer-associated fibroblasts (CAFs) as the main cell type, the rich myxoid stromal components in chordoma tissues may likely contribute to its development and progression. METHODS: Single-cell RNA sequencing (scRNA-seq), spatial transcriptomics, bulk RNA-seq, and multiplexed quantitative immunofluorescence (QIF) were used to dissect the heterogeneity, spatial distribution, and clinical implication of CAFs in chordoma. RESULTS: We sequenced here 72 097 single cells from 3 primary and 3 recurrent tumor samples, as well as 3 nucleus pulposus samples as controls using scRNA-seq. We identified a unique cluster of CAF in recurrent tumors that highly expressed hypoxic genes and was functionally enriched in endoplasmic reticulum stress (ERS). Pseudotime trajectory and cell communication analyses showed that this ERS-CAF subpopulation originated from normal fibroblasts and widely interacted with tumoral and immune cells. Analyzing the bulk RNA-seq data from 126 patients, we found that the ERS-CAF signature score was associated with the invasion and poor prognosis of chordoma. By integrating the results of scRNA-seq with spatial transcriptomics, we demonstrated the existence of ERS-CAF in chordoma tissues and revealed that this CAF subtype displayed the most proximity to its surrounding tumor cells. In subsequent QIF validation involving 105 additional patients, we confirmed that ERS-CAF was abundant in the chordoma microenvironment and located close to tumor cells. Furthermore, both ERS-CAF density and its distance to tumor cells were correlated with tumor malignant phenotype and adverse patient outcomes. CONCLUSIONS: These findings depict the CAF landscape for chordoma and may provide insights into the development of novel treatment approaches.

A breast cancer classification and immune landscape analysis based on cancer stem-cell-related risk panel.

This study sought to identify molecular subtypes of breast cancer (BC) and develop a breast cancer stem cells (BCSCs)-related gene risk score for predicting prognosis and assessing the potential for immunotherapy. Unsupervised clustering based on prognostic BCSC genes was used to determine BC molecular subtypes. Core genes of BC subtypes identified by non-negative matrix factorization algorithm (NMF) were screened using weighted gene co-expression network analysis (WGCNA). A risk model based on prognostic BCSC genes was constructed using machine learning as well as LASSO regression and multivariate Cox regression. The tumor microenvironment and immune infiltration were analyzed using ESTIMATE and CIBERSORT, respectively. A CD79A+CD24-PANCK+-BCSC subpopulation was identified and its spatial relationship with microenvironmental immune response state was evaluated by multiplexed quantitative immunofluorescence (QIF) and TissueFAXS Cytometry. We identified two distinct molecular subtypes, with Cluster 1 displaying better prognosis and enhanced immune response. The constructed risk model involving ten BCSC genes could effectively stratify patients into subgroups with different survival, immune cell abundance, and response to immunotherapy. In subsequent QIF validation involving 267 patients, we demonstrated the existence of CD79A+CD24-PANCK+-BCSC in BC tissues and revealed that this BCSC subtype located close to exhausted CD8+FOXP3+ T cells. Furthermore, both the densities of CD79A+CD24-PANCK+-BCSCs and CD8+FOXP3+T cells were positively correlated with poor survival. These findings highlight the importance of BCSCs in prognosis and reshaping the immune microenvironment, which may provide an option to improve outcomes for patients.

Global cluster analysis and network visualization in cancer-associated fibroblast: insights from Web of Science database from 1999 to 2021.

BACKGROUND: A scientific and comprehensive analysis of the current status and trends in the field of cancer-associated fibroblast (CAF) research is worth investigating. This study aims to investigate and visualize the development, research frontiers, and future trends in CAFs both quantitatively and qualitatively based on a bibliometric approach. METHODS: A total of 5518 publications were downloaded from the Science Citation Index Expanded of Web of Science Core Collection from 1999 to 2021 and identified for bibliometric analysis. Visualized approaches, OriginPro (version 9.8.0.200) and R (version 4.2.0) software tools were used to perform bibliometric and knowledge-map analysis. RESULTS: The number of publications on CAFs increased each year, and the same tendency was observed in the RRI. Apart from China, the countries with the largest number of publications and the most cited frequency were mainly Western developed countries, especially the USA. Cancers was the journal with the largest number of articles published in CAFs, and Oncology was the most popular research orientation. The most productive author was Lisanti MP, and the University of Texas System was ranked first in the institutions. In addition, the topics of CAFs could be divided into five categories, including tumor classification, prognostic study, oncologic therapies, tumor metabolism and tumor microenvironment. CONCLUSIONS: This is the first thoroughly scientific bibliometric analysis and visualized study of the global research field on CAFs over the past 20 years. The study may provide benefits for researchers to master CAFs' dynamic evolution and research trends.

Clinicopathological characteristics and prognostic factors in axial chondroblastomas: a retrospective analysis of 61 cases and comparison with extra-axial chondroblastomas.

BACKGROUND: A comprehensive understanding of the clinical characteristics and prognostic factors associated with axial chondroblastoma (ACB) is still lacking. This study aimed to understand the clinical characteristics and prognostic factors of axial chondroblastoma (ACB) and compare them with extra-axial chondroblastoma (EACB). METHODS: A retrospective review of our institution's local database was conducted, encompassing a total of 132 CB patients, of which 61 were diagnosed with ACB and 71 with EACB. Immunohistochemistry was employed to evaluate the expression levels of vimentin, S100, and cytokeratin. RESULTS: ACB and EACB shared similar characteristics, with the exception of advanced age, tumor size, elevated Vim expression, incidence of surrounding tissue invasion, and postoperative sensory or motor dysfunction. While wide resection and absence of surrounding tissue invasion consistently showed a favorable association with survival in both ACB and EACB cohorts during univariate analysis, most parameters exhibited differential prognostic significance between the two groups. Notably, the significant prognostic factors for local recurrence-free survival in the ACB cohort included the type of resection and the presence of chicken-wire calcification. In the multivariate analysis of overall survival, the type of resection emerged as a significant predictor in the ACB cohort, whereas in the EACB group, the type of resection and the occurrence of postoperative sensory or motor dysfunction were predictive of overall survival. CONCLUSION: There may exist distinct biological behaviors between ACB and EACB, thereby providing valuable insights into the prognostic characteristics of ACB patients and contributing to enhanced outcome prediction in this particular patient population.

ChatGPT encounters multiple opportunities and challenges in neurosurgery.

BACKGROUND: ChatGPT, powered by the GPT model and Transformer architecture, has demonstrated remarkable performance in the domains of medicine and healthcare, providing customized and informative responses. In our study, we investigated the potential of ChatGPT in the field of neurosurgery, focusing on its applications at the patient, neurosurgery student/resident, and neurosurgeon levels. METHOD: The authors conducted inquiries with ChatGPT from the viewpoints of patients, neurosurgery students/residents, and neurosurgeons, covering a range of topics, such as disease diagnosis, treatment options, prognosis, rehabilitation, and patient care. The authors also explored concepts related to neurosurgery, including fundamental principles and clinical aspects, as well as tools and techniques to enhance the skills of neurosurgery students/residents. Additionally, the authors examined disease-specific medical interventions and the decision-making processes involved in clinical practice. RESULTS: The authors received individual responses from ChatGPT, but they tended to be shallow and repetitive, lacking depth and personalization. Furthermore, ChatGPT may struggle to discern a patient's emotional state, hindering the establishment of rapport and the delivery of appropriate care. The language used in the medical field is influenced by technical and cultural factors, and biases in the training data can result in skewed or inaccurate responses. Additionally, ChatGPT's limitations include the inability to conduct physical examinations or interpret diagnostic images, potentially overlooking complex details and individual nuances in each patient's case. Moreover, its absence in the surgical setting limits its practical utility. CONCLUSION: Although ChatGPT is a powerful language model, it cannot substitute for the expertise and experience of trained medical professionals. It lacks the capability to perform physical examinations, make diagnoses, administer treatments, establish trust, provide emotional support, and assist in the recovery process. Moreover, the implementation of Artificial Intelligence in healthcare necessitates careful consideration of legal and ethical concerns. While recognizing the potential of ChatGPT, additional training with comprehensive data is necessary to fully maximize its capabilities.

Corrigendum: Coexpression of HHLA2 and PD-L1 on tumor cells independently predicts the survival of spinal chordoma patients.

[This corrects the article DOI: 10.3389/fimmu.2021.797407.].

Biosynthesis of Silver Nanoparticles Using the Biofilm Supernatant of Pseudomonas aeruginosa PA75 and Evaluation of Their Antibacterial, Antibiofilm, and Antitumor Activities.

Purpose: As an under-explored biomaterial, bacterial biofilms have a wide range of applications in the green synthesis of nanomaterials. The biofilm supernatant of Pseudomonas aeruginosa PA75 was used to synthesize novel silver nanoparticles (AgNPs). BF75-AgNPs were found to possess several biological properties. Methods: In this study, we biosynthesized BF75-AgNPs using biofilm supernatant as the reducing agent, stabilizer, and dispersant and investigated their biopotential in terms of antibacterial, antibiofilm, and antitumor activities. Results: The synthesized BF75-AgNPs demonstrated a typical face-centered cubic crystal structure; they were well dispersed; and they were spherical with a size of 13.899 ± 4.036 nm. The average zeta potential of the BF75-AgNPs was -31.0 ± 8.1 mV. The BF75-AgNPs exhibited strong antibacterial activities against the methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum beta-lactamase Escherichia coli (ESBL-EC), extensively drug-resistant Klebsiella pneumoniae (XDR-KP), and carbapenem-resistant Pseudomonas aeruginosa (CR-PA). Moreover, the BF75-AgNPs had a strong bactericidal effect on XDR-KP at 1/2 × MIC, and the expression level of reactive oxygen species (ROS) in bacteria was significantly increased. A synergistic effect was observed when the BF75-AgNPs and colistin were used for the co-treatment of two colistin-resistant XDR-KP strains, with fractional inhibitory concentration index (FICI) values of 0.281 and 0.187, respectively. Furthermore, the BF75-AgNPs demonstrated a strong biofilm inhibition activity and mature biofilm bactericidal activity against XDR-KP. The BF75-AgNPs also exhibited a strong antitumor activity against melanoma cells and low cytotoxicity against normal epidermal cells. In addition, the BF75-AgNPs increased the proportion of apoptotic cells in two melanoma cell lines, and the proportion of late apoptotic cells increased with BF75-AgNP concentration. Conclusion: This study suggests that BF75-AgNPs synthesized from biofilm supernatant have broad prospects for antibacterial, antibiofilm, and antitumor applications.

Metagenomic analysis reveals the short-term influences on conjugation of blaNDM-1 and microbiome in hospital wastewater by silver nanoparticles at environmental-related concentration.

Hospital wastewater contains large amounts of antibiotic-resistant bacteria and serves as an important reservoir for horizontal gene transfer (HGT). However, the response of the microbiome in hospital wastewater to silver remains unclear. In this study, the short-term impacts of silver on the microbiome in hospital wastewater were investigated by metagenome next-generation sequencing. The influence of silver on the conjugation of plasmid carrying blaNDM-1 was further examined. Our results showed that in hospital wastewater, high abundances of antibiotic resistance genes (ARGs) were detected. The distribution tendencies of certain ARG types on chromosomes or plasmids were different. Clinically important ARGs were identified in phage-like contigs, indicating potential transmission via transduction. Pseudomonadales, Enterobacterales, and Bacteroidales were the major ARG hosts. Mobile genetic elements were mainly detected in plasmids and associated with various types of ARGs. The binning approach identified 29 bins that were assigned to three phyla. Various ARGs and virulence factors were identified in 14 and 11 bins, respectively. MetaCHIP identified 49 HGT events. The transferred genes were annotated as ARGs, mobile genetic elements, and functional genes, and they mainly originated from donors belonging to Bacteroides and Pseudomonadales. In addition, 20 nm AgNPs reduced microbial diversity and enhanced the relative abundance of Acinetobacter. The changes induced by 20 nm AgNPs included increases in the abundances of ARGs and genes involved lipid metabolism pathway. Conjugation experiments showed that Ag+ and 20 nm AgNPs caused 2.38-, 3.31-, 4.72-, and 4.57-fold and 1.46-, 1.61-, 3.86-, and 2.16-fold increases in conjugation frequencies of plasmid with blaNDM-1 at 0.1, 1, 10, and 100 µg/L, respectively. Our findings provide insight into the response of the microbiome in hospital wastewater to silver, emphasize the adaptation capability of Acinetobacter inhabiting hospitals against adverse environments, and highlight the promotion of silver for antibiotic resistance.

Clonal transmission of polymyxin B-resistant hypervirulent Klebsiella pneumoniae isolates coharboring blaNDM-1 and blaKPC-2 in a tertiary hospital in China.

BACKGROUND: The prevalence of multidrug-resistant hypervirulent K. pneumoniae (MDR-hvKP) has gradually increased. It poses a severe threat to human health. However, polymyxin-resistant hvKP is rare. Here, we collected eight polymyxin B-resistant K. pneumoniae isolates from a Chinese teaching hospital as a suspected outbreak. RESULTS: The minimum inhibitory concentrations (MICs) were determined by the broth microdilution method. HvKP was identified by detecting virulence-related genes and using a Galleria mellonella infection model. Their resistance to serum, growth, biofilm formation, and plasmid conjugation were analyzed in this study. Molecular characteristics were analyzed using whole-genome sequencing (WGS) and mutations of chromosome-mediated two-component systems pmrAB and phoPQ, and the negative phoPQ regulator mgrB to cause polymyxin B (PB) resistance were screened. All isolates were resistant to polymyxin B and sensitive to tigecycline; four were resistant to ceftazidime/avibactam. Except for KP16 (a newly discovered ST5254), all were of the K64 capsular serotype and belonged to ST11. Four strains co-harbored blaKPC-2, blaNDM-1, and the virulence-related genes prmpA, prmpA2, iucA, and peg344, and were confirmed to be hypervirulent by the G. mellonella infection model. According to WGS analysis, three hvKP strains showed evidence of clonal transmission (8-20 single nucleotide polymorphisms) and had a highly transferable pKOX_NDM1-like plasmid. KP25 had multiple plasmids carrying blaKPC-2, blaNDM-1, blaSHV-12, blaLAP-2, tet(A), fosA5, and a pLVPK-like virulence plasmid. Tn1722 and multiple additional insert sequence-mediated transpositions were observed. Mutations in chromosomal genes phoQ and pmrB, and insertion mutations in mgrB were major causes of PB resistance. CONCLUSIONS: Polymyxin-resistant hvKP has become an essential new superbug prevalent in China, posing a serious challenge to public health. Its epidemic transmission characteristics and mechanisms of resistance and virulence deserve attention.