Search Results (256)

Background: Salmonella enterica, a major foodborne pathogen, poses a severe global public health threat. However, data regarding its carriage characteristics, transmission patterns, and association with intestinal microbiota in healthy populations of Xinjiang, China, remain insufficient, limiting the formulation of targeted salmonellosis prevention and control strategies. Methods: In this study, 31 Salmonella enterica strains isolated from more than 2000 healthy individuals in Urumqi were subjected to whole-genome sequencing to analyze serovars, antimicrobial resistance (AMR) genes, and virulence genes. Meanwhile, metagenomic sequencing was performed on 50 fecal samples (culture negative) from 2000 healthy individuals to investigate intestinal microbiota structure, Salmonella enterica prevalence, and related microbial taxa. Results: The results showed that 60% of samples (30/50) were positive by the read-based criterion (≥1000 Salmonella-specific reads), while the assembly-verified criterion (≥1000 reads and contigs > 1 kb) confirmed Salmonella-specific sequences in 12% (6/50). Among the 31 culture-confirmed isolates, Salmonella Typhimurium and Salmonella Paratyphi B were the dominant serovars, together accounting for 60%. All isolates harbored core virulence genes for Type III secretion system and adhesion factors, with low AMR gene carriage and no multidrug-resistant strains. Phylogenetic analysis showed that Urumqi-derived isolates were distributed across multiple genomic clusters, suggesting active inter-regional circulation of S. enterica within the available dataset. Salmonella enterica carriage did not affect gut microbial α-diversity but altered community composition, with Escherichia coli, Shigella flexneri, and Klebsiella pneumoniae as key associated taxa. Conclusions: This study found that Urumqi-derived isolates are widely distributed across genomic clusters in Xinjiang, with a unique local transmission chain identified, though definitive source attribution requires further geographically balanced sampling. Salmonella enterica carriage exhibited ecological niche synergy with intestinal Enterobacteriaceae, but did not significantly affect gut microbial diversity. Full article

Pseudomonas aeruginosa is a nosocomial pathogenic bacterium that causes a wide range of human infectious diseases. The type III secretion system (T3SS) serves as a key virulence determinant underlying the pathogenesis of this bacterium in acute infections. As the master transcriptional activator of T3SS, ExsA binds to target promoter regions and modulates the expression of all currently identified T3SS genes. In this study, we identified tyrosine phosphoprotein A (TypA) as a repressor that restricts expression of the T3SS in P. aeruginosa. TypA interacts with ExsA to block its binding to target promoters, thereby inhibiting T3SS expression. We show that the typA expression is induced in response to low calcium, low temperature, a biofilm lifestyle, and direct contact with host cells. Additionally, the absence of TypA caused a growth defect in P. aeruginosa at low temperatures. Collectively, these data confirm the significant role of TypA and reveal a novel molecular mechanism by which P. aeruginosa regulates T3SS. Full article

Eucalyptus bacterial wilt in China, caused predominantly by Ralstonia pseudosolanacearum, severely threatens Eucalyptus plantation management in China and demands plant-derived alternatives to conventional bactericides. This study evaluated the in vitro antibacterial activities and underlying molecular mechanisms of two differentially substituted coumarin derivatives, daphnetin (DAP) and 6-methylcoumarin (MC), against a eucalyptus-derived R. pseudosolanacearum strain. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using broth microdilution assays. Quantitative phenotypic assays were conducted to evaluate the effects of sub-lethal concentrations on biofilm formation, swimming motility, and extracellular polysaccharide (EPS) accumulation. Furthermore, high-throughput RNA sequencing integrated with GO and KEGG enrichment analyses was employed to characterize the genome-wide transcriptomic responses. Antimicrobial susceptibility testing demonstrated that DAP possessed superior bactericidal efficacy, yielding lower MIC (62.5 μg/mL) and MBC (250 μg/mL) values than MC. Conversely, sub-lethal MC exhibited a more pronounced, early-stage suppression of flagellum-dependent swimming motility and biofilm maturation. Both compounds consistently attenuated EPS production. Transcriptomic analysis revealed distinct yet partially convergent regulatory networks: DAP primarily exerted metabolic strangulation by downregulating genes governing aerobic respiratory chains and peripheral carbon/nitrogen pathways, whereas MC targeted collective behavior and active pathogenesis, systematically downregulating the expression of genes associated with flagellar assembly, quorum sensing, and Type III and VI secretion systems. Notably, both pathways converged downstream to repress the master virulence regulator xpsR and the epsA-P operon. These findings provide valuable insights into the potential molecular pathways affected by DAP and MC, offering a useful reference for future exploration of botanical formulations for ecologically responsible forest disease control. Full article

Understanding the metabolic basis of bacterial virulence is essential for developing anti-infective strategies. Phosphoenolpyruvate carboxykinase (PEPCK), encoded by pckA, is a key enzyme at the metabolic junction between the pyruvate cycle and the TCA cycle, but its role in virulence regulation remains largely unexplored. In this study, we generated a pckA deletion mutant, ΔpckA, in Edwardsiella tarda and investigated its impact on virulence, metabolism, and vaccine potential. The ΔpckA mutant exhibited increased antibiotic sensitivity, faster growth, reduced autoaggregation, and significantly attenuated virulence in a tilapia infection model. Quantitative proteomics revealed global downregulation of type III and type VI secretion systems (T3SS and T6SS) and upregulation of flagellar proteins. Mechanistically, accumulation of oxaloacetate (OAA) in the mutant suppressed T3SS/T6SS expression without affecting flagellar motility. Importantly, ΔpckA induced a robust immune response in zebrafish and conferred strong protection against lethal challenge, with relative percent survival values of 64% and 81.82% in zebrafish and tilapia, respectively. Taken together, our findings identify PEPCK as a critical metabolic regulator of E. tarda virulence and highlight ΔpckA as a promising live attenuated vaccine candidate. Full article

Ancient DNA and metagenomic studies provide valuable insights into microbial evolution, host–microbe interactions, and the ecology of ancient microbial communities; however, data from urban archaeological contexts remain limited. This study investigated microbial DNA preserved in paired petrous bone and adjacent sediment samples recovered from the Bath–Gymnasium complex of Stratonikeia, a Hellenistic–Roman city in western Anatolia, to characterize microbial diversity and functional gene profiles in an archaeological context. DNA was extracted under contamination-controlled conditions and analysed using high-throughput shotgun metagenomic sequencing. Bioinformatic analyses included taxonomic profiling, microbial diversity assessment, differential abundance analysis, and characterization of virulence-associated and antimicrobial resistance-related genes. The RH1MK1 (Tepidarium) samples exhibited greater microbial diversity and a higher relative abundance of bacterial taxa with recognized pathogenic potential, including Escherichia coli, Shigella flexneri, Vibrio cholerae, and Clostridioides difficile, compared with the SRH1PPG (Palaestra) samples. Virulence-associated genes, including Shiga toxin-, cholera toxin-, and type III secretion system-related sequences, together with antimicrobial resistance-associated genes, were more abundant in RH1MK1, consistent with differences in depositional and microenvironmental conditions between the two archaeological contexts. Comparative analyses revealed both shared and site-specific microbial profiles relative to other Anatolian archaeological sites. These findings demonstrate the potential of shotgun metagenomics for investigating preserved microbial DNA in archaeological materials while emphasizing that the detected microbial taxa and functional genes should be interpreted within their archaeological and depositional context rather than as direct evidence of ancient infectious diseases or epidemic events. Full article

Background: Lung infections represent a major cause of morbidity and mortality in patients with cystic fibrosis (CF) and are predominantly associated with chronic infection by Pseudomonas aeruginosa. The clinical management of CF lung disease is increasingly compromised by the emergence of multidrug-resistant strains, biofilm formation, and the expression of multiple virulence determinants. Antimicrobial peptides (AMPs), evolutionarily conserved effectors of innate immunity, have emerged as promising therapeutic candidates due to their ability to exert both bactericidal and anti-virulence activities. In this study, we investigated the antimicrobial and mechanistic effects of Ranalexin-1G, an AMP derived from the skin secretion of Rana grylio, against P. aeruginosa, for which its antibacterial activity has not previously been reported in the literature. Methods: Antibacterial activity was determined against the reference strain and three clinical isolates of P. aeruginosa by broth microdilution assays, time-kill kinetics and anti-biofilm assays, while peptide-mediated modulation of virulence was evaluated through transcriptional analysis of key virulence-associated genes by RT-PCR. The impact of Ranalexin-1G on host–pathogen interactions was further assessed using bacterial invasion assays in human bronchial epithelial cells (BEAS-2B). Results: Ranalexin-1G exerted a rapid bactericidal effect within 6 h at non-cytotoxic concentrations and displayed modest anti-biofilm effects, with greater efficacy in inhibiting biofilm formation. Mechanistically, peptide treatment resulted in a reduction in the expression of selected genes involved in biofilm formation and virulence, including those associated with alginate biosynthesis and type III secretion system-mediated cytotoxicity. Consistently, Ranalexin-1G markedly impaired bacterial invasion of epithelial cells, indicating interference with early host–pathogen interaction processes. Notably, the peptide displayed robust antimicrobial activity against multidrug-resistant P. aeruginosa clinical isolates from CF patients. Conclusions: Collectively, these findings suggest that Ranalexin-1G acts through a dual mechanism involving direct bactericidal activity and modulation of selected virulence pathways, supporting further investigation of its potential as an anti-virulence and host-directed approach for the treatment of chronic P. aeruginosa infections in cystic fibrosis. Full article

Diarrheal disease remains a significant public health concern in Bhutan; however, the genomic epidemiology of the circulating diarrhoeagenic Escherichia coli (DEC) strain remains poorly understood. This study characterized the genomic diversity, antimicrobial resistance (AMR), and virulence determinants of DEC isolates using whole-genome sequencing (WGS). DEC isolates recovered from stool samples and collected through Bhutan’s National Diarrheal Disease Surveillance sentinel hospitals during 2023 were identified by a multiplex polymerase chain reaction, tested for antimicrobial susceptibility using the Kirby–Bauer disc diffusion method, and sequenced on the Illumina MiSeq platform. Genomes were analyzed using the Bohra pipeline to determine pathotypes, phylogeny, multilocus sequence types, serotypes, virulence factors, and AMR genes. Of the 29 DEC isolates, 27 were confirmed by WGS and enteropathogenic E. coli (37.0%) and enteroaggregative E. coli (33.3%) were the predominant pathotypes. Isolates exhibited extensive genetic diversity, representing phylogroups A and B1 and 22 serotypes. Phenotypic resistance to β-lactams was common, with 25.9% of isolates carrying bla_CTX-M-15. Virulence profiling identified diverse adhesins, toxins, iron acquisition systems, and type III secretion system components. DEC isolates in Bhutan comprise a genetically diverse population with a concerning convergence of virulence determinants and multidrug resistance. The findings underscore the strengthening of sustained genomic surveillance to monitor AMR and genomic epidemiology of bacterial pathogens. Full article

Plant-pathogenic bacteria threaten crop productivity and quality, yet chemical options remain limited compared with those for fungal and oomycete diseases. Current management relies mainly on copper bactericides, limited antibiotics, induced-resistance agents, biocontrol and resistant cultivars. However, copper and streptomycin resistance, efflux-mediated multidrug tolerance and rapid pathogen adaptation have weakened these strategies. Target-oriented research provides a framework for exploring agricultural antibacterials, anti-virulence agents, anti-colonization strategies, resistance sensitizers and host-resistance interventions, but many of these approaches remain conceptual, model-system, greenhouse or medical-bacteriology-derived rather than proven field solutions. This review classifies bacterial control targets into two interconnected groups: growth-essential targets, including peptidoglycan biosynthesis, membrane/envelope systems, nucleic-acid processes, protein synthesis, metabolism, nutrient transport and cell division; and anti-virulence/anti-adaptation targets, including secretion systems, quorum sensing, biofilms, motility, adhesion, cell-wall-degrading enzymes, tolerance systems, oxidative-stress responses and host susceptibility factors. Using “Candidatus Liberibacter asiaticus” (CLas) as a case study, genome annotation and infection-stage transcript-abundance data prioritized Sec-dependent secretion, outer-membrane/surface proteins, Bam assembly, nutrient transporters, Clp proteostasis, redox adaptation and core cellular processes as candidate target classes. Envelope-associated, secretion/anti-virulence, nutrient-acquisition and stress-sensitization modules may represent potential directions for downstream validation, but CLas candidates remain hypothesis-generating priorities requiring validation for essentiality, conservation, druggability, delivery feasibility, crop safety and field performance. Full article

Salmonella is a globally significant foodborne intracellular pathogen, and invasive salmonellosis poses a major global public health threat. The NLR family CARD-containing protein 4 (NLRC4) inflammasome, a pivotal cytosolic innate immune sensor, specifically recognizes Salmonella flagellin and type III secretion system (T3SS) components via the NAIP (NLR family apoptosis inhibitory protein) family. Upon activation, it triggers pyroptosis, pro-inflammatory cytokine release, and infected intestinal epithelial cell extrusion, serving as a central pathway for host defense against Salmonella colonization and systemic spread. This work systematically summarizes the structural composition, activation mechanisms, post-translational modifications, and regulatory protein network of the NLRC4 inflammasome, and highlights the molecular mechanisms by which Salmonella evades NLRC4 surveillance through multiple strategies: transcriptional downregulation of immunogenic ligands, structural modification of T3SS components, secretion of effector proteins, and chemotaxis-virulence synergy. A comprehensive delineation of the co-evolutionary arms race between Salmonella and the NLRC4 inflammasome provides an integrated mechanistic framework for understanding host–pathogen immune interplay. Deciphering the mechanisms of bacterial immune evasion on this basis holds critical importance for identifying novel anti-infective targets and advancing translational preventive and therapeutic strategies against salmonellosis. Full article

Background: Canine otitis externa is a clinically relevant niche where Pseudomonas aeruginosa may persist under inflammatory, antimicrobial, and biofilm-favoring conditions. This study characterized the virulome and population structure of canine otitis externa-derived P. aeruginosa isolates from Hungary. Methods: Of 110 isolates previously subjected to minimum inhibitory concentration testing, 70 phenotypically selected isolates underwent long-read whole-genome sequencing and were included in virulence-factor analysis. Virulence-associated genes were detected using the Virulence Factor Database with an 80% identity and 80% coverage threshold and were interpreted by functional systems, including motility, adhesion, biofilm formation, secretion systems, siderophores, quorum sensing, secreted enzymes, and type III secretion system effectors. Results: The isolates carried a broad and highly conserved virulence-associated backbone. Genes related to alginate production, type IV pili, flagellar motility, pyochelin, phenazine biosynthesis, Xcp secretion, type VI secretion, and proteolytic enzymes were widely distributed. Type III secretion effector genes were variable: exoT was detected in 68/70 isolates, exoY in 63/70, exoS in 50/70, and exoU in 15/70. MLST indicated a genetically diverse population, and virulome size showed no strong correlation with the modified multiple antimicrobial resistance index. Conclusions: These findings support integrated genomic surveillance of virulence and antimicrobial resistance in canine otitis-associated P. aeruginosa. Full article

Concurrent multiple myeloma (MM) and AL amyloidosis is associated with the poorest outcomes among plasma cell dyscrasias and has dramatically reduced median overall survival. Despite their clinical significance, comprehensive systematic histopathological studies, characterizing multiorgan involvement and lesion severity are remarkably scarce. This study includes 24 autopsies (of 18 women and six men; median age—68 years) with MM-AL. Immunohistochemical (IHC) typing was performed with an expanded antibody panel targeting the amyloid precursor protein; anti-human CD138 antibody was used to identify plasma cells in bone marrow sections. Clinical diagnosis of MM with monoclonal G-lambda secretion, Durie–Salmon Stages II–III, was established in 17 (71%) patients; MM with monoclonal G-kappa secretion, Stage III, in five (21%); and non-secreting MM in two (8%). Systemic amyloidosis was revealed during life in only 15 (62.5%) patients. In all cases, extensive amyloid deposits were observed in the myocardium, lungs and kidneys, establishing the morphological basis for multiorgan failure. IHC typing of amyloids confirmed 18 (75%) cases of AL-lambda amyloidosis and six (25%) of AL-kappa amyloidosis. Our results clarify MM-AL morphogenesis and underscore that AL is frequently underdiagnosed in MM patients. Comprehensive histopathological studies with IHC typing are necessary to confirm the diagnosis, refine the prognosis, and optimize the therapeutic strategies. Full article

Endometriosis is a chronic inflammatory disease in which transforming growth factor-beta (TGF-β) has been implicated in immune dysregulation, extracellular matrix remodeling, and fibrosis. Data on baseline secretion of TGF-β isoforms by systemic immune cells remain limited. This pilot study quantified unstimulated secretion of TGF-β1, TGF-β2, and TGF-β3 by peripheral blood mononuclear cell (PBMC) cultures from women with and without endometriosis and explored stage-related patterns. In this prospective case–control study, PBMCs from 50 women with surgically confirmed endometriosis and 30 controls were cultured for 24 h without exogenous stimulation. Supernatant concentrations were measured using a multiplex bead-based immunoassay (Bio-Plex, Bio-Rad) and expressed as pg/mL; between-group and stage-related differences were assessed using non-parametric tests. Median 24 h secretion was similar between groups (TGF-β1: 103,816 vs. 114,700 pg/mL, p = 0.25; TGF-β2: 3735 vs. 3732 pg/mL, p = 0.32; TGF-β3: 3280 vs. 3284 pg/mL, p = 0.70). Within the endometriosis cohort, TGF-β2 was significantly higher in moderate/advanced disease (rASRM stages III–IV) than in minimal/mild disease (stages I–II), whereas TGF-β1 and TGF-β3 did not reach statistical significance for a stage-dependent pattern in this pilot cohort (p = 0.42 and p = 0.41, respectively; Kruskal–Wallis), and a type II error cannot be excluded given the small sample size per rASRM (revised American Society of Reproductive Medicine)stage (n = 11–14). These findings suggest that TGF-β dysregulation is compartmentalized to the peritoneal environment rather than systemically imprinted in circulating immune cells. The stage-dependent elevation of TGF-β2 supports its role in progressive fibrogenesis and as a candidate severity biomarker, warranting confirmation in larger, stimulus-augmented studies. Full article

Lysobacter antibioticus Hz25 is a novel strain that was isolated from the rhizosphere of the relict endemic plant Hedysarum zundukii Peschkova (Fabaceae), which grows on carbonate soils in the Baikal region of Russia. This work presents the complete genome sequence of Hz25 (5.98 Mb, 66.94% GC), which was obtained using a hybrid assembly method combining Oxford Nanopore and Illumina sequencing. Phylogenetic analysis based on 47 Lysobacter genomes and an average nucleotide identity (ANI) value of 96% confirmed its affiliation with L. antibioticus. A comparative pan-genome analysis with three closely related strains (13-6, 76, and ATCC 29479) identified 554 strain-specific genes. This significant genomic plasticity likely reflects adaptation to the sharply continental climate, high insolation, and low free iron content of the native soil. The genome encodes a comprehensive micropredator arsenal, including: seven chitinase genes (GH18 and GH19 families); bacteriolytic enzymes (Blp, L1, L4, Ami); a complete type III secretion system (T3SS) with predicted effectors; type IV pili (including the PilZ-PilB regulatory complex); and siderophore biosynthesis genes (lysochelin). The genome contains genes ars of an arsenic resistance system, but lacks the ACR3 efflux pump, suggesting that these genes may have alternative functions. Genes involved in calcium homeostasis (Excalibur domain, Na⁺/Ca²⁺ antiporter) were also identified. These features make Hz25 a promising candidate for biocontrol applications in cold climates and metal-contaminated environments. Full article

Background/Objectives: Melioidosis, caused by Burkholderia pseudomallei, is a severe tropical infectious disease associated with high mortality in endemic regions. Early diagnosis remains challenging because conventional diagnostic methods, including culture, serological assays, and molecular techniques, have limitations in sensitivity, specificity, processing time, and accessibility in resource-limited settings. This review evaluates current diagnostic approaches and highlights the potential of short peptide biomarkers for improving melioidosis detection. Methods: A narrative literature review was conducted using four electronic databases (PubMed, Scopus, Web of Science, and Google Scholar) covering publications from 2000 to 2024. Relevant studies were identified using predefined keywords related to melioidosis diagnostics, biomarkers, and peptide-based approaches, and were screened based on relevance to diagnostic methods and peptide biomarker development in Burkholderia pseudomallei. Results: Several biomarkers have been investigated for melioidosis diagnostics, including capsular polysaccharide (CPS), type III secretion system 1 (TTS1), and other virulence-associated proteins such as Hcp1 and BPSS1187. Among these, CPS and TTS1 are highly conserved and specific targets widely used in molecular and antigen-based detection methods. Short peptide epitopes derived from these antigens demonstrate promising advantages over whole proteins, including improved stability, high specificity, easier synthesis, and reduced production costs. Advances in epitope prediction technologies and peptide-based biosensors have further expanded the potential applications of short peptides in rapid diagnostic platforms, including ELISA, lateral flow immunoassays, and biosensor-based detection systems. Conclusions: Short peptide–based biomarkers represent a promising strategy for developing rapid, sensitive, and cost-effective diagnostic tools for melioidosis, particularly in endemic and resource-limited settings. Full article