Microbiology spectrum最新文献

{"title":"Nicotinamide mononucleotide production by non-recombinant <i>Limosilactobacillus <b>reuteri</b></i> and nicotinamide adenine dinucleotide synthesizing lactic acid bacteria.","authors":"Satoru Ozaki, Yoshiko Honme, Masashi Morifuji","doi":"10.1128/spectrum.00333-25","DOIUrl":"https://doi.org/10.1128/spectrum.00333-25","url":null,"abstract":"<p><p>β-nicotinamide mononucleotide (NMN) is a precursor of nicotinamide adenine dinucleotide (NAD⁺) and has the potential to suppress aging. Certain strains of lactic acid bacteria (LAB) can produce cofactors and vitamins through fermentation. Dozens of LAB species are considered to be safe for human ingestion, and some strains act as probiotics, which are live microorganisms that confer health benefits to the host. However, the production of NMN by LAB species, especially non-recombinant strains, has rarely been investigated. The purpose of this study was to identify LAB species that produce NMN and to develop a method to obtain a higher concentration of NMN using LAB. We quantified NMN concentrations in the supernatants of MRS broth cultures of 18 LAB type strains and determined that <i>Limosilactobacillus reuteri</i> JCM 1112^T produced NMN. In this strain, the precursors of NMN were identified as NAD⁺, nicotinic acid, and nicotinamide based on the production of isotope-labeled NMN from these precursors labeled with stable isotopes. <i>L. reuteri</i> ME-989 produced NMN at 16.7 µmol/L by co-cultivation with <i>Lactobacillus johnsonii</i> JCM 2012^T, which has a high NAD⁺-synthesizing ability. Non-recombinant <i>L. reuteri</i> and NAD⁺-synthesizing LAB may be useful for producing safe fermented products containing NMN.</p><p><strong>Importance: </strong>β-nicotinamide mononucleotide (NMN) is a precursor of nicotinamide adenine dinucleotide (NAD⁺) and has the potential to suppress aging. Despite its increasing use in recent years, the production cost of NMN remains high. Certain strains of lactic acid bacteria (LAB), which are widely used in the fermentation of foods and are marketed as probiotics due to their safety and functional benefits, offer a promising alternative for the cost-effective production of functional compounds. However, the production of NMN by non-recombinant LAB has rarely been investigated except for some specific species. Our study has discovered that <i>Limosilactobacillus reuteri</i> produces NMN. The NMN production yield of this species was enhanced through co-cultivation with NAD⁺-synthesizing bacteria. These findings are significant for the development of safe, NMN-enriched fermented products.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0033325"},"PeriodicalIF":3.8,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145329282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pangenome analysis of Tanzanian clinical <i>Klebsiella pneumoniae</i> reveals pandemic clones with high genome plasticity and versatile mobilome, virulome, and resistome profiles.","authors":"Samweli Y Bahati, Reuben S Maghembe","doi":"10.1128/spectrum.01947-25","DOIUrl":"https://doi.org/10.1128/spectrum.01947-25","url":null,"abstract":"<p><p><i>Klebsiella pneumoniae</i> is a rapidly evolving pathogen with a diverse pangenome whose mobilome and resistome remain elusive. Here, we aimed to delineate the pangenome of 198 isolates from Tanzanian regions. Raw Illumina reads retrieved from public repositories were assembled and analyzed using multilocus sequence typing, core-genome single nucleotide polymorphism (SNP)-based phylogeny, and capsular polysaccharide (K-locus) and lipopolysaccharide O-antigen (O-locus) typing. A total of 184 isolates were classified as <i>Klebsiella pneumoniae sensu stricto</i>, while 14 belonged to other species within the <i>Klebsiella pneumoniae</i> complex. We identified 90 sequence types (STs), including global high-risk ST45, ST39, ST336, ST14, ST1552, and ST17. KL24 and KL25 were the most common K-loci, while OL2α.1 and OL2α.2 were dominant O-loci. Pangenome analysis revealed 30,992 gene families, distributed as persistent (13.6%), shell (11.2%), and cloud (75.2%) genes, suggesting an open pangenome structure. Core-genome SNP-based phylogeny confirmed clonal expansion and lineage clustering. Virulence profiling showed yersiniabactin in 44% of isolates. Most genomes carried key fimbrial and iron uptake genes. Resistome analysis revealed near-universal presence of <i>bla_CTX-M-15</i>, <i>oqxA/B</i>, <i>fosA6</i>, <i>sul2</i>, and <i>marA</i>. Plasmid typing identified IncF-type (76%) and Col-type (54%) plasmids, while over 120 mobile genetic elements were detected, whose frequencies were on a huge spectrum of insertion sequences (e.g., IS5075 and MITE<i>Ype1</i>) and transposons (e.g., Tn5403 and Tn6082). Conclusively, Tanzanian <i>K. pneumoniae</i> strains exhibit extensive genomic plasticity, high-risk lineages, and a versatile mobilome, calling for national genomic surveillance to inform intervention strategies.IMPORTANCEThe <i>Klebsiella pneumoniae</i> complex comprises a diverse group of bacterial pathogens adapted to thrive over a wide range of environments. Isolates from clinical and environmental samples are implicated in nosocomial infections and multidrug resistance, with similar genome structures and inherent genes. Our study presents the first pangenome report underlying genomic plasticity of <i>K. pneumoniae</i> isolates from Tanzanian clinical specimens, demonstrating versatile clones, mobilome, and resistome profiles. Combining these profiles with the versatility of K and O structures, our study emphasizes the need for comprehensive multidisciplinary surveillance studies to optimize therapeutic and vaccine development.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0194725"},"PeriodicalIF":3.8,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145329302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two strains of <i>Bacillus velezensis</i>: potent probiotics against <i>Escherichia coli</i> K99-induced diarrhea with high safety in mice.","authors":"Fengjie Wang, Yanan Wang, Hongjun Zhang, Bowei Zhao, Jian Li, Ruili Shi, Li Chen, Zhiqiang Zhang, Qiumei Shi, Qinghui Jia, Tonglei Wu","doi":"10.1128/spectrum.01214-25","DOIUrl":"https://doi.org/10.1128/spectrum.01214-25","url":null,"abstract":"<p><p><i>Escherichia coli</i> K99 is a primary causative agent of diarrhea in young animals, leading to significant health and economic losses. With growing concerns over antibiotic resistance, probiotics-particularly <i>Bacillus</i> species-are gaining attention as effective alternatives for disease prevention and health promotion in livestock. In this study, 39 <i>Bacillus</i> strains were isolated from fresh cattle feces. Preliminary screening focused on biofilm formation, hemolytic activity, and antibacterial effects against <i>E. coli</i> K99. Promising candidates were further evaluated for <i>in vitro</i> probiotic characteristics and safety, including tolerance to acidic and bile salt conditions, heat resistance, hydrophobicity, enzymatic activity, and the presence of virulence and antibiotic resistance genes. <i>In vivo</i> assessments involved acute and subchronic toxicity tests and protective efficacy evaluations in a mouse model challenged with <i>E. coli</i> K99. Four strains-T36, B102, B116, and B150-demonstrated strong biofilm-forming ability, non-hemolytic properties, and notable antimicrobial activity. Among them, B102 and B116 showed excellent probiotic traits and safety profiles <i>in vitro</i>, lacking gelatinase and lecithinase activity, and were free of detectable virulence or resistance genes. <i>In vivo</i>, oral administration of B102 and B116 at high doses caused no acute or subchronic toxicity in mice. Notably, these strains improved the survival rate of <i>E. coli</i> K99-infected mice to 50% and 30%, respectively, compared to 0% in the untreated group. In conclusion, strains B102 and B116 exhibit strong probiotic potential and safety, offering promising alternatives to antibiotics for the prevention and control of <i>E. coli</i> K99 infections in animals. Their application may contribute to sustainable livestock health management.IMPORTANCE<i>Escherichia coli</i> K99-induced diarrhea causes severe economic losses in livestock farming, with limited safe control options due to antibiotic resistance. This study identifies two <i>Bacillus velezensis</i> strains (B102 and B116) that effectively inhibit <i>E. coli</i> K99, enhance survival rates in infected mice, and exhibit strong safety profiles. Their tolerance to gastrointestinal stress and lack of virulence or resistance genes make them ideal antibiotic alternatives. These strains could promote sustainable livestock health by reducing antibiotic use, mitigating resistance risks, and improving disease control, benefiting both agricultural productivity and public health.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0121425"},"PeriodicalIF":3.8,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145329556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dual transcriptomics suggests trophoblastic sequestration and splicing blockade induced by <i>Trypanosoma cruzi</i> during <i>in vitro</i> infection.","authors":"Tatiana M Cáceres, Lissa Cruz-Saavedra, Luz Helena Patiño, Manuel Alfonso Patarroyo, Juan David Ramírez","doi":"10.1128/spectrum.00887-25","DOIUrl":"https://doi.org/10.1128/spectrum.00887-25","url":null,"abstract":"<p><p>Congenital transmission of <i>Trypanosoma cruzi</i> is a significant public health concern, involving complex interactions between the parasite, the placenta, and the fetus. However, the mechanisms facilitating parasite passage across the placental barrier remain incompletely understood. This study explores the transcriptional response of both <i>T. cruzi</i> (TcI) and human trophoblastic cells during <i>in vitro</i> infection, aiming to provide insights into parasite-host interactions relevant to congenital Chagas disease. Two TcI strains (MHOM/CO/01/DA and MHOM/CO/04/MG) were used to infect BeWo cells, and RNA was sequenced at 72 and 120 h post-infection. The MG strain exhibited higher invasion and replication rates than the DA strain. Transcriptomic analysis of the parasite revealed modulation of 157 genes, including several encoding surface-associated multigene families potentially involved in host interaction. In host cells, the upregulation of histones and ribonucleoproteins suggested chromatin remodeling, while the downregulation of RNA splicing-related genes pointed to alterations in RNA processing. At 120 h, genes associated with necroptosis were upregulated, indicating a shift in the host cell response. Overall, these results highlight key molecular changes during trophoblast infection by TcI strains and provide a transcriptomic resource for advancing the understanding of congenital <i>T. cruzi</i> infection.<b>IMPORTANCE</b>Congenital transmission of <i>Trypanosoma cruzi</i>, the causative agent of Chagas disease, remains a significant global health concern. However, the mechanisms by which the parasite crosses the placenta and impacts fetal development are not yet fully understood. This study investigates the interaction between <i>T. cruzi</i> and trophoblastic cells-key components of the placental barrier-by analyzing transcriptomic changes in both the parasite and the host during infection. The findings provide insight into the molecular alterations associated with congenital infection and contribute to a better understanding of the host-parasite dynamics at the maternal-fetal interface. These results offer a valuable resource for advancing research into the biological processes underlying congenital Chagas disease.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0088725"},"PeriodicalIF":3.8,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145329682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Niclosamide nanoparticles as a novel adjuvant reverse colistin resistance via multiple mechanisms against multidrug-resistant <i>Salmonella</i> infections.","authors":"Kaifang Yi, Peiyi Liu, Mengyao Zhang, Qiange Liu, Mengjing Feng, Zibo Li, Dandan He, Li Yuan, Xiaoyuan Ma, Gongzheng Hu","doi":"10.1128/spectrum.02252-25","DOIUrl":"https://doi.org/10.1128/spectrum.02252-25","url":null,"abstract":"<p><p>The mobile colistin resistance (<i>mcr</i>) mechanism enables rapid horizontal transfer of resistance genes across food, animals, and humans, driving significant resistance in <i>mcr</i>-carrying bacteria. While numerous adjuvants can reverse colistin resistance, research on their dose-response relationships remains limited, and most suffer from poor solubility, low bioavailability, and safety issues, hindering clinical use. The dose-response analysis showed that niclosamide could achieve a high reversal efficiency within a relatively low concentration range. However, as the concentration of niclosamide increased, the ability to reverse colistin resistance remained unchanged, and the reversal efficiency gradually decreased. Mechanistic analyses reveal that its synergistic antibacterial effect with colistin involves disrupting bacterial membrane permeability, dissipating proton motive force, and inhibiting efflux pumps, leading to membrane damage, cytoplasmic leakage, ATP depletion, and accelerated reactive oxygen species-mediated oxidative damage, ultimately resulting in the death of bacterial cells. A niclosamide nanodelivery system (niclosamide-loaded mPEG-PLGA nanoparticles [NCL@mPEG-PLGA-NPs]) was developed to enhance bioavailability, significantly boosting colistin's efficacy against <i>Salmonella in vitro</i> and <i>in vivo</i>. The in-depth study of the dose-response relationship of adjuvants in reversing colistin resistance and the establishment of the niclosamide nanodrug delivery system will lay a scientific foundation for the clinical application of colistin adjuvants and the development of suitable drug delivery systems.</p><p><strong>Importance: </strong>Colistin is used as a last resort for many infections caused by multidrug-resistant gram-negative bacteria, but colistin-resistant strains are on the rise. Studies have found that the combination of niclosamide and colistin exhibits significant synergistic antibacterial effects. Dose-response analysis shows that niclosamide has extremely high resistance reversal efficiency within a relatively low concentration range. The development of the new dosage form of NCL@mPEG-PLGA-NPs will lay a scientific foundation for the clinical application of colistin adjuvants and the development of drug delivery systems.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0225225"},"PeriodicalIF":3.8,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145329296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal dynamics and environmental controls of planktonic archaea in a typical subtropical estuary.","authors":"Wenya Wei, Penghui Li, Fahui Gong, Cheng Zhang, Kedong Yin, Wei Xie","doi":"10.1128/spectrum.00759-25","DOIUrl":"https://doi.org/10.1128/spectrum.00759-25","url":null,"abstract":"<p><p>Planktonic archaea are pivotal in the biogeochemical cycling across estuaries to coastal seas. A thorough comprehension of their adaptive mechanisms to seasonal environmental fluctuations remains largely unexplored. This study investigates the seasonal dynamics of planktonic archaeal communities and their responses to the biotic and abiotic factors in the Pearl River Estuary (PRE). Thermoproteota and Thermoplasmatota are the two most abundant phyla, and both show a significant difference between summer and winter. As phosphorus is the most limiting nutrient in the PRE, PO₄^3- is found to have the most significant seasonal variation in random forest, followed by temperature and Chl a. The Mantel test for the abundant archaea showed that the number of phosphate-correlated OTUs was the second highest, following only temperature. The generalized additive modeling (GAM) analysis further reveals that the abundance of Thermoproteota was controlled by PO₄^3-, temperature, and DO, whereas MGII was controlled by PO₄^3-, pH, salinity, and Chl a. Our research demonstrates that there is a strong seasonality in coastal archaeal communities and sheds light on revealing their environmental adaptation and predicting biogeochemical function alterations in response to regional and global environmental changes.</p><p><strong>Importance: </strong>Archaea not only sustain the equilibrium of elemental cycles but also exhibit remarkable plasticity in responding to and adapting to fluctuating environmental conditions. In particular, the adaptive strategies and ecological impacts of archaea in complex and dynamic settings, such as estuaries, represent a compelling yet unresolved area of scientific inquiry. Our study focused on the seasonal dynamics of planktonic archaeal communities in the Pearl River Estuary (PRE) and their response to biotic and abiotic factors. Our study demonstrates a strong seasonality in the aggregation of these coastal archaeal communities and adaptability to dynamic phosphate concentrations, emphasizing the critical role of phosphate in controlling the distribution of archaea. Our study sheds light on revealing environmental adaptation and predicting biogeochemical function alterations in response to regional and global environmental changes.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0075925"},"PeriodicalIF":3.8,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145329403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genomic insights and functional adaptation of <i>Mycobacterium intracellulare</i> strains isolated from patients with inflammatory bowel disease.","authors":"Sushanta Deb, Lata Kumari, Neeraj Mahajan, Shiv K Basant, Twinkle Joshi, Vineet Ahuja, Urvashi B Singh","doi":"10.1128/spectrum.03414-24","DOIUrl":"https://doi.org/10.1128/spectrum.03414-24","url":null,"abstract":"<p><p>In clinical practice, inappropriate diagnosis of inflammatory bowel disease (IBD) ascribing the disease to <i>Mycobacterium avium paratuberculosis</i> (MAP) and resulting mistreatment has been a challenge for healthcare workers. This highlights the need to accurately identify and characterize MAP members in patients with gastrointestinal (GI) ulceration. A total of 889 patients exhibiting symptoms of IBD were examined for MAP infection. While MAP was not recovered from any of the specimens, we successfully isolated and sequenced four clinically relevant <i>Mycobacterium intracellulare</i> genomes from GI samples of patients diagnosed with IBD. In-depth phylogenomic and comparative genomics demonstrated genomic heterogeneity and variable metabolic profile in <i>M. intracellulare</i> species. Analysis of four isolate genomes disclosed an ongoing genome reduction process, which might be crucial for adaptation and increased virulence of intestinal <i>M. intracellulare</i> strains. Findings provide insights into the narrow-spectrum resistance to antibiotics, metabolic adaptation, and potential virulence of <i>M. intracellulare</i> strains, particularly those associated with human infections. Recombination analysis revealed minimal recombination and higher mutational divergence, which indicate evolutionary constraints leading to clonal evolution of <i>M. intracellulare</i> species.</p><p><strong>Importance: </strong>The present study provides valuable insights on genomic diversity, metabolic adaptability, and virulence of <i>Mycobacterium intracellulare</i> strains infecting human host. Our findings highlight the need for additional research on essential genes as potential drug targets. An updated knowledge on intestinal <i>M. intracellulare</i> strains regarding its genomic characteristics and evolutionary processes is critical to design better diagnostic and treatment approaches for intestinal infections.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0341424"},"PeriodicalIF":3.8,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145329655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sublethal interaction factor (SIF), a growth-based method to analyze antibiotic combinations at sub-inhibitory concentrations.","authors":"D L Sánchez-Hevia, N Fatsis-Kavalopoulos, D I Andersson","doi":"10.1128/spectrum.01070-25","DOIUrl":"https://doi.org/10.1128/spectrum.01070-25","url":null,"abstract":"<p><p>Antibiotic resistance is a global concern with significant implications for healthcare, food production, and the environment. Therapies involving antibiotic combinations are frequently employed as a strategy to overcome antibiotic resistance. When present in combination, the efficacy of antibiotics may be enhanced or weakened, and as antibiotic interactions are <i>a priori</i> generally unpredictable, they need to be experimentally determined. Though antibiotics are regularly present at sublethal concentrations (e.g., in patients with suboptimal dosing regimens, late after the last dosage, difficult-to-penetrate tissues, and also in the natural environment), effects of antibiotic combinations are generally studied at lethal dosages. To address this, we developed the sublethal interaction factor (SIF) assay, based on the Bliss independence model, to quantify antibiotic combination effects at sublethal concentrations. SIF assay uses the whole growth curve, instead of only the growth rate, and determines reliably the outcome of the interaction between two antibiotics at sublethal concentrations. The SIF method was validated against the CombiANT assay and showed high sensitivity and specificity, attesting to its usability.IMPORTANCESublethal interaction factor (SIF), a method herein proposed, simplifies the analysis of antibiotic interactions at sub-inhibitory concentrations and shows a high correlation with the fractional inhibitory concentration index (FICi), the gold-standard measure used to classify antibiotic interactions when tested at lethal concentrations. The SIF can be easily incorporated into laboratories and has great potential for studying not only antibiotic combinations but also drug interactions and phage therapy.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0107025"},"PeriodicalIF":3.8,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145329527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The adaptive growth and mechanisms of <i>Klebsiella pneumoniae</i> under sucrose and glucose exposure.","authors":"Yunhui He, Fangfang Liu, Congcong Li, Jiayan Wu, Kewei Fan, Zewen Wen, Duoyun Li, Zhijian Yu, Tieying Hou","doi":"10.1128/spectrum.01603-25","DOIUrl":"https://doi.org/10.1128/spectrum.01603-25","url":null,"abstract":"<p><p><i>Klebsiella pneumoniae</i> commonly colonizes the gastrointestinal (GI) mucosa of animals and healthy humans. Successful GI colonization by <i>K. pneumoniae</i> requires overcoming the colonization resistance (CR) exerted by the gut microbiota. Although previous studies have demonstrated the role of microbial carbohydrate metabolism in <i>K. pneumoniae</i> colonization, the specific effects of individual carbohydrates, such as glucose and sucrose, particularly across concentration gradients or under sustained induction on the adaptive growth of <i>K. pneumoniae</i> remain unknown. Herein, we demonstrate that 4% or 8% glucose and sucrose are favorable for promoting adaptive growth of sugar-induced strains. Additionally, the growth response to glucose exhibited strain-specific variability. Sustained sugar induction did not significantly alter the hypermucoviscosity (HMV) phenotype but did affect antibiotic resistance of <i>K. pneumoniae</i>. Knockout of the <i>scrA</i> and <i>scrY</i> genes impaired the adaptive growth under sucrose and glucose conditions, yet did not significantly influence antimicrobial susceptibility or the HMV phenotype. These findings provide insights into the metabolic regulation of <i>K. pneumoniae</i> colonization and offer potential guidance for clinical treatment strategies targeting <i>K. pneumoniae</i>-associated infections.</p><p><strong>Importance: </strong>This work elucidates the impact of single-carbon source gradients and sustained sugar induction on the adaptive growth and drug resistance of <i>Klebsiella pneumoniae</i> and preliminarily reveals the roles of <i>scrA</i> and <i>scrY</i> in carbohydrate metabolism, suggesting a possible mechanism by which sucrose and glucose affect the adaptive growth of <i>K. pneumoniae</i>. These findings contribute to the theoretical understanding of CCR and provide insights that may inform clinical management of <i>K. pneumoniae</i>-related infections.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0160325"},"PeriodicalIF":3.8,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145301933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative analysis of vancomycin-resistant enterococci in colonization and infection-a longitudinal study.","authors":"Vera Blaschke, Vera Rauschenberger, Heike Claus, Stefanie Kampmeier","doi":"10.1128/spectrum.01750-25","DOIUrl":"https://doi.org/10.1128/spectrum.01750-25","url":null,"abstract":"<p><p>Vancomycin-resistant <i>Enterococcus faecium</i> (VREfm) carriage in the gastrointestinal tract is a risk factor for the development of an invasive infection. The exact mechanisms underlying the transition from colonization to infection are still unclear. We conducted a longitudinal study, including 54 paired VREfm isolates, consisting of a colonization and a subsequent bloodstream isolate from the same patient. We performed whole-genome sequencing, biofilm formation assays, and spot-on-lawn assays to investigate genotypic and phenotypic characteristics of the isolates. No significant differences in these characteristics between paired colonization and infection isolates were detected. Genotyping revealed that colonization isolates were genetically closely related to their respective infection isolates in 22 of 27 (81%) isolate pairs. Further studies focusing on the interaction between host epithelium and pathogen are needed to gain more insight into the transition from colonization to infection.IMPORTANC<b>E</b>Previous studies have primarily focused on patient-related risk factors associated with the development of vancomycin-resistant <i>Enterococcus faecium</i> (VREfm) infection. However, identifying and characterizing the bacterial factors responsible for this transition is crucial, especially given the limited treatment options for VREfm infection. Our analyses revealed no significant differences between colonization and infection isolates, suggesting that host-pathogen interaction may play a more critical role in this progression and should be further investigated. Moreover, our findings highlight the importance of risk assessment and infection prevention measures to prevent VREfm colonization as a critical step in the development of VREfm infection.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0175025"},"PeriodicalIF":3.8,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145301913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}