Search Results (2,768)

Ticks are important arthropod vectors that transmit various pathogens to humans, livestock, and wildlife, thereby contributing significantly to the global burden of vector-borne diseases. The tick microbiome, consisting of bacteria, viruses, protozoa, and other microorganisms, plays a crucial role in pathogen transmission dynamics and the emergence of new zoonotic diseases. This review examines the characteristics of tick vectors, the composition and dynamics of tick-associated microbiomes, and their implications for zoonotic disease transmission. We analyze current knowledge of tick-borne pathogens, including Borrelia burgdorferi sensu lato, Rickettsia species, Anaplasma species, and Coxiella species, and highlight the potential for microbiome constituents to serve as reservoirs for emerging pathogens. The complex interactions between tick hosts, their microbiomes, and vertebrate hosts create opportunities for pathogen evolution and interspecies transmission. Recent advances in molecular techniques have revealed previously unknown microbial diversity within tick populations, suggesting that many potential zoonotic pathogens remain undiscovered. We discuss future research directions, including field screening methodologies for pathogen detection, microbiome-based risk assessment approaches, and the development of novel prevention strategies, including tick vaccines. Full article

Upper respiratory tract infections (URTI) are highly prevalent worldwide. Although probiotics have shown potential in preventing URTI, evidence in healthy adults remains limited. Lacticaseibacillus rhamnosus CRL 1505 is a strain with immunomodulatory effects in preclinical studies and benefits in healthy children. Based on this evidence, a randomized, double-blind, placebo-controlled, parallel-group clinical trial was conducted in healthy adults, receiving either L. rhamnosus CRL 1505 (1 bln/day) or placebo for 12 weeks, with a 4-week follow-up. The primary endpoint was the proportion of participants experiencing URTI episodes (at least one, two, or three episode(s)). The secondary endpoints included: number and duration of URTI episodes, URTI-free time, symptom severity, use of symptomatic medication, salivary IgA levels, and safety outcomes. Results show that L. rhamnosus CRL 1505 significantly reduced the number of participants experiencing ≥3 URTI episodes at 16 weeks compared with placebo. The probiotic group experienced fewer URTI episodes per participant, a shorter cumulative duration of URTIs, and a higher URTI-free time rate. Probiotic supplementation significantly reduced the use of symptomatic medications. In conclusion, daily supplementation with L. rhamnosus CRL 1505 reduced the burden of URTI in healthy adults, specifically of those experiencing more episodes, by decreasing infection frequency, duration, and medication use. Full article

Facklamia species are Gram-positive, catalase-negative cocci within the family Aerococcaceae. Historically misidentified as streptococci or enterococci due to phenotypic similarity and conventional biochemical testing limitations, their clinical significance remains incompletely defined. This narrative review synthesizes the current literature on the microbiology, epidemiology, clinical manifestations, diagnostic challenges, and antimicrobial susceptibilities of Facklamia infections, with emphasis on urogynecologic relevance. A structured literature search identified peer-reviewed reports of microbiologically confirmed human infection published through December 2025. These reports indicate global distribution and a broad clinical spectrum. Invasive infections were reported most often in older adults and individuals with structural abnormalities, chronic comorbidities, or recent surgical interventions; however, cases in otherwise healthy patients are described. Emerging microbiome data suggest that F. hominis may be enriched in adult females with lower urinary tract symptoms, supporting the possibility that the female urogenital tract functions as a potential reservoir and site of pathogenic activity. Antimicrobial susceptibility patterns vary, with documented resistance to penicillin, macrolides, clindamycin, and tetracyclines, and susceptibility to cephalosporins, vancomycin, and linezolid. Overall, Facklamia species should be recognized as underdiagnosed opportunistic pathogens with both invasive and urogynecologic relevance. Increased awareness, improved diagnostic identification, and systematic susceptibility profiling are needed to clarify their pathogenic role and guide appropriate antimicrobial therapy. Full article

The gut microbiome plays a pivotal role in modulating multiple physiological processes from the earliest stages of life. However, the complete scope of its effects during childhood is yet to be fully elucidated, which underscores the importance of enhancing the understanding of this emerging area of research. This narrative review provides an overview of the influence of the gut microbiome in early human ontogeny by examining its role in brain and immune development, as well as its involvement in neurodevelopmental disorders and early-life mental health. The gut microbiome contributes to shaping the development and function of both the brain and the immune system. Its influence appears to be primarily mediated through the synthesis of neurotransmitters and microbial metabolites, as well as through the activation of specific pathways within the hypothalamic–pituitary–adrenal axis. Nevertheless, the exact mechanisms through which the gut microbiome exerts these effects, and the full extent of its impact on neurodevelopmental and immune health, remain incompletely understood and continue to be active areas of research and scientific debate. Ultimately, advances revealing how the gut microbiome shapes early brain and immune system development will create new opportunities for innovative interventions and predictive strategies aimed at transforming pediatric health outcomes. Full article

Acne vulgaris is a prevalent inflammatory disorder of the pilosebaceous unit involving follicular hyperkeratinization, altered sebum production, Cutibacterium acnes proliferation, microbiome imbalance, and immune activation. Although antibiotics, retinoids, benzoyl peroxide, and keratolytic agents remain central to clinical management, their long-term use may be limited by irritation, recurrence, adherence issues, and increasing antimicrobial resistance. This narrative review critically evaluates the dermatological relevance of Melaleuca alternifolia tea tree essential oil (TTEO), Mentha piperita peppermint essential oil (PPEO), and polyhydroxy acids (PHAs), as well as their incorporation into biopolymeric delivery systems for acne-oriented topical applications. Following SANRA principles, evidence from clinical, preclinical, ex vivo, and in vitro studies was synthesized, with emphasis on antimicrobial activity, inflammatory modulation, keratolytic and barrier-supportive effects, formulation stability, and release behavior. TTEO shows the strongest clinical support among the reviewed natural bioactives, including reductions in lesion counts and acne severity when applied as conventional or nanoemulsion-based formulations. PPEO is mainly supported by experimental evidence, particularly antimicrobial activity against acne-associated microorganisms, anti-inflammatory potential, and menthol-related neurocutaneous effects, whereas acne-specific clinical validation remains limited. PHAs, particularly gluconolactone, are better supported for barrier improvement, hydration, tolerability, and seboregulation than for direct acne lesion reduction. Hydrogels, electrospun nanofibers, polymeric films, nanoencapsulation systems, and controlled-release platforms may improve local retention, protect volatile or irritation-prone compounds, and modulate active release at the skin surface. However, most biopolymeric platforms still rely on early-stage or indirect dermatological evidence. Overall, biopolymeric delivery systems offer a rational formulation strategy to improve the stability, tolerability, and localized action of selected acne-relevant bioactives, but their clinical translation requires standardized composition, reproducible fabrication, skin-relevant release assays, safety assessment, and controlled human studies. Full article

Human milk is widely recognised as the optimal source of nutrition for newborns and infants, providing not only an ideal macronutrient composition but also a range of bioactive components that exert important non-nutritional functions, and as such it represents the first functional food consumed in early life. Among these bioactive components, the human milk oligosaccharides (HMOs)—a structurally diverse family of glycans present in human milk at concentrations 100- to 1000-fold higher than in the milk of other mammalian species—have emerged as multifunctional contributors to the establishment of the intestinal microbiome, immune development, anti-infective defence, and epithelial barrier integrity during a developmental window characterised by immune immaturity. The aim of the present narrative review is to synthesise current evidence on the anti-infective properties of HMOs in infancy and to integrate, within a single framework, five interconnected mechanisms through which HMOs protect the infant against infection: glycan-mimicry-based competitive inhibition of pathogen adhesion, direct antimicrobial and antibiofilm activity, selective prebiotic shaping of the gut microbiome, modulation of innate and adaptive immune responses, and reinforcement of mucosal barrier integrity in the gut and lungs. Breastfeeding constitutes a natural strategy for anti-infective protection in early childhood, while infant formulas supplemented with biotechnologically produced HMOs that are structurally identical to those in human milk provide measurable benefits for non-breastfed infants. Full article

Cervicovaginal dysbiosis is an established co-factor of high-risk human papillomavirus (HPV) persistence and cervical neoplastic development, yet most studies address the bacterial compartment in isolation, leaving fungal communities and bacterial–fungal cross-kingdom interactions underexplored, particularly in Central Asian populations. We performed shotgun metagenomic sequencing (mNGS) of cervicovaginal samples from 311 Kazakhstani women undergoing routine cervical screening. HPV status was determined using combined PCR and mNGS methods, and cervical screening was completed using liquid-based cytology (NILM, ASC-US, LSIL, ASC-H). Bacterial, viral, and fungal taxa were profiled from a single shotgun dataset with Kraken2 pipeline. Bacterial community state types (CSTs) were determined based on dominant bacterial species, functional gene content was annotated against KEGG using eggNOG, and covariate-adjusted associations were estimated using MaAsLin3. Mycobiome β-diversity differed significantly by HPV status (p = 0.003). In particular, Candida positivity was significantly associated with HPV presence and with high-risk α-9 HPV in cytologically normal (NILM) samples (OR = 3.6, [1.6–9.6], p ≤ 0.001). Covariate-adjusted analysis was consistent with this positive association (q < 0.05). Concurrently, among CSTs, Lactobacillus iners-dominated CST III and dysbiotic Gardnerella vaginalis-dominated CST IV showed a 3-fold higher Candida albicans prevalence (p < 0.01). Further analysis demonstrated that, functionally, both of these CSTs had depleted capacity for lactate metabolism (ko00620, p < 0.0001) and, in particular, for the genetic capacity for pyruvate-dependent H₂O₂ generation (half that of the L. crispatus-dominated CST I). These findings support L. iners as a metabolically permissive rather than protective Lactobacillus and suggest cross-kingdom functional signatures as candidate biomarkers for HPV acquisition and persistence in Central Asia, a region previously absent from the cervicovaginal microbiome literature. Full article

Folate (vitamin B9) is central to one-carbon metabolism, supporting nucleotide biosynthesis, methylation homeostasis, and epigenetic regulation. The gut microbiome both produces and consumes folate, creating a bidirectional axis influencing host health and disease. We systematically reviewed 159 original studies from MEDLINE, Google Scholar, Embase, and Scopus (inception through January 2026) examining enteric microbiota–folate interactions, with intervention evidence graded using the Oxford Centre for Evidence-Based Medicine 2011 framework. Only a minority of gut bacteria possess complete folate biosynthetic pathways; most depend on cross-feeding from prototrophic taxa including Bifidobacterium, Lactobacillus, and Streptococcus. Altered microbial folate metabolism was associated with metabolic, gastrointestinal, oncologic, neuropsychiatric, cardiovascular, immunologic, and reproductive disorders through convergent mechanisms of disrupted methylation, genomic instability, and immune dysregulation. Probiotic interventions achieved the strongest evidence, supported by multiple human controlled and observational trials and animal models. The evidence for prebiotic, dietary, and folate supplementation interventions was moderate due to the predominant animal models and in vitro data. Overall, the predominant associational and observational evidence base is insufficient to establish causal relationships, underscoring the need for adequately powered human randomized controlled trials with folate-specific endpoints, multi-omics integration, and precision approaches matching folate form and dose to individual microbiome and host genetic profiles. Full article

Background: Human hospitals and veterinary centres are hotspots for resistant microbes and plasmids, and metagenomic sequencing offers an agnostic insight into microbiomes, resistomes, and mobilomes, informing strategies for reducing AMR spread. Methods: Environmental samples, including wastewater and surface swabs, were taken from a tertiary human hospital ward (36 samples) and a companion animal veterinary hospital (48 samples) in London. Whole DNA was extracted and metagenomic sequencing undertaken using Oxford Nanopore Technologies’ MinION. Data were analyzed for microbiomes, resistomes and mobilomes and compared. Results: Microbial diversity analyses highlight higher richness across human hospital (HH) environmental samples, but more evenness in veterinary hospital (VH) environmental samples. Diversity showed distinct microbial communities in the HH and VH samples. There were significantly more total antimicrobial resistance gene (ARG) types (p < 0.0001) in the environmental HH samples compared with the environmental VH samples. There was a significantly higher mean number of Enterobacteriales plasmid types (p ≤ 0.0001) in the HH samples. There were significantly more total Gram-Positive plasmid types (p ≤ 0.0001) in the VH samples. Discussion: This research highlights the presence of human and animal pathogens, ARGs and mobile genetic elements in clinical environments, underscoring the importance of multisectoral surveillance. Integrating taxonomic, resistome, and mobilome analyses provides a better understanding of the potential for AMR dissemination at the human–animal–environment interface. This provides insights relevant for the development of targeted surveillance and mitigation strategies within a OH framework. Full article

Fungal β-1,3-glucans are structurally conserved polysaccharide components of the fungal cell wall that exhibit potent immunomodulatory activity. These molecules are recognized by pattern recognition receptors, Toll-like receptors, complement receptor 3, lactosylceramide, scavenger receptors, and EphA2. Binding of β-1,3-glucans through these receptors triggers coordinated innate and adaptive immune responses such as cytokine production, phagocytosis, and trained immunity. In addition to receptor-mediated immune activation, dietary β-1,3-glucans function as fermentable prebiotic fibers that modulate gut microbiota composition, increase short-chain fatty acid production, and strengthen epithelial barrier integrity. These combined immunological and microbiome-mediated effects position β-1,3-glucans as key regulators of gut homeostasis. Preclinical and emerging clinical evidence supports broad therapeutic potential across multiple disease domains, including inflammatory bowel disease, metabolic disorders, respiratory infections, and cancer. In oncology, β-1,3-glucans enhance anti-tumor immunity, improve responses to monoclonal antibodies and chemotherapy, and serve as promising adjuvants in vaccine-based strategies. Additionally, β-1,3-glucan is widely used as a biomarker for invasive fungal infections and represents a validated target of antifungal therapies such as echinocandins. Despite these advances, clinical translation remains limited by heterogeneity in glucan source, structure, and formulation, as well as a lack of appropriately powered, standardized human clinical trials. Future efforts should focus on clarifying mechanisms of action, as well as rigorous clinical evaluation, to fully define the therapeutic utility of fungal β-1,3-glucans. Full article

Microplastics (MPs) are increasingly detected environmental contaminants in both marine and freshwater ecosystems, with reported concentrations ranging from a few to thousands of particles per cubic meter depending on location and methodology. Although growing evidence suggests potential risks to aquatic organisms, the extent of their ecological and biological impacts is still under active investigation. Their size, persistence and capacity to transport chemical additives and co-contaminants allow them to enter biological systems by ingestion and respiration. When ingested, MPs cause oxidative stress, inflammation, and metabolic disorders, resulting in the destruction of vital tissues in major body organs including liver, gills, intestines, and brain. They also change gene expression, cause endocrine and immune pathway perturbation, induce apoptosis, and cause gut microbiome dysbiosis, all of which worsen the health and survival of the organism. MPs also serve as vectors of heavy metals, antibiotics, pesticides, and pathogens and enhance toxicity due to the Trojan horse effect and enable bioaccumulation in food webs. Due to their widespread presence in water, soil, air, and food, MP pollution has direct effects on human, animal, and ecosystem health. This review synthesizes current knowledge on the sources of MPs, the mode of exposure, and the mechanism of toxicity and new ecological implications. It also presents mitigation measures, and stresses a One Health paradigm as the key to taking concerted action on the international level to minimize MP pollution and protect both the environment and human health. Full article

Persistence of human papillomavirus (HPV) infection leading to cervical carcinogenesis can be attributed to the action of high-risk HPVs, but there are still some unclear factors involved in the mechanisms of either viral clearance or persistence. Although many infections may be self-limiting and cleared successfully by the immune response of the infected individuals, other infections result in persistent HPV infection. Recent studies indicate that microbiota in the gut and cervicovaginal tract modulate host immune status, mucosal inflammation, and epithelial barrier integrity. All these factors determine susceptibility to persistent infection. Inflammation, overproduction of reactive oxygen species (ROS), genomic instability, and impaired antiviral transcription pathways are associated with dysbiosis. In parallel, redox imbalance contributes to mitochondrial dysfunction, impairing mitochondrial antiviral signaling (MAVS)-dependent interferon responses and attenuating induction of interferon-stimulated genes. Additionally, extracellular vesicles (EVs) further promote immune evasion, metabolic programming, and epigenetic regulation by facilitating the intercellular exchange of viral constituents, microRNAs, and signaling molecules. Through this interconnected network of mechanisms, microbial dysbiosis, mitochondrial disruption, and EV signaling collectively shape a niche conducive to persistence. Unlike previous reviews that primarily examine microbiome alterations, oxidative stress (OS), mitochondrial dysfunction, extracellular vesicles, or immune responses as separate processes, this review integrates clinical and omics findings into a systems-based conceptual framework of HPV persistence. By emphasizing the potential interactions among these interconnected biological systems, we aim to identify points of biological convergence, generate mechanistic hypotheses, and highlight opportunities for future biomarker development and therapeutic intervention. Full article

The human gut microbiome comprises a diverse community of bacteria whose interactions with the host range from beneficial mutualism to opportunistic pathogenicity. These interactions are shaped by genomic plasticity and ecological pressures that influence whether microbes support host health, remain conditionally harmless, or contribute to disease. Understanding the mechanisms underlying these shifts is essential for clarifying the balance between cooperation and pathogenicity within the gut ecosystem. This review explores the genomic and evolutionary mechanisms that shape microbial adaptation across the mutualism–pathogenicity spectrum in the human gut. Key processes, including horizontal gene transfer (HGT), host-mediated selection, and niche specialization, enable microbes to acquire, regulate, or retain traits that influence colonization, metabolic function, and virulence. These adaptive mechanisms allow gut bacteria to respond dynamically to ecological pressures such as inflammation, antibiotic exposure, and dietary change, resulting in context-dependent microbial behaviors. The review also considers how concepts from insect endosymbiosis may provide insight into gut microbial adaptation. While both systems exhibit host specialization, major differences in transmission mode, ecological flexibility, and genome evolution limit direct comparisons. Rather than following a fixed progression toward parasitism, gut microbes exhibit flexible adaptive strategies shaped by host and environmental conditions. By integrating ecological and evolutionary perspectives, this review presents a balanced framework for understanding how genomic adaptation influences microbial behavior in the gut. This perspective improves our understanding of dysbiosis and microbial pathogenesis and may support the development of microbiome-informed therapeutic strategies for maintaining host health. Full article

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a highly prevalent liver-centred manifestation of systemic metabolic dysfunction. The gut–liver axis provides a biologically credible therapeutic rationale because intestinal dysbiosis, impaired barrier integrity, microbial metabolites, bile acid signalling, short-chain fatty acids, and trimethylamine N-oxide may influence hepatic steatosis, inflammation, and fibrogenesis. This narrative review critically evaluates dietary patterns, prebiotics, probiotics, synbiotics, postbiotics, and fecal microbiota transplantation (FMT) as microbiome-directed strategies in MASLD. The comparative framework prioritises disease-specific human evidence, clinically meaningful endpoints, trial duration and sample size, reproducibility, safety, and feasibility. Dietary optimisation remains the most clinically grounded intervention, whereas probiotics and synbiotics show modest and heterogeneous signals on biochemical or metabolic surrogate endpoints. Prebiotics are mechanistically coherent but supported by limited liver-centred trials. Postbiotics and microbiome-mediated bioactives remain early-stage and require stricter definitional boundaries. FMT is investigational and should not be extrapolated from its established role in recurrent Clostridioides difficile infection. Most available evidence across all intervention categories relies principally on surrogate endpoints—including aminotransferases, insulin resistance indices, lipid parameters, and microbiome compositional shifts—rather than on validated liver-centred outcomes such as histological improvement or quantitative liver fat assessment; this constrains the strength of conclusions that can currently be drawn. Across all categories, microbiome modulation does not by itself establish liver disease modification, and no microbiome-targeted nutritional intervention has yet demonstrated histological benefit in MASLD. Future trials in this field should prioritise validated hepatic endpoints, phenotype-stratified patient enrolment, adequate follow-up duration, and direct comparisons between intervention categories to determine which microbiome-directed strategies, if any, deliver measurable and reproducible hepatic benefit beyond surrogate markers. Full article

γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the central nervous system (CNS) and plays a vital role in maintaining neural balance, regulating mood, and reducing stress responses. Recent metagenomic studies of the gut microbiome have shown that various bacterial species, especially those in the genera Lactobacillus, Bifidobacterium, and Bacteroides, isolated from the human gut and environmental sources such as fermented foods, contain glutamate decarboxylase (GAD) systems that enable GABA production. Microbially produced GABA can influence the microbiota–gut–brain (MGB) axis by activating neural, endocrine, and immune signalling pathways that are crucial for maintaining gut and brain homeostasis. Emerging evidence suggests that supplementation with GABA-producing bacteria, known as psychobiotics, may improve neurotransmitter balance, modulate cytokine production, strengthen the integrity of the intestinal barrier, and alleviate anxiety- and depression-related behaviours. This review summarises current knowledge of GABA-producing bacterial strains derived from the human gut and food environments and explores their potential as emerging psychobiotics in modulating gut–brain communication and mental health. Full article