Search Results (108)

The widespread use of antibiotic growth promoters (AGPs) in livestock production has contributed to the emergence of antimicrobial resistance (AMR) in pathogens. Furthermore, improper dosing and insufficient withdrawal periods lead to the presence of antibiotic residues in meat, posing significant risks to human health. Consequently, regulatory bans on AGP use in poultry and livestock have increased the susceptibility of poultry to previously controlled infectious diseases, highlighting the need for effective and safe alternatives. Postbiotics, defined as preparations of inanimate microorganisms and/or their components that confer a health benefit on the host, have emerged as one of the promising AGP alternatives. Some postbiotic preparations exert immunomodulatory, antioxidant, antimicrobial, and anti-inflammatory effects, modulate gut microbiota, and reduce enteric pathogen loads, leading to improved growth performance, health status, and resilience against heat stress, thereby supporting their role in sustainable poultry production. This review summarizes the current understanding of the effects of postbiotics on poultry health and zootechnical performance and their mechanisms of action, explicitly distinguishing empirical findings demonstrated in poultry from those extrapolated from mammalian or in vitro models. Finally, it outlines knowledge gaps in the biochemical processing and standardization of postbiotics, along with future research priorities for their use as an AGP alternative. Full article

Maintaining gut microbial homeostasis is crucial for host health, whereas infection with Escherichia coli (E. coli) is a major contributor to intestinal inflammation and microbial dysbiosis. Recent research has focused on probiotic strategies for managing enteric inflammatory disorders. Previous studies have shown that beneficial microorganisms show protection through modulating host immune responses, enhancing intestinal epithelial barrier integrity, and inhibiting pathogenic bacteria. To evaluate the prophylactic effectiveness of a recently isolated strain, Lacticaseibacillus casei 2S-1, in a murine model of E. coli-induced enteritis, this study focuses on interactions within the microbiota–intestinal–immune axis, together with host transcriptional responses and pathway enrichment associated with oxidative stress and mitochondrial function. In vitro analysis of probiotic features, including growth dynamics, acidogenic capacity, and tolerance to acidic and bile salt environments, as well as genetic safety profiling, followed the methodical isolation and taxonomic identification of L. casei 2S-1. A preventive intervention protocol was established, and a murine model of enteritis was induced by exposure to E. coli. Histopathological analyses were performed to observe in vivo safety and protective efficacy. Changes in gut microbial structure were characterized by 16S rRNA gene sequencing, while host responses were identified by intestinal immunohistochemistry and transcriptome profiling. L. casei 2S-1 showed probiotic properties. In vitro analyses showed that the strain exhibited tolerance to acidic and bile salt conditions, and its untreated culture supernatant showed antimicrobial activity against pathogenic bacteria. Its safety profile was supported by genomic analysis, which verified the lack of virulence-associated genes and antibiotic resistance factors. In vivo, L. casei 2S-1 pretreatment reduced mortality and intestinal inflammation, modulated gut microbial composition, and preserved intestinal barrier-associated protein expression in infected mice. This study provides experimental evidence supporting the prophylactic effects of L. casei 2S-1 and its associations with gut microbiota modulation and host transcriptional responses, providing a foundation for further investigation of probiotic-based preventive strategies against intestinal infections. Full article

Major histocompatibility complex class II (MHC-II) expression by intestinal epithelial cells (IECs) has emerged as a critical mechanism regulating mucosal immune homeostasis at the interface between the intestinal microbiota, epithelial barrier, and immune system. Beyond professional antigen-presenting cells, IEC-intrinsic MHC-II shapes CD4⁺ T-cell responses, influencing tolerance to commensal microorganisms, immunity to enteric pathogens, and maintenance of barrier integrity. Recent studies have revealed that epithelial MHC-II expression is dynamically regulated by cytokines, the gut microbiota, dietary factors, and microbiota-derived metabolites, linking environmental signals to local adaptive immune responses. Dysregulation of epithelial antigen presentation has been implicated in chronic intestinal inflammation, including inflammatory bowel disease (IBD). This review summarizes current knowledge regarding the molecular regulation, spatial organization, and immunological functions of epithelial MHC-II and discusses its emerging role in host–microbiota interactions, mucosal barrier homeostasis, and intestinal disease. Full article

Chicken manure and its potential to contaminate water systems through the dispersal of pathogenic bacteria are major concerns in environmental and public health. In this study, a metagenomic analysis was employed to systematically identify and compare bacterial assemblages in chicken manure (CM) and in a contaminated sample of chicken manure wastewater (CMW). Whole DNA was extracted from CM and CMW, followed by whole-genome shotgun sequencing; data analysis was done using online Galaxy software (ver. 26.0.1.dev1). Metagenomic analysis reveals a complex One Health challenge. Data showed that CM and CMW are different in their microbiota, as indicated by a distinct separation of beta diversity values and limited overlapping of species between sample types. In the current study, we found a greatly significant common functional set of adapted bacterial masses, including major pathogenic bacterial groups as well as opportunistic and environmental bacterial species, indicative of a direct contamination from CM and CMW. Notably, in both CM and CMW, a plethora of opportunistic, enteric, and environmental pathogens like Escherichia coli, Salmonella enterica, and Acinetobacter baumannii were found, coupled with an indication of a direct functional flow between both ecosystems as tangled reservoirs. Chicken manure samples showed differences in taxonomic composition and inferred functional profiles at the time of sampling: CM1 was pathogen-enriched, CM2 exhibited strong nitrogen-supportive metabolism, CM3 was dominated by fiber-degrading decomposers, and CM4 showed high methane-producing potential with environmental risk. Such findings underscore the raising of chickens as a potential source of harmful bacteria for the environment. It is important to note that this study represents a preliminary investigation with certain limitations, including the absence of biological replicates, lack of temporal sampling, and limited capacity to infer dynamic ecological interactions. Yet this metagenomic report is more about describing the taxonomy and functional potential of the bacteria, rather than discussing the actual ecological processes of these microorganisms in the environment. Future studies will be required to explore these aspects. Full article

Escherichia coli, Streptococcus equi subsp. zooepidemicus, Klebsiella oxytoca, and Enterococcus durans are microorganisms capable of causing severe infections, particularly in patients with underlying comorbidities or immune dysfunction. We report a rare clinical case of a 65-year-old man with advanced cardiac and hepatic disease who developed severe diarrheal syndrome followed by septic shock, rapid clinical deterioration, and death. Microbiological examination of autopsy specimens from the intestinal wall and spleen identified Escherichia coli O128 with an enterotoxigenic profile (lt+, st+, eae−), together with Streptococcus equi subsp. zooepidemicus, Klebsiella oxytoca, and Enterococcus durans. Histopathological analysis demonstrated catarrhal enteritis with fibrinous deposits, mucosal edema, vascular congestion, and inflammatory infiltration. Although the microbiological findings were partly derived from autopsy material and postmortem bacterial translocation cannot be completely excluded, the concordance between clinical presentation, laboratory findings, and morphological changes supports the presence of a clinically significant infectious process. To our knowledge, this is the first reported human case of fatal polymicrobial infection involving these four pathogens. The case highlights the potential severity of polymicrobial infections in patients with cirrhosis-associated immune dysfunction and underscores the importance of integrated microbiological and molecular diagnostics for accurate etiological assessment. Full article

The development of antimicrobial resistance (AMR) and the emergence of multiresistant pathogens represent a growing global threat to both human and animal health. Beyond the excessive and improper use of antimicrobials in human medicine, irrational use in veterinary medicine, agriculture, and aquaculture significantly contributes to the selection and spread of resistant microorganisms, which can enter the food chain and reach humans through food consumption or handling. Based on results from a recent meta-analysis, the prevalence of antimicrobial-resistant foodborne pathogens in food samples exceeds 10%. The veterinary sector is of particular concern, as a large proportion of antimicrobials are used in animal production, generating strong selective pressure and favoring the dissemination of AMR along the food chain. In an increasingly interconnected global context, resistant pathogens and resistance determinants can disseminate rapidly across sectors and national borders, making strategies confined to a single sector insufficient; therefore, effectively addressing AMR requires a One Health approach encompassing the human, veterinary, and environmental domains. Key mitigation strategies include strengthening antimicrobial stewardship programs, also in animal production, reducing routine prophylactic use of antimicrobials, and improving surveillance, coordinated across sectors and, where possible, further supported by advanced technologies such as artificial intelligence and machine learning. Further efforts are also needed to improve microbiological diagnostics, particularly through rapid and molecular methods, to support timely, targeted therapies and reduce inappropriate empirical treatments. In parallel, investment in new therapeutic options, including innovative molecules, drug combinations, and alternative approaches, remains crucial to effectively countering the growing burden of antimicrobial resistance. Full article

Type 2 diabetes and insulin resistance are increasingly recognized as conditions influenced not only by genetic and lifestyle factors but also by infectious and microbial exposures. Diarrheagenic pathogens, including enterotoxigenic, enteroaggregative, and enterohemorrhagic Escherichia coli, as well as other enteric microorganisms, disrupt the gut microbiota and compromise intestinal barrier integrity. These alterations promote dysbiosis, increased intestinal permeability, and systemic exposure to lipopolysaccharides and other microbial products, leading to metabolic endotoxemia and chronic low-grade inflammation. In parallel, pathogen-induced modulation of host immune responses contributes to adipose tissue inflammation, mitochondrial dysfunction, and impaired insulin signaling. This review summarizes current evidence linking diarrheagenic pathogens to insulin resistance, with emphasis on the microbiota–immune–metabolism axis. Understanding these interactions highlights novel perspectives on the pathogenesis of insulin resistance and suggests that targeted modulation of the gut microbiota or reduction in pathogen-driven inflammation may represent therapeutic opportunities to improve metabolic outcomes. Full article

Advantageous functions have been attributed to amyloid β, which helps explain its expression despite a propensity to aggregate. Besides supporting cognitive processes, it has antimicrobial activity, e.g., amyloid β can entrap pathogens or disrupt their membranes. Since iron is an essential element for invading organisms, limiting its availability is an antimicrobial strategy. This can be achieved by various means, such as reducing circulating iron, as is the case for anemia of inflammation or anemia of chronic disease, which may occur in Alzheimer’s disease. The protein lactoferrin both sequesters iron and generates proteolytic fragments with antimicrobial properties, and amyloid β may have similar traits. Amyloid β, which is derived from proteolytic cleavage of amyloid precursor protein, directly inhibits microorganisms. In addition, it binds redox-active metals, such as iron and copper. After being generated, amyloid β can enter the interstitial fluid and undergo clearance by a variety of mechanisms (e.g., glymphatic system, transport across the blood–brain barrier, and uptake by microglia or astrocytes). This clearance, together with its small size and iron-binding properties, positions amyloid β to perform a surveillance function to access, capture, and export labile iron. By removing extraneous iron, amyloid β also helps to limit metal-catalyzed reactions that cause tissue damage. In summary, besides preventing the aggregation and neurotoxicity of amyloid β, the clearance of amyloid β from the CNS may serve a surveillance function to remove loosely bound iron to avert injury by redox reactions and enable amyloid β to function as a mammalian siderophore making iron unavailable to invading microorganisms. Full article

Pelvic inflammatory disease (PID), although traditionally viewed as a sexually transmitted infection (STI), can also result from non-sexually transmitted microorganisms that display distinct epidemiologic and clinical characteristics. Unlike STI-related PID, these infections are less influenced by sexual behavior, often show a bimodal age distribution, and are linked to bacterial vaginosis (BV)-associated dysbiosis, iatrogenic uterine procedures, postpartum states, or inadequate access to timely screening and care. Non-STI-related PID is usually polymicrobial, predominantly involving BV-associated vaginal, enteric, or urinary commensals that ascend into the upper genital tract, while respiratory tract organisms, mycobacteria, and biofilm-associated pathogens may also play a role. Pathophysiological mechanisms include disruption of the endocervical barrier, mucus degradation, biofilm formation, hematogenous or iatrogenic seeding, and chronic cytokine-mediated inflammation and fibrosis. Clinical manifestations range from asymptomatic/subclinical disease to acute pelvic pain and tubo-ovarian abscess (TOA) and can progress to systemic infection and sepsis. Diagnosing non-STI PID is challenging due to nonspecific symptoms, negative STI tests, and inconclusive imaging findings, while management relies on broad-spectrum antimicrobials with surgery as needed. Given these complexities, this review aims to synthesize current knowledge on non-STI-related PID, clarify key considerations for its diagnosis, management, and prevention, and outline future perspectives to improve clinical outcomes. Full article

The poultry industry plays a major role in the emergence and spread of foodborne zoonotic diseases, particularly those associated with antibiotic-resistant bacteria. These diseases pose substantial global public health challenges, and the increasing development of antimicrobial resistance further intensifies these concerns. In response, scientific efforts have expanded to develop and implement innovative technologies capable of mitigating the rising prevalence of multidrug-resistant (MDR) microorganisms. Therapeutic bacteriophage supplementation has regained significant attention because it can selectively lyse specific bacteria, is cost-effective to produce, offers environmentally favorable characteristics, and provides several advantages over conventional antibiotics. Experimental studies have demonstrated that phage therapy is both safe and effective for controlling poultry-associated enteric pathogens. Phages can be applied at various stages of the poultry production chain, from rearing to processing and distribution, using multiple delivery strategies. Despite certain limitations, the targeted and well-regulated application of phage cocktails offers considerable potential as an alternative to antibiotics for managing MDR infections. The success of bacteriophage therapy depends on several factors, including the timing of administration, dosage, delivery method, and its integration with other therapeutic approaches. Therefore, developing a comprehensive understanding of bacteriophage utilization in poultry production is both timely and necessary. This review examines the applications, constraints, and future opportunities of phage therapy within the commercial poultry industry, with particular emphasis on the mechanisms through which bacteriophages control bacterial infections. Full article

The ubiquitous environmental pollution with micro- and nano-sized plastic particles (MNPs) is a current and significant problem today. At the same time, lung cancer is responsible for the largest number of cancer-related deaths worldwide. Many research groups have investigated the relationship between lung cancer development and exposure to MNPs in recent years. Studies have demonstrated that these particles could enter the respiratory system in a variety of ways—both directly through inhaled air and through the bloodstream, and through internalization in the intestines and other digestive organs. Data regarding the possibility of their aggregation in the respiratory system, thyroid gland, and brain are also concerning, as the harmful effects of MNPs have been proven to depend on their concentration and exposure time. The primary response of cells to plastic particles is an increase in oxidative stress. This is generated both by the cell itself (especially macrophages) and induced by damage caused by mechanical damage to cellular organelles by MNPs. The consequences of MNP exposure can include metabolic disturbances, DNA damage, and mutations, ultimately inducing neoplastic transformation in healthy cells. This can lead to changes in tissue architecture and increase their susceptibility to other pathogens, such as pathogenic microorganisms or heavy metals. These, in turn, can be internalized along with MNPs, forming a corona surrounding them. Full article

The investigation of the human intestinal microbiota has rapidly become one of the most dynamic and interdisciplinary fields in modern biomedical science, and for good reasons. Since the 1990s, when the microbiota was first described as the “neglected organ”, research has expanded exponentially, uncovering its fundamental roles in maintaining immune homeostasis, regulating host metabolism, which gave rise to the term “second liver”, and influencing neural activity through the dense network of enteric neurons, which justifies its characterization as the “second brain”. Furthermore, the remarkable genetic richness of the microbiota, comprising a gene pool vastly exceeding that of the human genome, has earned it the title of the “second genome”. Tracing the origins of this scientific field reveals that the concept of the gut as a complex microbial ecosystem emerged gradually, shaped by pivotal developments in microbiology and medicine throughout the 19th and early 20th centuries. The rise of the germ theory, the advancement of microscopy, and the discovery of key microbial phenomena, including fermentation, decomposition, bacteriophages, probiotics, and antibiotics, collectively transformed our understanding of microorganisms from pathogens to essential symbionts. This review aims to provide a historical perspective on how these landmark discoveries laid the conceptual and methodological foundations for contemporary microbiota research. By highlighting the scientific milestones that shifted perceptions of microbes from “bad germs” to “good germs”, it seeks to offer readers, whether from biomedical, ecological, or philosophical backgrounds, an integrative view of how this paradigm evolved and why it remains central to current human health discussions. Full article

Despite growing recognition of the role of the gut microbiome in host health and in modulating pathogen activity, the dynamic and reciprocal relationship between enteric viruses and the gut microbial ecosystem remains insufficiently defined and requires further exploration. This comprehensive review examines the bidirectional interplay between the gut microbiome and enteric viral infections by addressing (i) viruses associated with gastrointestinal alterations, (ii) how enteric viral infections alter the composition and function of the gut microbiome, (iii) how the gut microbiome modulates viral infectivity and host susceptibility, and (iv) current microbial-based approaches for preventing or treating enteric viral infections. Gastrointestinal viral infections induce gut microbiome dysbiosis, marked by reductions in beneficial bacteria and increases in potentially pathogenic populations. Specific gut microorganisms can modulate host susceptibility, with certain bacterial genera increasing or decreasing infection risk and disease severity. Pattern recognition receptors in the intestinal epithelium detect microbial signals and trigger antimicrobial peptides, mucus, and interferon responses to control viral replication while maintaining tolerance to commensal bacteria. The gut microbiome can indirectly facilitate viral infections by creating a tolerogenic environment, suppressing antiviral antibody responses, and modulating interferon signaling, or directly enhance viral replication by stabilizing virions, promoting host cell attachment, and facilitating coinfection and viral recombination. In turn, commensal gut bacteria can inhibit viral entry, enhance host antiviral responses, and strengthen mucosal barrier function, contributing to protection against gastrointestinal viral infections. Probiotics and fecal microbiota transplantation constitute potential microbial-based therapeutics that support antiviral defenses, preserve epithelial integrity, and restore microbial balance. In conclusion, the role of the gut microbiome in modulating enteric viral infections represents a promising area of future investigation. Therefore, integrating microbiome insights with virology and immunology could enable predictive and personalized strategies for prevention and treatment. Full article

Aeromonas hydrophila and A. dhakensis are ubiquitous microorganisms, widespread in aquatic environments, and can cause severe infections in humans and animals. This study aimed to determine the diversity of virulence genes aerA, hlyA, act, and alt through polymerase chain reaction and the antimicrobial resistance through disk diffusion test of 101 A. hydrophila and 34 A. dhakensis strains from environmental, animal, and human sources gathered between 2016 and 2019 at the National Reference Laboratory for Enteric Diseases. Overall, the virulence gene distribution was act in 35.5% of the samples, alt in 40.7%, aerA in 42.2%, and hlyA in 44.5%. Our results revealed that 76.3% of the 135 isolated Aeromonas exhibited at least one of the genes above. 76.3% of A. hydrophila and 76.5% of A. dhakensis exhibited virulence genes distributed among 15 and 12 virulence profiles, respectively. Antimicrobial resistance was observed in 86% of the strains (87.1% in A. hydrophila and 82.4% in A. dhakensis), with higher rates of resistance to Nalidixic acid (69.3%), Imipenem (31.1%), and Sulfamethoxazole-trimethoprim (15.5%). The occurrence of virulence genes and antimicrobial resistance in A. hydrophila and A. dhakensis from different sources indicates their diversity and pathogenicity, reinforcing that they can be a potential health risk source. Full article

The oral–gut microbiota axis is a relatively new field of research. Although most studies have focused separately on the oral and gut microbiota, emerging evidence has highlighted that the two microbiota are interconnected and may influence each other through various mechanisms shaping systemic health. The aim of this review is therefore to provide an overview of the interactions between oral and gut microbiota, and the influence of diet and related metabolites on this axis. Pathogenic oral bacteria, such as Porphyromonas gingivalis and Fusobacterium nucleatum, can migrate to the gut through the enteral route, particularly in individuals with weakened gastrointestinal defenses or conditions like gastroesophageal reflux disease, contributing to disorders like inflammatory bowel disease and colorectal cancer. Bile acids, altered by gut microbes, also play a significant role in modulating these microbiota interactions and inflammatory responses. Oral bacteria can also spread via the bloodstream, promoting systemic inflammation and worsening some conditions like cardiovascular disease. Translocation of microorganisms can also take place from the gut to the oral cavity through fecal–oral transmission, especially within poor sanitary conditions. Some metabolites including short-chain fatty acids, trimethylamine N-oxide, indole and its derivatives, bile acids, and lipopolysaccharides produced by both oral and gut microbes seem to play central roles in mediating oral–gut interactions. The complex interplay between oral and gut microbiota underscores their crucial role in maintaining systemic health and highlights the potential consequences of dysbiosis at both the oral and gastrointestinal level. Some dietary patterns and nutritional compounds including probiotics and prebiotics seem to exert beneficial effects both on oral and gut microbiota eubiosis. A better understanding of these microbial interactions could therefore pave the way for the prevention and management of systemic conditions, improving overall health outcomes. Full article