Gut Pathogens最新文献

The fungi of the human microbiota play important roles in the nutritional metabolism and immunological balance of the host. Recently, research has increasingly emphasised the role of fungi in modulating inflammation in intestinal diseases and maintaining health in this environment. It is therefore necessary to understand more clearly the interactions and mechanisms of the microbiota/pathogen/host relationship and the resulting inflammatory processes, as well as to offer new insights into the prevention, diagnosis and treatment of inflammatory bowel disease (IBD), colorectal cancer (CRC) and other intestinal pathologies. In this review, we comprehensively elucidate the fungal-associated pathogenic mechanisms of intestinal inflammation in IBD and related CRC, with an emphasis on three main aspects: the direct effects of fungi and their metabolites on the host, the indirect effects mediated by interactions with other intestinal microorganisms and the immune regulation of the host. Understanding these mechanisms will enable the development of innovative approaches based on the use of fungi from the resident human microbiota such as dietary interventions, fungal probiotics and faecal microbiota transplantation in the prevention, diagnosis and treatment of intestinal diseases.

Background: Celiac disease is an autoimmune disorder triggered by dietary gluten in genetically predisposed individuals that primarily affects the small intestine. Studies have reported differentially abundant bacterial taxa in the gut microbiota of celiac patients compared with non-celiac controls. However, findings across studies have inconsistencies and no microbial signature of celiac disease has been defined so far.

Results: Here, we showed, by comparing celiac patients with their non-celiac 1st-degree relatives, that bacterial communities of related individuals have similar species occurrence and abundance compared with non-relatives, regardless the disease status. We also found in celiac patients a loss of bacterial species associated with fiber degradation, and host metabolic and immune modulation, as ruminiclostridia, ruminococci, Prevotella, and Akkermansia muciniphila species. We demonstrated that the differential abundance of bacterial species correlates to different dietary patterns observed between the two groups. For instance, Ruminiclostridium siraeum, Ruminococcus bicirculans, and Bacteroides plebeious, recognized as fiber-degraders, appear more abundant in non-celiac 1st-degree relatives, which have a vegetable consumption pattern higher than celiac patients. Pattern of servings per day also suggests a possible link between these species' abundance and daily calorie intake.

Conclusions: Overall, we evidenced that a kinship approach could be valuable in unveiling potential celiac disease microbial traits, as well as the significance of dietary factors in shaping microbial profiles and their influence on disease development and progression. Our results pave the way for designing and adopting novel dietary strategies based on gluten-free fiber-enriched ingredients to improve disease management and patients' quality of life.

Classification of pathogenic E. coli has been focused either in mammalian host or infection site, which offers limited resolution. This review presents a comprehensive framework for classifying all E. coli branches within a single, unifying figure. This approach integrates established methods based on virulence factors, serotypes and clinical syndromes, offering a more nuanced and informative perspective on E. coli pathogenicity. The presence of the LEE island in pathogenic E. coli is a key genetic marker differentiating EHEC from STEC strains. The coexistence of stx and eae genes within the bacterial genome is a primary characteristic used to distinguish STEC from other pathogenic E. coli strains. The presence of the inv plasmid, Afa/Dr adhesins, CFA-CS-LT-ST and EAST1 are key distinguishing features for identifying pathogenic E. coli strains belonging to EIEC, DAEC, ETEC and EAEC pathotypes respectively. Food microbiological criteria differentiate pathogenic E. coli in food matrices. 'Zero-tolerance' applies to most ready-to-eat (RTE) foods due to high illness risk. Non-RTE foods' roles may allow limited E. coli presence, which expose consumers to potential risk; particularly from the concerning Shiga toxin-producing E. coli (STEC) strains, which can lead to life-threatening complications in humans, including haemolytic uremic syndrome (HUS) and even death in susceptible individuals. These findings suggest that decision-makers should consider incorporating the separate detection of STEC serotypes into food microbiological criteria, in addition to existing enumeration methods. Contamination of STEC is mainly linked to food consumption, therefore, outbreaks of E. coli STEC has been reviewed here and showed a link also to water as a potential contamination route. Since their discovery in 1982, over 39,787 STEC cases associated with 1,343 outbreaks have been documented. The majority of these outbreaks occurred in the Americas, followed by Europe, Asia and Africa. The most common serotypes identified among the outbreaks were O157, the 'Big Six' (O26, O45, O103, O111, O121, and O145), and other serotypes such as O55, O80, O101, O104, O116, O165, O174 and O183. This review provides valuable insights into the most prevalent serotypes implicated in STEC outbreaks and identifies gaps in microbiological criteria, particularly for E. coli non-O157 and non-Big Six serotypes.

Background: Age-related gut microbial changes have been widely investigated over the past decade. Most of the previous age-related microbiome studies were conducted on the Western population, and the short-read sequencing (e.g., 16S V4 or V3-V4 region) was the most common microbiota profiling method. We evaluated the gut compositional differences using the long-read sequencing approach (i.e., PacBio sequencing targeting the full-length V1-V9 regions) to enable a deeper taxonomic resolution and better characterize the gut microbiome of Singaporeans from different age groups.

Results: A total of 83 research participants were included in this study. Although no significant differences were detected in alpha and beta diversity, our study demonstrated several bacterial taxa with abundances that were significantly different across age groups. With young individuals as the reference group, Eggerthella lenta and Bacteroides uniformis were found to be significantly altered in the middle-aged group, while Catenibacterium mitsuokai and Bacteroides plebeius were significantly altered in the elderly group. These age-related differences in the gut microbiome were associated with aberrations in several predicted functional pathways, including dysregulations of pathways related to lipopolysaccharide and tricarboxylic acid cycle in older adults.

Conclusions: The utilization of long-read sequencing facilitated the identification of species- and strain-level differences across age groups, which was challenging with the partial 16S rRNA sequencing approach. Nevertheless, replication studies are warranted to confirm our findings, and if confirmed, further in vitro and in vivo studies are crucial to better understand the impact of the altered levels of age-related bacterial taxa. Additionally, the modest performance of strain-level taxonomic classification using 16S-ITS-23S gene sequences, likely due to the limited depth of currently available alignment databases, highlights the need for optimization and refinement in curating these databases for the long-read sequencing approach.

Background: Human cryptosporidiosis is distributed worldwide, and it is recognised as a leading cause of acute diarrhoea and death in infants in low- and middle-income countries. Besides immune status, the higher incidence and severity of this gastrointestinal disease in young children could also be attributed to the digestive environment. For instance, human gastrointestinal physiology undergoes significant changes with age, however the role this variability plays in Cryptosporidium parvum pathogenesis is not known. In this study, we analysed for the first time the impact of digestive physicochemical parameters on C. parvum infection in a human and age-dependent context using a dynamic in vitro gastrointestinal model.

Results: Our results showed that the parasite excystation, releasing sporozoites from oocysts, occurs in the duodenum compartment after one hour of digestion in both child (from 6 months to 2 years) and adult experimental conditions. In the child small intestine, slightly less sporozoites were released from excystation compared to adult, however they exhibited a higher luciferase activity, suggesting a better physiological state. Sporozoites collected from the child jejunum compartment also showed a higher ability to invade human intestinal epithelial cells compared to the adult condition. Global analysis of the parasite transcriptome through RNA-sequencing demonstrated a more pronounced modulation in ileal effluents compared to gastric ones, albeit showing less susceptibility to age-related digestive condition. Further analysis of gene expression and enriched pathways showed that oocysts are highly active in protein synthesis in the stomach compartment, whereas sporozoites released in the ileum showed downregulation of glycolysis as well as strong modulation of genes potentially related to gliding motility and secreted effectors.

Conclusions: Digestion in a sophisticated in vitro gastrointestinal model revealed that invasive sporozoite stages are released in the small intestine, and are highly abundant and active in the ileum compartment, supporting reported C. parvum tissue tropism. Our comparative analysis suggests that physicochemical parameters encountered in the child digestive environment can influence the amount, physiological state and possibly invasiveness of sporozoites released in the small intestine, thus potentially contributing to the higher susceptibility of young individuals to cryptosporidiosis.

Toxoplasmosis, caused by Toxoplasma gondii, has the unsettling ability to infect nearly every warm-blooded vertebrate. When transmitted from mother to fetus during pregnancy, it can lead to congenital toxoplasmosis in newborns, which may have severe and even fatal outcomes. Moreover, this parasite is a significant cause of reproductive issues in cattle. The aim of this literature review was to compile and synthesize information on the epidemiology and clinical features of naturally occurring Toxoplasma gondii infections in both humans and animals, as well as to assess the occurrence of oocysts in the environmental matrices in Morocco. To achieve these objectives, data were sourced from four electronic databases: PubMed, Web of Science, Scopus, and Google Scholar. A total of 32 articles published between January 1, 2000, and January 31, 2024, met the inclusion criteria. The findings indicated that the seroprevalence of T. gondii among pregnant women varied by city and appeared to be lower in drier climates. The study identified several risk factors associated with T. gondii infection among women in Morocco, including direct contact with soil, failure to wash fruits and vegetables before eating, limited education, and reliance on well water for drinking. Moreover, there is a limited amount of serological data on T. gondii in animals. In Morocco, the prevalence of this parasite can reach up to 30% in sheep, while it stands at 8.5% in cattle and goats. Leafy greens are particularly prone to hosting pathogens and are associated with foodborne outbreaks. In Morocco, the prevalence of T. gondii in leafy vegetables is around 16%, although soil analyses have not found any oocysts. This review offers a thorough epidemiological overview of T. gondii infections in Morocco, serving as a valuable resource for researchers and aiding in the development of control and prevention programs.

Background: Diverse bacterial group behaviors are controlled by quorum sensing, a regulatory network of bacterial gene expression based on cell density, and involving communication through chemical signal molecules called autoinducers. Multidisciplinary research in toxigenic Vibrio cholerae the etiologic agent of cholera, appear to suggest group behavior in the ecology, epidemiology, pathogenesis and transmission of the pathogen. This review summarizes latest advances and known aspects of quorum regulated environmental survival form of V. cholerae, and their role in cholera outbreaks, as well as the significance of this knowledge in tracking the pathogen for prevention of cholera.

Main body: Pathogenic V. cholerae naturally exists in aquatic reservoirs, and infects humans, often leading to epidemic outbreaks of cholera. Effective detection and monitoring of the pathogen in surface waters have been a research focus in preventing cholera outbreaks. However, in the aquatic reservoirs, V. cholerae persists mostly in a quiescent state referred to as viable but non-culturable (VBNC), or conditionally viable environmental cells (CVEC), which fail to grow in routine bacteriological culture. The presence of CVEC can, however, be observed by fluorescent antibody based microscopy, and they appear as clumps of cells embedded in an exopolysaccharide matrix. Current studies suggest that CVEC found in water are derived from in-vivo formed biofilms excreted by cholera patients. The transition to CVEC occurs when dilution of autoinducers in water blocks quorum-mediated regulatory responses that would normally disperse the cellular aggregates. Consequently, CVEC are resuscitated to actively growing cells if autoinducers are replenished, either in the laboratory, or naturally by other environmental bacteria or the intestinal microbiota when CVEC are ingested by humans or aquatic animals.

Conclusion: Quorum sensing plays a crucial role in the environmental persistence of toxigenic V. cholerae in a latent state, and their periodic emergence to cause cholera outbreaks. Furthermore, the autoinducer driven resuscitation of these cells may be a basis for improving the detection of V. cholerae in water samples, and monitoring V. cholerae in their aquatic reservoirs in cholera endemic areas.

Background: Bioinspired nanomaterials have widely been employed as suitable alternatives for controlling biofilm and pathogens due to their distinctive physico-chemical properties.

Methodology: This study explored the antibiofilm as well as photocatalytic potential of silver (Ag) nanoparticles (NPs) synthesized using the cell-free supernatant of Lactobacillus acidophilus for the disinfection of multi-drug-resistant (MDR) strains of enteroaggregative E. coli (EAEC), Salmonella Typhimurium, S. Enteritidis and methicillin-resistant Staphylococcus aureus (MRSA) on exposure to LED light. In addition, the removal of toxic cationic dyes i.e., methylene blue (MB), rhodamine B (RhB) and crystal violet (CV) was explored on exposure to sunlight, LED and UV lights.

Results: Initially, the synthesis of AgNPs was verified using UV- Vis spectroscopy, X-ray diffraction and transmission electron microscopy. The synthesized AgNPs exhibited MIC and MBC values of 7.80 and 15.625 µg/mL, respectively. The AgNPs exhibited significant inhibition (P < 0.001) in the biofilm-forming ability of all the tested MDR isolates. On exposure to LED light, the AgNPs could effectively eliminate all the tested MDR isolates in a dose-dependent manner. While performing photocatalytic assays, the degradation of RhB was observed to be quite slower than MB and CV irrespective of the tested light sources. Moreover, the sunlight as well as UV light exhibited better photodegradation capacity than LED light. Notwithstanding the light sources, RhB followed zero-order kinetics; however, MB and CV followed primarily second-order kinetics.

Conclusion: The green synthesized AgNPs were found to be an effective photocatalytic as well as antifouling candidate that could be applied in therapeutics and wastewater treatment.

Background: Fusobacterium nucleatum (F. nucleatum) is one of the key tumorigenic bacteria in colorectal cancer (CRC), yet how F. nucleatum is involved in colorectal cancer carcinogenesis remains unknown.

Results: In the present study, we carried out PathSeq analysis on RNA sequencing data from the 430 primary colon adenocarcinomas in TCGA database to assess the relationship between patients' survival and F. nucleatum abundance. Among patients with cecum and ascending colon tumors, we found that F. nucleatum transcriptome abundance is positively correlated with mutation load. We further demonstrated that patients with both high tumoral abundance of F. nucleatum and high mutation load exhibited poorer survival and DNA damage. We furthermore determined that F. nucleatum-conditioned medium (Fn. CM) induces DNA damage in both in vitro and in vivo studies. In addition, two F. nucleatum-secreted mutagens, namely DL-homocystine and allantoic acid, were identified to lead to DNA damage.

Conclusions: Our finding delineates the genotoxicity of F.nucleatum-secreted mutagens, which provides a basis for further work to investigate the role of F. nucleatum in the pathogenicity of CRC.