Bacteria from gut microbiota associated with diarrheal infections in children promote virulence of Shiga toxin-producing and enteroaggregative Escherichia coli pathotypes

Enteroaggregative Escherichia coli in mid-Norway: A prospective, case control study

BACKGROUND

The use of molecular methods has led to increased detection of Enteroaggregative Escherichia coli (EAEC) in faecal samples. Studies have yielded conflicting results regarding the clinical relevance of this finding. The objective of this study was to investigate the prevalence of EAEC in faecal samples from patients with diarrhoea and healthy controls and describe characteristics of EAEC positive persons.

METHODS

From March 1st, 2017 to February 28th, 2019, we investigated all consecutive faecal samples from patients with diarrhoea received at the laboratory and collected faecal samples from randomly invited healthy controls from mid-Norway. Real-time multiplex PCR was used for detection of bacterial, viral, and parasitic pathogens. We registered sex, age, urban versus non-urban residency, and travel history for all participants. Statistical analyses were performed with Pearson chi-squared test, Kruskal-Wallis test, and Mann-Whitney U test.

RESULTS

We identified EAEC in 440 of 9487 (4.6%) patients with diarrhoea and 8 of 375 (2.2%) healthy controls. The EAEC prevalence was 19.1% among those with diarrhoea and recent foreign travel and 2.2% in those without travel history independent of diarrhoea. Concomitant pathogens were detected in 64.3% of EAEC-positive patients with diarrhoea. The median age was 28.5 in those with EAEC-positive diarrhoea and 38 in those with EAEC-negative diarrhoea (p <0.01). In patients with diarrhoea, travel was reported in 72% of those with EAEC and concomitant pathogens, and 54% and 12% in those with only EAEC and no EAEC, respectively (p <0.01).

CONCLUSIONS

EAEC was a common detection, particularly in patients with diarrhoea and recent international travel, and was found together with other intestinal pathogens in the majority of cases. Our results suggest that domestically acquired EAEC is not associated with diarrhoea. Patients with EAEC-positive diarrhoea and concomitant pathogens were young and often reported recent travel history compared to other patients with diarrhoea.

Red pandas with different diets and environments exhibit different gut microbial functional composition and capacity

The red panda (Ailurus fulgens) is a distinctive mammal known for its reliance on a diet primarily consisting of bamboo. The gut microbiota and overall health of animals are strongly influenced by diets and environments. Therefore, conducting research to explore the taxonomical and functional variances within the gut microbiota of red pandas exposed to various dietary and environmental conditions could shed light on the dynamic complexities of their microbial communities. In this study, normal fecal samples were obtained from red pandas residing in captive and semi-free environments under different dietary regimes and used for metabolomic, 16S rRNA, and metagenomic sequencing analysis, with the pandas classified into four distinct cohorts according to diet and environment. In addition, metagenomic sequencing was conducted on mucus fecal samples to elucidate potential etiological agents of disease. Results revealed an increased risk of gastrointestinal diseases in red pandas consuming bamboo shoots due to the heightened presence of pathogenic bacteria, although an increased presence of microbiota-derived tryptophan metabolites appeared to facilitate intestinal balance. The red pandas fed bamboo leaves also exhibited a decrease in gut microbial diversity, which may be attributed to the antibacterial flavonoids and lower protein levels in leaves. Notably, red pandas residing in semi-free environments demonstrated an enriched gut microbial diversity. Moreover, the occurrence of mucus secretion may be due to an increased presence of species associated with diarrhea and a reduced level of microbiota-derived tryptophan metabolites. In summary, our findings substantiate the influential role of diet and environment in modulating the gut microbiota of red pandas, offering potential implications for improved captive breeding practices.

Dynamic Interactions between Diarrhoeagenic Enteroaggregative Escherichia coli and Presumptive Probiotic Bacteria: Implications for Gastrointestinal Health

This study delves into the temporal dynamics of bacterial interactions in the gastrointestinal tract, focusing on how probiotic strains and pathogenic bacteria influence each other and human health. This research explores adhesion, competitive exclusion, displacement, and inhibition of selected diarrhoeagenic Escherichia coli (D-EAEC) and potential probiotic strains under various conditions. Key findings reveal that adhesion is time-dependent, with both D-EAEC K2 and probiotic L. plantarum FS2 showing increased adhesion over time. Surprisingly, L. plantarum FS2 outperformed D-EAEC K2 in adhesion and exhibited competitive exclusion and displacement, with inhibition of adhesion surpassing competitive exclusion. This highlights probiotics' potential to slow pathogen attachment when not in competition. Pre-infecting with L. plantarum FS2 before pathogenic infection effectively inhibited adhesion, indicating probiotics' ability to prevent pathogen attachment. Additionally, adhesion correlated strongly with interleukin-8 (IL-8) secretion, linking it to the host's inflammatory response. Conversely, IL-8 secretion negatively correlated with trans-epithelial electrical resistance (TEER), suggesting a connection between tight junction disruption and increased inflammation. These insights offer valuable knowledge about the temporal dynamics of gut bacteria interactions and highlight probiotics' potential in competitive exclusion and inhibiting pathogenic bacteria, contributing to strategies for maintaining gastrointestinal health and preventing infections.

Crosstalk between Gut Microbiota and Host Immunity: Impact on Inflammation and Immunotherapy

Gut microbes and their metabolites are actively involved in the development and regulation of host immunity, which can influence disease susceptibility. Herein, we review the most recent research advancements in the gut microbiota-immune axis. We discuss in detail how the gut microbiota is a tipping point for neonatal immune development as indicated by newly uncovered phenomenon, such as maternal imprinting, in utero intestinal metabolome, and weaning reaction. We describe how the gut microbiota shapes both innate and adaptive immunity with emphasis on the metabolites short-chain fatty acids and secondary bile acids. We also comprehensively delineate how disruption in the microbiota-immune axis results in immune-mediated diseases, such as gastrointestinal infections, inflammatory bowel diseases, cardiometabolic disorders (e.g., cardiovascular diseases, diabetes, and hypertension), autoimmunity (e.g., rheumatoid arthritis), hypersensitivity (e.g., asthma and allergies), psychological disorders (e.g., anxiety), and cancer (e.g., colorectal and hepatic). We further encompass the role of fecal microbiota transplantation, probiotics, prebiotics, and dietary polyphenols in reshaping the gut microbiota and their therapeutic potential. Continuing, we examine how the gut microbiota modulates immune therapies, including immune checkpoint inhibitors, JAK inhibitors, and anti-TNF therapies. We lastly mention the current challenges in metagenomics, germ-free models, and microbiota recapitulation to a achieve fundamental understanding for how gut microbiota regulates immunity. Altogether, this review proposes improving immunotherapy efficacy from the perspective of microbiome-targeted interventions.