Mars, Ruben A.

Background: Variability in recanalization success during endovascular treatment for acute ischemic stroke (AIS) has led to increased interests in thrombus composition and associated cellular materials. While evidence suggests that bacteria may influence thrombus characteristics, limited data exist on microbiological profiles of thrombi in stroke patients. Objectives: Characterization of bacterial communities present in thrombi of AIS patients undergoing mechanical thrombectomy, providing insights into microbial contributions to stroke pathogenesis and treatment outcomes. Methods: Thrombi were collected from 20 AIS patients. After extracting metagenome, 16S rDNA sequencing was performed. Bioinformatic analysis included taxonomy and diversity assessments. The presence of bacterial DNA and viable bacteria in thrombi was validated using polymerase chain reaction (PCR) and bacterial culturing followed by matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) analysis, respectively. Results: 16S rDNA was amplified in 19/20 thrombi (95%). Analysis identified a diverse microbial community, with Corynebacterium spp. as the most prevalent genus, followed by Staphylococcus spp., Bifidobacterium spp., Methylobacterium spp., and Anaerococcus spp. Alpha diversity analyses (Shannon index: 4.0–6.0 and Simpson index: 0.8–1.0) revealed moderate to high microbial diversity across samples; beta diversity demonstrated distinct clustering, indicating inter-patient variability in microbial profiles. PCR confirmed the presence of DNA specific to dominant bacterial taxa identified through sequencing. Culturing showed the presence of Staphylococcus epidermidis and Enterococcus faecalis in some clots as identified through MALDI analysis. Conclusions: This study shows bacterial communities present in AIS patients’ thrombi, suggesting a potential link between microbial signatures and thrombus characteristics.

Disorders of Gut‐Brain Interaction (DGBI) are widely prevalent and commonly encountered in gastroenterology practice. While several peripheral and central mechanisms have been implicated in the pathogenesis of DGBI, a recent body of work suggests an important role for the gut microbiome. In this review, we highlight how gut microbiota and their metabolites affect physiologic changes underlying symptoms in DGBI, with a particular focus on their mechanistic influence on GI transit, visceral sensitivity, intestinal barrier function and secretion, and CNS processing. This review emphasizes the complexity of local and distant effects of microbial metabolites on physiological function, influenced by factors such as metabolite concentration, duration of metabolite exposure, receptor location, host genetics, and underlying disease state. Large‐scale in vitro work has elucidated interactions between host receptors and the microbial metabolome but there is a need for future research to integrate such preclinical findings with clinical studies. The development of novel, targeted therapeutic strategies for DGBI hinges on a deeper understanding of these metabolite‐host interactions, offering exciting possibilities for the future of treatment of DGBI.

Abstract Background As the acute phase of the COVID-19 pandemic subsides, an increasing number of individuals are recognized as having long COVID, affecting over 65 million people worldwide. Recent studies have suggested a potential link between long COVID and alterations in the gut microbiome. In this study, we examined the gut microbiome of a large outpatient cohort during acute phase of infection, with the ultimate goal of determining predictors of long-term COVID-19 health outcomes. Methods We conducted a study of 394 COVID-19 patients with positive SARS-CoV-2 testing from November 2020 to September 2021 at a multi-site healthcare system. Long COVID was defined as the persistence of symptoms for four weeks or more after illness onset. DNA extraction was performed using the MoBio PowerSoil Pro DNA isolation kit. Samples were sequenced using shotgun metagenomics. Stool SARS-CoV-2 RNA was tested using qRT-PCR of the E gene, and stool ELISA was performed for calprotectin levels. Standard biostatistical tools in R (v 4.2.3) were used for statistical analysis. Results Of the 394 COVID-19 patients, 84 (21%) had long COVID, with fatigue being the most common persistent symptom (Table 1). No significant differences were seen in age, BMI, and antibiotic use. Those with long COVID were more likely to be female, had higher Charlson's comorbidity scores, more severe index illnesses. However, the two groups had no difference in SARS-CoV-2 stool PCR positivity or stool calprotectin levels (Table 2). Principal coordinate analysis of Bray Curtis dissimilarities revealed that patients with long COVID had a distinct microbial composition compared with those without long COVID during the acute phase of infection (ANOSIM R2= 0.005, P= 0.01). Categorizing patients by number of long COVID symptoms showed significant differences among groups (ANOSIM R2=0.1, P=0.007), mainly between patients with >3 symptoms and those with 0-1 symptoms (Bonferroni, P= 0.018). Alpha diversity was lower in patients with > 3 symptoms, although this was not statistically significant (Shannon diversity, two-way-ANOVA, P=0.051). Figure 1 Conclusion Long COVID patients show distinct gut microbial composition during the acute phase of infection, suggesting a potential role in predicting long-term COVID health outcomes. Disclosures John C. O'Horo, Sr., MD, MPH, Janssen Pharmaceuticals.: Grant/Research Support|nference: Grant/Research Support Purna C. Kashyap, MD, Intrinsic Medicine: Advisor/Consultant|Novome Biotechnologies: Advisor/Consultant|Pendulum Therapeutics: Advisor/Consultant