Fecal Abundance Research Articles

Faecal Volatile Organic Compounds to Detect Colorectal Neoplasia in Lynch Syndrome-A Prospective Longitudinal Multicentre Study.

Non-invasive biomarkers may reduce post-colonoscopy colorectal cancer (CRC) rates and colonoscopy overuse in Lynch syndrome. Unlike faecal immunochemical test (FIT), faecal volatile organic compounds (VOCs) may accurately detect both advanced and non-advanced colorectal neoplasia. The aim of this study was to evaluate the potential of faecal VOCs-separately and with FIT-to guide optimal colonoscopy intervals in Lynch syndrome. Prospective longitudinal multicentre study in which individuals with Lynch syndrome collected faeces before and after high-quality surveillance colonoscopy. VOC-patterns were analysed using field asymmetric ion mobility spectrometry (FAIMS) and gas chromatography-ion mobility spectrometry (GC-IMS) followed by machine learning pipelines, and combined with FIT at 2.55 μg Hb/g faeces. Gas chromatography time-of-flight mass spectrometry analysed individual VOC abundance. Among 200 included individuals (57% female, median 51 years), 62 had relevant neoplasia at colonoscopy: 3 CRC, 6 advanced adenoma (AA), 3 advanced serrated lesion (ASL), and 50 non-advanced adenoma (NAA). Respective sensitivity and negative predictive value for CRC and AA (and also ASL in case of FAIMS) were 100% and 100% using FAIMS (54% specificity), and 89% and 99% using GC-IMS (58% specificity). Respective sensitivity and specificity for any relevant neoplasia were 88% and 44% (FAIMS) and 84% and 28% (GC-IMS); accuracy did not significantly improve upon VOC-FIT. VOC-patterns differed before and after polypectomy (AUC 0.70). NAA showed decreased faecal abundance of butanal, 2-oxohexane, dimethyldisulphide and dimethyltrisulphide. In Lynch syndrome, faecal VOCs may be a promising strategy for postponing colonoscopy and for follow-up after polypectomy. Our results serve as a stepping stone for large validation studies. NL8749.

Relationships between fecal indicator abundance in water and sand and the presence of pathogenic genes in sand of recreational beaches.

For decades, the risk of exposure to infectious diseases in recreational beaches has been evaluated through the quantification of fecal indicator bacteria in water samples using culture methods. The analyses of sand samples have recently been developed as a complement to the monitoring of recreational waters in beach quality assessments. The growing use of molecular techniques for environmental monitoring allows for the rapid detection of pathogenic genes, thus providing more accurate information regarding the health risk of exposure to contaminated sand. The aim of this work was to determine the relationship between the fecal indicators abundance in water and sand and the presence of Shiga toxin-producer Escherichia coli (STEC) in sand by analyzing samples from touristic beaches using culture-dependent (fecal coliforms assay) and culture-independent (real-time PCR of stx1, stx2, and eae genes) techniques. We found a high concentration of coliform bacteria in water and sand in several beaches in eastern Uruguay, with different levels of sanitation networks and levels of urbanization. The presence of STEC virulence genes (mainly stx1) was confirmed in 8 out of 20 sand samples. The recreational use of sandy beaches may imply a risk to the health of its users, especially near streams and creek outflows, thus highlighting the need of monitoring sand bacteriological quality and pathogens using molecular tools.

Baseline gut microbiome as a predictive biomarker of response to probiotic adjuvant treatment in gout management

Gout is characterized by dysregulation of uric acid (UA) metabolism, and the gut microbiota may serve as a regulatory target. This two-month randomized, double-blind, placebo-controlled trial aimed to investigate the additional benefits of coadministering Probio-X alongside febuxostat. A total of 160 patients with gout were randomly assigned to either the probiotic group (n = 120; Probio-X [1 ×1011 CFU/day] with febuxostat) or the placebo group (n = 40; placebo material with febuxostat). Coadministration of Probio-X significantly decreased serum UA levels and the rate of acute gout attacks (P < 0.05). Based on achieving a target sUA level (360 μmol/L) after the intervention, the probiotic group was further subdivided into probiotic-responsive (ProA; n = 54) and probiotic-unresponsive (ProB; n = 66) subgroups. Post-intervention clinical indicators, metagenomic, and metabolomic changes in the ProB and placebo groups were similar, but differed from those in the ProA group, which exhibited significantly lower levels of acute gout attack, gout impact score, serum indicators (UA, XOD, hypoxanthine, and IL-1β), and fecal gene abundances of UA-producing pathways (KEGG orthologs of K13479 and K01487; gut metabolic modules for formate conversion and lactose and galactose degradation). Additionally, the ProA group showed significantly higher levels (P < 0.05) of gut SCFAs-producing bacteria and UA-related metabolites (xanthine, hypoxanthine, bile acids) after the intervention. Finally, we established a gout metagenomic classifier to predict probiotic responsiveness based on subjects’ baseline gut microbiota composition. Our results indicate that probiotic-driven therapeutic responses are highly individual, with the probiotic-responsive cohort benefitting significantly from probiotic coadministration.

Fecal Proteolytic Bacteria and Staphylococcal Superantigens Are Associated With Abdominal Pain Severity in Irritable Bowel Syndrome.

Changes in the composition of the gut microbiota have been associated with the development of irritable bowel syndrome (IBS). However, to what extent specific bacterial species relate to clinical symptoms remains poorly characterized. We investigated the clinical relevance of bacterial species linked with increased proteolytic activity, histamine production, and superantigen (SAg) production in patients with IBS. Fecal (n = 309) and nasal (n = 214) samples were collected from patients with IBS and healthy volunteers (HV). Clinical symptoms and gut transit time were evaluated. Bacterial abundance in feces and nasal swabs as well as fecal trypsin-like activity were assessed. The percentage of fecal samples containing Staphylococcus aureus was significantly higher in IBS compared with HV. Forty-nine percent of S. aureus -positive fecal samples from patients with IBS were also positive for SAgs, compared with 12% of HV. Patients with IBS and positive fecal SAg-producing S. aureus reported higher pain scores than those without S. aureus . Moreover, increased fecal proteolytic activity was associated with abdominal pain. Fecal abundance of Paraprevotella clara and Alistipes putredinis was significantly decreased in IBS, particularly in samples with higher proteolytic activity. Patients with lower Alistipes putredinis or Faecalibacterium prausnitzii abundance reported more severe abdominal pain. In keeping with our preclinical findings, we show that increased presence of SAg-producing S. aureus in fecal samples of patients with IBS is associated with increased levels of abdominal pain. We also show that increased fecal proteolytic activity is associated with increased abdominal pain in patients with IBS.

PSIX-10 Effects of Bacillus subtilis ATCC PTA-122264 on macronutrient digestibility and fecal characteristics, metabolites, and microbiota of healthy adult dogs subjected to an abrupt diet change

Abstract Probiotic use in dogs is increasing, with spore-forming Bacillus species gaining interest due to their viability during processing, storage, and in the gastrointestinal tract. B. subtilis is known for its adaptable metabolism that may be useful in pets subjected to abrupt dietary changes. The objective of this study was to determine dietary apparent total tract macronutrient digestibility (ATTD) and fecal characteristics, metabolites, and microbiota of healthy adult dogs supplemented with B. subtilis ATCC PTA-122264. All procedures were approved by the University of Illinois IACUC prior to experimentation. Dogs [n = 12; 6 ± 1 yr; 8.71 ± 0.91 kg body weight (BW)] were used in a replicated 3x3 Latin square design (n = 12/group) and fed to maintain BW. In each 42-d experimental period, dogs were allotted to one of three treatments: Control (kibble diet only), Low [kibble diet + 1×109 colony-forming units (CFU) of B. subtilis], and High (kibble diet + 5×109 CFU of B. subtilis). After a 22-d adaptation phase, a 5-d fecal collection phase was followed by a blood collection phase. On d 28, dogs were abruptly changed to a canned diet and fed for 14 d, with fecal samples collected on d 30 (2 d post change), 34 (6 d post change), 38 (10 d post change), and 42 (14 d post change). Fecal microbiota data were evaluated using QIIME2. All other data were analyzed using the Mixed Models procedure of SAS, with P &amp;lt; 0.05 being considered significant. B. subtilis supplementation of the kibble diet did not influence food or energy intake, fecal output, ATTD, most serum metabolites, hematology, fecal characteristics, fecal bacterial alpha and beta diversity indices, and dysbiosis index, demonstrating the safety of the strain in dogs. However, fecal Streptococcus and Blautia abundances were higher in High dogs than Low or Control dogs, while E. coli abundance was less in Low dogs than High and Control dogs. The abrupt change to a canned diet led to significant alterations in fecal characteristics, dysbiosis index, and bacterial abundances, which were not influenced by B. subtilis supplementation. Bacterial alpha diversity measures were affected, with observed ASV (amplicon sequence variants) and the Fisher Index reducing, and the Shannon Index increasing by dietary change. The abrupt dietary change caused a distinct shift in microbial communities, as evidenced by principal coordinates analysis plots. The relative abundances of various fecal bacterial taxa, including Bifidobacterium, Faecalibaculum, Turicibacter, and Lactobacillus were decreased, while Collinsella, Ruminococcus gnavus group, and Escherichia-Shigella were increased with the dietary change. Our data support the notion that daily supplementation of 1 – 5×109 CFU of B. subtilis ATCC PTA-122264 in healthy dogs is safe and does not affect markers of general health and fecal characteristics, warranting further exploration.

Assessing Fecal Microbial Diversity and Hormone Levels as Indicators of Gastrointestinal Health in Reintroduced Przewalski's Horses (Equus ferus przewalskii).

Diarrhea serves as a vital health indicator for assessing wildlife populations post-reintroduction. Upon release into the wild, wild animals undergo adaptation to diverse habitats and dietary patterns. While such changes prompt adaptive responses in the fecal microbiota, they also render these animals susceptible to gastrointestinal diseases, particularly diarrhea. This study investigates variations in fecal microorganisms and hormone levels between diarrhea-afflicted and healthy Przewalski's horses. The results demonstrate a significant reduction in the alpha diversity of the fecal bacterial community among diarrheal Przewalski's horses, accompanied by notable alterations in taxonomic composition. Firmicutes, Proteobacteria, and Bacteroidetes emerge as dominant phyla across all fecal samples, irrespective of health status. However, discernible differences in fecal bacterial abundance are observed between healthy and diarrhea-stricken individuals at the genus level, specifically, a diminished relative abundance of Pseudobutyrivibrio is observed. The majority of the bacteria that facilitate the synthesis of short-chain fatty acids, Christensenellaceae_R_7_group (Christensenellaceae), NK4A214_group (Ruminococcus), Lachnospiraceae_XPB1014_group (Lachnospiraceae), [Eubacterium]_coprostanoligenes_group (Eubacterium), Rikenellaceae_RC9_gut_group, Lachnospiraceae_AC2044_group (Lachnospiraceae), and Prevotellaceae_UcG_001 (Prevotella) are noted in diarrhea-affected Przewalski's horses, while Erysipelotrichaceae, Phoenicibacter, Candidatus_Saccharimonas (Salmonella), and Mogibacterium are present in significantly increased amounts. Moreover, levels of immunoglobulin IgA and cortisol are significantly elevated in the diarrhea group compared with the non-diarrhea group. Overall, this study underscores substantial shifts in fecal bacterial diversity, abundance, and hormone levels in Przewalski's horses during episodes of diarrhea.

Associations of Neonatal Dairy Calf Faecal Microbiota with Inflammatory Markers and Future Performance.

After birth, the immune system is challenged by numerous elements of the extrauterine environment, reflected in fluctuations of inflammatory markers. The concentrations of these markers in the first month of life are associated with the future performance of dairy youngstock. It is thought that bacterial genera colonizing the calf intestinal tract can cause inflammation and thus affect their host's performance via immunomodulation. This study explored how the faecal microbiota of newborn dairy calves were related to inflammatory markers during the first three weeks of life, and if the abundance of specific genera was associated with first-lactation performance. Ninety-five female Holstein calves were studied. Once a week, serum and faecal samples were collected, serum concentrations of serum amyloid A, haptoglobin, tumour necrosis factor-α, and interleukin-6 were measured, and faecal microbiota composition was examined by 16S rRNA gene amplicon sequencing. Faecal Gallibacterium abundance in the first week of age and Collinsella abundance in the second week were negatively associated with inflammatory response as well as with calving-conception interval. Peptostreptococcus abundance in the second week of life was positively associated with inflammatory response and calving-conception interval, and negatively with average daily weight gain. In the third week, Dorea abundance was positively, Bilophila abundance was negatively associated with inflammatory response, and both genera were negatively associated with age at first calving. These bacterial genera may be able to influence the inflammatory response and through this, possibly the future performance of the dairy heifer. Deciphering such microbiota-host interactions can help improve calf management to benefit production and welfare.

Effects of Defatted Rice Bran-Fortified Bread on the Gut Microbiota Composition of Healthy Adults With Low Dietary Fiber Intake: Protocol for a Crossover Randomized Controlled Trial.

Inadequate dietary fiber (DF) intake is associated with several human diseases. Bread is commonly consumed, and its DF content can be increased by incorporating defatted rice bran (DRB). This first human study on DRB-fortified bread primarily aims to assess the effect of DRB-fortified bread on the relative abundance of a composite of key microbial genera and species in fecal samples. Secondary outcomes include clinical (cardiovascular risk profile), patient-reported (daily bread consumption and bowel movement, gut comfort, general well-being, and total DF intake), biological (fecal microbiota gene abundances, and fecal and plasma metabolites), and physiome (whole-gut and regional transit time and gas fermentation profiles) outcomes in healthy adults with low DF intake. This is a 2-armed, placebo-controlled, double-blinded, crossover randomized controlled trial. The study duration is 14 weeks: 2 weeks of lead-in, 4 weeks of intervention per phase, 2 weeks of washout, and 2 weeks of follow-up. Overall, 60 healthy adults with low DF intake (<18 g [female individuals] or <22 g [male individuals] per day) were recruited in Christchurch, New Zealand, between June and December 2022. Randomly assigned participants consumed 3 (female individuals) or 4 (male individuals) slices of DRB-fortified bread per day and then placebo bread, and vice versa. The DRB-fortified bread provided 8 g (female individuals) or 10.6 g (male individuals) of total DF, whereas the placebo (a matched commercial white toast bread) provided 2.7 g (female individuals) or 3.6 g (male individuals) of total DF. Before and after each intervention phase, participants provided fecal and blood samples to assess biological responses; completed a 3-day food diary to assess usual intakes and web-based questionnaires to assess gut comfort, general and mental well-being, daily bread intake, and bowel movement via an app; underwent anthropometry and blood pressure measurements; and drank blue food dye to assess whole-gut transit time. Additionally, 25% (15/60) of the participants ingested Atmo gas-sensing capsules to assess colonic gas fermentation profile and whole-gut and regional transit time. Mean differences from baseline will be compared between the DRB and placebo groups, as well as within groups (after the intervention vs baseline). For metabolome analyses, comparisons will be made within and between groups using postintervention values. Preliminary analysis included 56 participants (n=33, 59% female; n=23, 41% male). Due to the large dataset, data analysis was planned to be fully completed by the last quarter of 2024, with full results expected to be published in peer-reviewed journals by the end of 2024. This first human study offers insights into the prospect of consuming DRB-fortified bread to effectively modulate health-promoting gut microbes, their metabolism, and DF intake in healthy adults with low DF intake. Australian New Zealand Clinical Trials Registry ACTRN12622000884707; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=383814. DERR1-10.2196/59227.

Diet, Microbiome, and Inflammation Predictors of Fecal and Plasma Short-Chain Fatty Acids in Humans

BackgroundGut microbes produce short-chain fatty acids (SCFAs), which are associated with broad health benefits. However, it is not fully known how diet and/or the gut microbiome could be modulated to improve SCFA production. ObjectivesThe objective of this study was to identify dietary, inflammatory, and/or microbiome predictors of SCFAs in a cohort of healthy adults. MethodsSCFAs were measured in fecal and plasma samples from 359 healthy adults in the United States Department of Agriculture Nutritional Phenotyping Study. Habitual and recent diet was assessed using a food frequency questionnaire and automated self-administered 24-h dietary assessment tool dietary recalls. Markers of systemic and gut inflammation were measured in fecal and plasma samples. The gut microbiome was assessed using shotgun metagenomics. Using statistics and machine learning, we determined how the abundance and composition of SCFAs varied with measures of diet, inflammation, and the gut microbiome. ResultsWe show that fecal pH may be a good proxy for fecal SCFA abundance. A higher healthy eating index for a habitual diet was associated with a compositional increase in fecal butyrate relative to acetate and propionate. SCFAs were associated with markers of subclinical gastrointestinal (GI) inflammation. Fecal SCFA abundance was inversely related to plasma lipopolysaccharide-binding protein. When we analyzed hierarchically organized diet and microbiome data with taxonomy-aware algorithms, we observed that diet and microbiome features were far more predictive of fecal SCFA abundances compared to plasma SCFA abundances. The top diet and microbiome predictors of fecal butyrate included potatoes and the thiamine biosynthesis pathway, respectively. ConclusionsThese results suggest that resistant starch in the form of potatoes and microbially produced thiamine provide a substrate and essential cofactor, respectively, for butyrate synthesis. Thiamine may be a rate-limiting nutrient for butyrate production in adults. Overall, these findings illustrate the complex biology underpinning SCFA production in the gut.This trial was registered at clinicaltrials.gov as NCT02367287.

Pain, obesity, adenosine salvage disruption, and smoking behavior mediate the effect of gut microbiota on sleep disorders: results from network Mendelian randomization and 16S rDNA sequencing.

The objective of this study is to investigate the indirect causalities between gut microbiota and sleep disorders. In stage 1, we utilized 196 gut microbiota as the exposure factor and conducted a two-sample univariable Mendelian randomization (MR) analysis on five sleep disorders: insomnia, excessive daytime sleepiness (EDS), sleep-wake rhythm disorders (SWRD), obstructive sleep apnea (OSA), and isolated REM sleep behavior disorder (iRBD). In stage 2, we validated the MR findings by comparing fecal microbiota abundance between patients and healthy controls through 16S rDNA sequencing. In stage 3, we explored the indirect pathways by which the microbiota affects sleep, using 205 gut microbiota metabolic pathways and 9 common risk factors for sleep disorders as candidate mediators in a network MR analysis. In stage 1, the univariable MR analysis identified 14 microbiota potentially influencing five different sleep disorders. In stage 2, the results from our observational study validated four of these associations. In stage 3, the network MR analysis revealed that the Negativicutes class and Selenomonadales order might worsen insomnia by increasing pain [mediation: 12.43% (95% CI: 0.47, 24.39%)]. Oxalobacter could raise EDS by disrupting adenosine reuptake [25.39% (1.84, 48.95%)]. Allisonella may elevate OSA risk via obesity promotion [36.88% (17.23, 56.54%)], while the Eubacterium xylanophilum group may lower OSA risk by decreasing smoking behavior [7.70% (0.66, 14.74%)]. Triangulation of evidence from the MR and observational study revealed indirect causal relationships between the microbiota and sleep disorders, offering fresh perspectives on how gut microbiota modulate sleep.

Replacing Cereal with Ultraprocessed Foods in Pig Diets Does Not Adverse Gut Microbiota, L-glutamate Uptake, or Serum Insulin

BackgroundUsing ultraprocessed food (UPF) to replace traditional feed ingredients offers a promising strategy for enhancing food production sustainability. ObjectiveTo analyze the impact of salty and sugary UPF on gut microbiota, amino acids uptake, and serum analytes in growing and finishing pig. MethodsThirty-six Swiss Large White male castrated pigs were assigned to 3 experimental diets: 1) standard (ST), 0% UPF; 2) 30% conventional ingredients replaced by sugary (SU) UPF; and 3) 30% conventional ingredients replaced by salty (SA) UPF. The next-generation sequencing was used to characterize the fecal microbiota. Transepithelial electrical resistance and the active uptake of selected amino acids in pig jejuna were also evaluated. Data were enriched with measurements of fecal volatile fatty acids and serum urea, minerals, and insulin. All data analyses were run in R v4.0.3. The packages phyloseq, vegan, microbiome, and microbiomeutilities were used for microbiota data analysis. The remaining data were analyzed by analysis of variance using linear mixed-effects regression models. ResultsThe UPF did not affect fecal microbiota abundance or biodiversity. The Firmicutes to Bacteroidetes ratio remained unaffected. SU-induced increase in the Anaerostipes genus suggested altered glucose metabolism, whereas SA increased the abundance of CAG-352 and p-2534-18B. No effects on fecal volatile fatty acids were observed. Assumptions of UPF negatively affecting small intestinal physiology were not supported by the measurements of transepithelial electrical resistance in pigs. Active amino acids uptake tests showed potential decrease in L-glutamate absorption in the SA compared with the SU diet. Blood serum analysis indicated no adverse effects on urea, calcium, magnesium, or potassium concentration but the SU group resulted in a lower blood serum insulin concentration at the time of blood collection. ConclusionsWhen incorporated at 30% into a standard growing finishing diet for pigs, UPF does not have detrimental effects on gut microbiota, intestinal integrity, and blood mineral homeostasis.

Fecal microbiota and concentrations of long-chain fatty acids, sterols, and unconjugated bile acids in cats with chronic enteropathy.

Feline chronic enteropathies (FCE) are common causes of chronic gastrointestinal signs in cats and include different diseases such as food-responsive enteropathy (FRE), inflammatory bowel diseases (IBD), and low-grade intestinal T-cell lymphoma (LGITL). Although changes in intestinal microbiota and fecal metabolites have been reported in dogs and humans with chronic enteropathy, research in cats has been limited. Therefore, this study aimed to evaluate the fecal microbiota and lipid-related fecal metabolites in cats with FCE to a clinically healthy comparison group (CG). A total of 34 cats with FCE (13 FRE, 15 IBD, and 6 LGITL) and 27 cats in the CG were enrolled in this study. The fecal microbiota was evaluated by the qPCR-based feline Dysbiosis Index (DI). The feline DI in cats with CE (median: 1.3, range: -2.4 to 3.8) was significantly higher (p < 0.0001) compared to CG (median: - 2.3, Range: -4.3 to 2.3), with no difference found among the FCE subgroups. The fecal abundances of Faecalibacterium (p < 0.0001), Bacteroides (p < 0.0001), Fusobacterium (p = 0.0398), Bifidobacterium (p = 0.0004), and total bacteria (p = 0.0337) significantly decreased in cats with FCE. Twenty-seven targeted metabolites were measured by gas chromatography-mass spectrometry, including long-chain fatty acids (LCFAs), sterols, and bile acids (BAs). Fecal concentrations of 5 of 12 LCFAs were significantly increased in cats with FCE compared to CG. Fecal concentrations of zoosterol (p = 0.0109), such as cholesterol (p < 0.001) were also significantly increased in cats with FCE, but those of phytosterols were significantly decreased in this group. No differences in fecal BAs were found between the groups. Although no differences were found between the four groups, the fecal metabolomic pattern of cats with FRE was more similar to that of the CG than to those with IBD or LGITL. This could be explained by the mild changes associated with FRE compared to IBD and LGITL. The study showed changes in intestinal microbiota and alteration of fecal metabolites in FCE cats compared to the CG. Changes in fecal lipids metabolites suggest a dysmetabolism of lipids, including LCFAs, sterols, and unconjugated BAs in cats with CE.

Inter-annual variation in the microplastics abundance in feces of the Baird's tapir (Tapirus bairdii) from the Selva Maya, México

Microplastics (MPs) are found in a wide range of ecosystems, from the Arctic to the deep ocean. However, there is no data on their presence in terrestrial mammals that inhabit the Selva Maya. The aim of this study is to detect the presence of MPs in the feces of the Baird's tapir (Tapirus bairdii) from the region of Calakmul, located in the Yucatan Peninsula, Mexico. We analyzed 129 fecal samples collected during 2017 and 2018, obtaining 57 and 72 samples during the rainy and dry seasons respectively. Sixty-eight percent of the samples contained 743 MPs with a mean of 19.3 ± 28.1 MPs/kg of dry weight (DW) feces in both years. An inter-annual variation in the average abundance of microplastic was observed during the two-year period (2017–2018), with a 72 % increase in these plastic particles in feces. Fourteen polymers were identified, with ethylene vinyl acetate (EVA), polypropylene (PP) and polyester (PES) being the most abundant during both years. Although the effects of MPs on the health of tapirs are not known, their presence is cause for concern. There is an urgent need for the implementation of appropriate plastic waste management programs in communities of the Selva Maya to diminish the consumption of MPs in species including humans where they pose a significant risk to health. Environmental implicationsThe use of plastics worldwide is increasing every day, so the presence of microplastics is and will continue to be a major environmental problem. It is known that contaminants can adhere to plastics, making them hazardous materials. Microplastics can contaminate remote areas such as Biosphere Reserves. Terrestrial species such as the tapir can ingest microplastics, putting their health at risk. Knowing the dispersion of microplastics is very important in order to manage them properly, taking into account their emission sources and type of polymer.

A microbiota-directed complementary food intervention in 12–18-month-old Bangladeshi children improves linear growth

Globally, stunting affects ∼150 million children under five, while wasting affects nearly 50 million. Current interventions have had limited effectiveness in ameliorating long-term sequelae of undernutrition including stunting, cognitive deficits and immune dysfunction. Disrupted development of the gut microbiota has been linked to the pathogenesis of undernutrition, providing potentially new treatment approaches. 124 Bangladeshi children with moderate acute malnutrition (MAM) enrolled (at 12-18 months) in a previously reported 3-month RCT of a microbiota-directed complementary food (MDCF-2) were followed for two years. Weight and length were monitored by anthropometry, the abundances of bacterial strains were assessed by quantifying metagenome-assembled genomes (MAGs) in serially collected fecal samples and levels of growth-associated proteins were measured in plasma. Children who had received MDCF-2 were significantly less stunted during follow-up than those who received a standard ready-to-use supplementary food (RUSF) [linear mixed-effects model, βtreatment group x study week (95% CI)=0.002 (0.001, 0.003); P=0.004]. They also had elevated fecal abundances of Agathobacter faecis, Blautia massiliensis, Lachnospira and Dialister, plus increased levels of a group of 37 plasma proteins (linear model; FDR-adjusted P<0.1), including IGF-1, neurotrophin receptor NTRK2 and multiple proteins linked to musculoskeletal and CNS development, that persisted for 6-months post-intervention. MDCF-2 treatment of Bangladeshi children with MAM, which produced significant improvements in wasting during intervention, also reduced stunting during follow-up. These results suggest that the effectiveness of supplementary foods for undernutrition may be improved by including ingredients that sponsor healthy microbiota-host co-development. This work was supported by the BMGF (Grants OPP1134649/INV-000247).

Transgenerational effects of early life stress on the fecal microbiota in mice

Stress in early life can affect the progeny and increase the risk to develop psychiatric and cardiometabolic diseases across generations. The cross-generational effects of early life stress have been modeled in mice and demonstrated to be associated with epigenetic factors in the germline. While stress is known to affect gut microbial features, whether its effects can persist across life and be passed to the progeny is not well defined. Here we show that early postnatal stress in mice shifts the fecal microbial composition (binary Jaccard index) throughout life, including abundance of eight amplicon sequencing variants (ASVs). Further effects on fecal microbial composition, structure (weighted Jaccard index), and abundance of 16 ASVs are detected in the progeny across two generations. These effects are not accompanied by changes in bacterial metabolites in any generation. These results suggest that changes in the fecal microbial community induced by early life traumatic stress can be perpetuated from exposed parent to the offspring.

#1801 Gut dysbiosis contributes to TMAO accumulation in CKD

Abstract Background and Aims Chronic kidney disease (CKD) patients face a substantial morbidity risk, especially related to cardiovascular complications. The imbalance of circulating metabolites influences inter-organ crosstalk and disease pathophysiology. In this regard, metabolites of microbial origin have gained increasing attention. Trimethylamine N-oxide (TMAO) originates from microbial Trimethylamine (TMA) metabolism and is found at high concentrations in the blood of CKD patients. A high TMAO concentration is known to be an independent risk factor for cardiovascular disease. This study aims to investigate the extent to which high concentrations of TMAO in the blood are due to increased bacterial production or are mainly a consequence of impaired renal clearance. Methods We used existing biomaterials and clinical data of a pediatric CKD cohort, consisting of patients enrolled at CKD stage G3-5, including G5 patients treated with hemodialysis (HD), as well as patients after kidney transplantation (KT) and individuals with normal kidney function. We analyzed TMAO in plasma and urine samples using LC-MS/MS and developed a novel gene targeting assay (GTA) that quantifies the abundance of the bacterial target genes (CutC, CntA) encoding for the key enzymes of microbial TMA synthesis in each fecal sample. Results Plasma TMAO levels were stage-dependently elevated in CKD, with HD patients showing the highest levels (75 ± 46 µmol/l). While urinary TMAO levels were lower in the CKD groups, TMAO/creatinine ratios and fractional excretion were not significantly different in CKD compared to controls. Fecal microbial gene abundance of both CutC and CntA genes was elevated across CKD stages and correlated with both plasma TMAO levels and eGFR. Although KT patients exhibited an eGFR range comparable to controls, they still showed higher plasma TMAO levels and elevated TMAO-associated gene abundances. In a regression analysis, this gene abundance was associated with plasma TMAO independent of eGFR in a model adjusted for age, sex, and BMI. Using a likelihood ratio test, we showed that adding fecal microbial gene abundance to the model provided a significantly better fit compared to only eGFR, age, sex, and BMI. Conclusion Our data indicate that the production of TMA by intestinal bacteria contributes significantly to the accumulation of TMAO in patients with CKD and after kidney transplantation. This finding opens the possibility for new potential interventions in the management of patients with CKD.

HIV rebound in HIV controllers is associated with a specific fecal microbiome profile.

HIV infection is associated with gut dysbiosis, and microbiome variability may affect HIV control when antiretroviral therapy (ART) is stopped. The TLR7 agonist, vesatolimod, was previously associated with a modest delay in viral rebound following analytical treatment interruption in HIV controllers (HCs). Using a retrospective analysis of fecal samples from HCs treated with vesatolimod or placebo (NCT03060447), people with chronic HIV (CH; NCT02858401) or without HIV (PWOH), we examined fecal microbiome profile in HCs before/after treatment, and in CH and PWOH. Microbiome diversity and abundance were compared between groups to investigate the association between specific phyla/species, immune biomarkers, and viral outcomes during treatment interruption. Although there were no significant differences in gut microbiome diversity between people with and without HIV, HCs, and CH shared common features that distinguished them from PWOH. there was a trend toward greater microbiome diversity among HCs. Treatment with vesatolimod reduced dysbiosis in HCs. Firmicutes positively correlated with T-cell activation, while Bacteroidetes and Euryarchaeota inversely correlated with TLR7-mediated immune activation. Specific types of fecal microbiome abundance (e.g. Alistipes putredinis) positively correlated with HIV rebound. In conclusion, variability in the composition of the fecal microbiome is associated with markers of immune activation following vesatolimod treatment and ART interruption.

Metabolome-associated psychological comorbidities improvement in irritable bowel syndrome patients receiving a probiotic

Our recent randomized, placebo-controlled study in Irritable Bowel Syndrome (IBS) patients with diarrhea or alternating bowel habits showed that the probiotic Bifidobacterium longum (BL) NCC3001 improves depression scores and decreases brain emotional reactivity. However, the involved metabolic pathways remain unclear. This analysis aimed to investigate the biochemical pathways underlying the beneficial effects of BL NCC3001 using metabolomic profiling. Patients received probiotic (1x 1010CFU, n=16) or placebo (n=19) daily for 6 weeks. Anxiety and depression were measured using the Hospital Anxiety and Depression Scale. Brain activity in response to negative emotional stimuli was assessed by functional Magnetic Resonance Imaging. Probiotic fecal abundance was quantified by qPCR. Quantitative measurement of specific panels of plasma host-microbial metabolites was performed by mass spectrometry-based metabolomics. Probiotic abundance in feces was associated with improvements in anxiety and depression scores, and a decrease in amygdala activation. The probiotic treatment increased the levels of butyric acid, tryptophan, N-acetyl tryptophan, glycine-conjugated bile acids, and free fatty acids. Butyric acid concentration correlated with lower anxiety and depression scores, and decreased amygdala activation. Furthermore, butyric acid concentration correlated with the probiotic abundance in feces. In patients with non-constipation IBS, improvements in psychological comorbidities and brain emotional reactivity were associated with an increased abundance of BL NCC3001 in feces and specific plasma metabolites, mainly butyric acid. These findings suggest the importance of a probiotic to thrive in the gut and highlight butyric acid as a potential biochemical marker linking microbial metabolism with beneficial effects on the gut-brain axis.

182 Evaluation of the effects of F18 enterotoxigenic Escherichia coli intestinal attachment in nursery pigs

Abstract Enterotoxigenic Escherichia coli (ETEC) infections are a leading cause of post-weaning diarrhea and poor performance in nursery pigs. ETEC fimbriae regulate binding to epithelial cells and subsequent intestine colonization, commonly F18 in post-weaned pigs. The objective of this study was to evaluate F18 ETEC ileal attachment in relation to growth performance and intestinal integrity and function around peak infection. Following 10 d of acclimation to a common diet, 24 individually housed, mixed sex weaned pigs [initial body weight (BW) = 5.7 ± 0.44 kg] were randomly allotted across 4 treatment groups (n=6/treatment). On day post inoculation (dpi) 0, pigs were non-inoculated (CON) or orally inoculated with 5 mL of F18 ETEC (LT, STb, Stx2, STx2e positive) at either 107 colony-forming units [CFU)/mL (LOW), 108 CFU/mL (MED] or 109 CFU/mL (HIGH). Over a 5-dpi period, fecal scores [scale: 0 (dry) – 3 (watery)] and feed intakes were measured daily. Body weights were recorded on dpi 0 and 5 to calculate average daily gain (ADG), average daily feed intake (ADFI) and gain to feed ratio (G:F). On dpi 5, all pigs were euthanized, ileal contents and feces was assessed for F18 gene abundance via PCR, and fixed ileal sections were evaluated for morphology changes, stem cell proliferation (Ki67), and F18 ETEC attachment via in situ hybridization. Further, ex vivo ileal tissue integrity and function was assessed via Ussing chambers by measuring transepithelial resistance (TER), 4.4 kDa FITC-Dextran (FD4) flux and active glucose and glutamine transport. Pig was considered the experimental unit, and data were analyzed for the fixed effects of treatment. Over this 5 dpi challenge period, ADG, ADFI, and G:F did not differ between treatments (P &amp;gt; 0.05). Compared with the CON, mean fecal scores were greatest in MED followed by the LOW and HIGH treatments (P = 0.028). Ileal pH tended to be greater in the HIGH compared with the MED, LOW and CON (7.8, 7.6, 7.5 and 7.3, respectively, P = 0.08). Compared with the CON, decreased Ct values were reported for the LOW, MED, and HIGH groups for fecal (32, 19, 18, 20, respectively; P &amp;lt; 0.001) and ileal (28, 19, 19, 18, respectively; P = 0.019) F18 gene abundances, respectively. Ileal F18 attachment was greatest in the HIGH group compared with CON, with LOW and MED being intermediate (P = 0.011). The immunohistochemistry stem cell marker Ki67 was lleast in HIGH compared with CON, LOW and MED treatments (P &amp;lt; 0.01). Ileal histology, active glucose and glutamine, TER and FD4 did not differ (P &amp;gt; 0.05). F18 attachment was negatively correlated with ileal (R = -0.706, P &amp;lt; 0.001) and fecal (R = -0.713, P &amp;lt; 0.001) F18 CT values, and positively correlated with ileal pH (R = 0.536, P &amp;lt; 0.01). In conclusion, F18 ileal attachment increased as challenge dose increased. However, at 5-dpi no effect on growth performance or ileal function and integrity was observed.

Oral bacteria relative abundance in faeces increases due to gut microbiota depletion and is linked with patient outcomes.

The detection of oral bacteria in faecal samples has been associated with inflammation and intestinal diseases. The increased relative abundance of oral bacteria in faeces has two competing explanations: either oral bacteria invade the gut ecosystem and expand (the 'expansion' hypothesis), or oral bacteria transit through the gut and their relative increase marks the depletion of other gut bacteria (the 'marker' hypothesis). Here we collected oral and faecal samples from mouse models of gut dysbiosis (antibiotic treatment and DSS-induced colitis) and used 16S ribosomal RNA sequencing to determine the abundance dynamics of oral bacteria. We found that the relative, but not absolute, abundance of oral bacteria increases, reflecting the 'marker' hypothesis. Faecal microbiome datasets from diverse patient cohorts, including healthy individuals and patients with allogeneic haematopoietic cell transplantation or inflammatory bowel disease, consistently support the 'marker' hypothesis and explain associations between oral bacterial abundance and patient outcomes consistent with depleted gut microbiota. By distinguishing between the two hypotheses, our study guides the interpretation of microbiome compositional data and could potentially identify cases where therapies are needed to rebuild the resident microbiome rather than protect against invading oral bacteria.