Biology subjects

Dankova, H.

Publications and source records attributed to Dankova, H..

2 recordsLinked to original sources

bioRxiv2024

Evaluating Bacterial Viability in Faecal Microbiota Transplantation: A Comparative Analysis of In Vitro Cultivation and Membrane Integrity Methods

BackgroundFaecal microbiota transplantation (FMT) is a developing therapy for disorders related to gut dysbiosis. Despite its growing application, standardized protocols for FMT filtrate preparation and quality assessment remain undeveloped. The viability of bacteria in the filtrate is crucial for FMTs efficacy and for validating protocol execution. We compared two methods--in vitro cultivation and membrane integrity assessment--for their accuracy, reproducibility, and clinical applicability in measuring bacterial viability in frozen FMT stool filtrate. MethodsBacterial viability in stool filtrate was evaluated using (i) membrane integrity through fluorescent DNA staining with SYTO9 and propidium iodide, followed by flow cytometry; and (ii) culturable bacteria counts (colony-forming units, CFU) under aerobic or anaerobic conditions. ResultsWe refined the bacterial DNA staining protocol integrated with flow cytometry for stool samples. Both the membrane integrity-based and cultivation-based methods exhibited significant variability in bacterial viability across different FMT filtrates, without correlation. The cultivation-based method showed a mean coefficient of variance of 17%, ranging from 5.3% to 52.9%. Conversely, the membrane integrity approach yielded highly reproducible results, with a median coefficient of variance for viable cells of 0.9%, ranging from 8.5% to 0.04%. ConclusionBacterial viability assessment using cultivation-dependent methods produces inconsistent outcomes. In contrast, the membrane integrity method offers robust and precise data, making it a viable option for routine faecal material evaluation in FMT.

microbiology↗

bioRxiv2018

The effect of butyrate-supplemented parenteral nutrition on intestinal defence mechanisms and the parenteral nutrition-induced shift in the gut microbiota

Butyrate produced by the intestinal microbiota is essential for proper functioning of the intestinal immune system. Total dependence on parenteral nutrition (PN) is associated with numerous adverse effects, including severe microbial dysbiosis and loss of important butyrate producers. We hypothesised that a lack of butyrate produced by the gut microbiota may be compensated by its supplementation in PN mixtures. We tested whether i.v. butyrate administration would (a) positively modulate intestinal defence mechanisms and (b) counteract PN-induced dysbiosis. Male Wistar rats were randomised to chow, PN, and PN supplemented with 9 mM butyrate (PN+But) for 12 days. Antimicrobial peptides, mucins, tight junction proteins and cytokine expression were assessed by RT-qPCR. T-cell subpopulations in mesenteric lymph nodes (MLN) were analysed by flow cytometry. Microbiota composition was assessed in caecum content. Butyrate supplementation resulted in increased expression of tight junction proteins (ZO-1, claudin-7, E-cadherin), antimicrobial peptides (Defa 8, Rd5, RegIII{gamma}) and lysozyme in the ileal mucosa. Butyrate partially alleviated PN-induced intestinal barrier impairment and normalised IL-4, IL-10 and IgA mRNA expression. PN administration was associated with an increase in Tregs in MLN, which was normalised by butyrate. Butyrate increased the total number of CD4+ and decreased a relative amount of CD8+ memory T cells in MLN. Lack of enteral nutrition and PN administration led to a shift in caecal microbiota composition. Butyrate did not reverse the altered expression of most taxa but did influence the abundance of some potentially beneficial/ pathogenic genera, which might contribute to its overall beneficial effect.

physiology↗