Abstract
BackgroundHigh serum levels of certain aromatic microbial metabolites (AMM) are associated with severity and mortality in critically ill patients. Omics-based studies suggest gut dysbiosis and reduced microbiome diversity in critical conditions. However, the landscape of gut microbial metabolites is still to be outlined, not to mention the interplay correlation between the metabolome and gut microbiome in critically ill patients. The aim of this study was to analyze the association between serum and fecal levels of AMM and compare them with the composition of gut microbiota in critically ill patients in the acute and chronic stages.MethodsIn this prospective observational pilot study, we analyzed the temporal dynamics of the gut microbiome and the AMM spectrum across two distinct subgroups—acute critical ill (ACI) patients with nosocomial pneumonia and chronically critically ill (CCI) patients (9 subjects each group)—as well as performed comparison with 23 healthy volunteers. The AMM levels for each patient were measured using GC-MS in simultaneously taken serum and fecal samples (SFS). These parameters were compared with 16S rRNA fecal microbiome profiles.ResultsThe observed proportions of bacterial taxa suggest a significant gut dysbiosis in the ACI and the CCI patients. Stronger imbalance in microbiome composition and dynamics observed in the ACI patients compared to the CCI ones resonates with a higher severity in the former group. The total levels of AMM in serum samples were higher for the ACI patients than for the CCI patients (3.7 (1.4–6.3) and 1.1 (1.0–1.6) μM, respectively; p = 0.0003). The qualitative composition of the SFS was also altered. We discovered significant associations between gut microbial taxa levels and metabolite concentrations in blood serum as well as in feces in each of the ACI and the CCI patients.ConclusionsAromatic microbial metabolite profiles in the gut and the serum are interlinked and reflect a disruption of the gut microbial community in critically ill patients.
Highlights
The importance of studying the qualitative and quantitative composition of gut microbiota in critically ill patients has been supported by a number of studies in recent years [1, 2]
Gut taxonomy dysbiosis in critically ill patients and healthy subjects The critical conditions of patients are partially reflected in their gut microbial community structure
There is a strong enrichment in microbes associated with inflammation—Enterobacteriaceae, Enterococcus, Streptococcus, and Staphylococcus, coupled with a depletion of commensal microbes
Summary
The importance of studying the qualitative and quantitative composition of gut microbiota in critically ill patients has been supported by a number of studies in recent years [1, 2]. The decay of commensal bacteria, mostly anaerobic, can lead to an overgrowth of Enterococcus [5] which is correlated with organ failure, length of stay in ICU, and mortality [2]. High serum levels of certain aromatic microbial metabolites (AMM) are associated with severity and mortality in critically ill patients. The landscape of gut microbial metabolites is still to be outlined, not to mention the interplay correlation between the metabolome and gut microbiome in critically ill patients. The aim of this study was to analyze the association between serum and fecal levels of AMM and compare them with the composition of gut microbiota in critically ill patients in the acute and chronic stages
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