Assessing gut microbiota disturbances for subsequent modulation remains a challenge. This study aims to evaluate the safety and efficacy of a microbiota-oriented strategy in treating patients with chronic critical illness (CCI). This single-center prospective study included chronically critically ill patients, stratified into three groups by severity of microbiota dysfunction. Three different microbiota modulation regimens including metabiotics, enteral, and anaerobic-safe systemic antibiotics were applied subsequently. Forty-three patients with chronic critical illness were included. Mild microbiota dysfunction was present in 49% patients, moderate in 19% and severe in 32%. Monitoring of biomarkers for 14 days confirmed the safety of reducing the pharmacological load in mild to moderate microbiota dysfunction. The microbiota-oriented strategy demonstrated improvements in neurological condition, a decrease in inflammation, and normalization of several hematological and biochemical parameters, without contributing to the activation of opportunistic microorganisms in the intestinal microbiota. The incidence of pneumonia in patients with CCI was reduced significantly during the 28-day observation period. The results of the pilot study suggest the potential benefits of a microbiota-oriented strategy in preventing nosocomial pneumonia in CCI patients.

Sepsis is a major cause of morbidity and mortality, but our understanding of the mechanisms underlying survival or susceptibility is limited. Here, as pathogens often subvert host defence mechanisms, we hypothesized that this might influence the outcome of sepsis. We used microbiota analysis, faecal microbiota transplantation, antibiotic treatment and caecal metabolite analysis to show that gut-microbiota-derived tryptophan metabolites including indoles increased host survival in a mouse model of Serratia marcescens sepsis. Infection in macrophage-specific aryl hydrocarbon receptor (AhR) knockout mice revealed that AhR activation induced transcriptional reprogramming in macrophages and increased bacterial clearance and host survival. However, culture supernatants from multiple bacterial pathogens inhibited AhR activation in vitro. We showed that the secreted siderophore, enterobactin, inhibited AhR activation in vitro and increased sepsis mortality in vivo. By contrast, oral or systemic tryptophan supplementation increased survival. These findings show that sepsis survival depends upon the interplay between pathogen inhibition and the activation of AhR by a microbiota-derived metabolite. Bacterial pathogens produce enterobactin, which suppresses microbiota-derived indole activation of Ahr in macrophages to inhibit bacterial clearance and increase the severity of bacterial sepsis.

Klebsiella pneumoniae (K. pneumoniae) is a major nosocomial pathogen with increasing antibiotic resistance. Treatment failures and high mortality rates in sepsis caused by K. pneumoniae are associated with difficulties in choosing an adequate antibacterial therapy in the presence of resistance to all available antibiotics, based on the results of susceptibility tests. This study aimed to identify “weak points” in the metabolism of K. pneumoniae, to be able to use these features in the future. Ten nosocomial K. pneumoniae strains were incubated with fourteen broad-spectrum antibiotics representing major drug classes. Aromatic metabolites were analyzed using gas chromatography–mass spectrometry after 24 h exposure. Phenyllactic acid (PhLA), comprising 86% of detected phenylcarboxylic acids, served as the metabolic activity marker. Antibiotics demonstrated multidirectional effects on aromatic compound metabolism. Doxycycline, nitrofurantoin, rifampicin, and tigecycline significantly suppressed metabolic activity, confirmed by decreased PhLA levels. Conversely, meropenem, cephalosporins (ceftriaxone, cefepime, cefotaxime, and ceftazidime), ciprofloxacin, and amikacin stimulated PhLA production, suggesting that bacterial metabolic activity was maintained despite the presence of antibiotics. PhLA is a promising biomarker for quantifying K. pneumoniae’s metabolic response to antibiotics. This potentially introduces a novel approach for future investigations into resistance mechanisms and has the potential to increase the effectiveness of therapies for multidrug-resistant K. pneumoniae infections by providing an additional analytical tool to traditional susceptibility testing methodologies.

Background: In the treatment of oncological diseases in children, the search for opportunities for the earlier detection of complications to improve treatment results is very important. Metabolomic studies are actively conducted to stratify different groups of patients in order to identify the most promising markers. Methods: Three groups of patients participated in this study: healthy children as a control group (n = 18), children with various malignant oncological diseases (leukemia, lymphoma, nephroblastoma, ependymoma, etc.) as patients (n = 40) without complications, and patients (n = 31) with complications (inflammatory and infectious). The mitochondrial metabolites (succinic and fumaric acids); biomarkers related to inflammation such as C-reactive protein (CRP), procalcitonin (PCT), and presepsin (PSP); and sepsis-associated aromatic metabolites, such as phenyllactic (PhLA), hydroxyphenyllactic (p-HPhLA), and hydroxyphenylacetic acids (p-HPhAA), were identified. Results: It was found that children with malignant oncological diseases had profound metabolic dysfunction compared to healthy children, regardless of the presence of systemic inflammatory response syndrome (SIRS) or sepsis. The prognostic ability of procalcitonin and presepsin for detecting sepsis was high: AUROC = 0.875, cut-off value (Youden index) = 0.913 ng/mL, and AUROC = 0.774, with cut-off value (Youden index) of 526 pg/mL, respectively. Conclusions: A significant increase in aromatic microbial metabolites and biomarkers in non-survivor patients that is registered already in the first days of the development of complications indicates the appropriateness of assessing metabolic dysfunction for its timely targeted correction.

Background. Acetyl phosphate (AcP) is a microbial intermediate involved in the central bacterial metabolism. In bacteria, it also functions as a donor of acetyl and phosphoryl groups in the nonenzymatic protein acetylation and signal transduction. In host, AcP was detected as an intermediate of the pyruvate dehydrogenase complex, and its appearance in the blood was considered as an indication of mitochondrial breakdown. In vitro experiments showed that AcP is a powerful agent of nonenzymatic acetylation of proteins. The influence of AcP on isolated mitochondria has not been previously studied. Methods. In this work, we tested the influence of AcP on the opening of the mitochondrial permeability transition pore (mPTP), respiration, and succinate dehydrogenase (SDH) activity under neutral and alkaline conditions stimulating the nonenzymatic acetylation using polarographic, cation-selective, and spectrophotometric methods. Results. It was found that AcP slowed down the opening of the mPTP by calcium ions and decreased the efficiency of oxidative phosphorylation and the activity of SDH. These effects were observed only at neutral pH, whereas alkaline pH by itself caused a decrease in these functions to a much greater extent than AcP. AcP at a concentration of 0.5–1 mM decreased the respiratory control and the swelling rate by 20–30%, while alkalization decreased them twofold, thereby masking the effect of AcP. Presumably, the acetylation of adenine nucleotide translocase involved in both the opening of mPTP and oxidative phosphorylation underlies these changes. The intermediate electron carrier phenazine methosulfate (PMS), removing SDH inhibition at the ubiquinone-binding site, strongly activated SDH under alkaline conditions and, partially, in the presence of AcP. It can be assumed that AcP weakly inhibits the oxidation of succinate, while alkalization slows down the electron transfer from the substrate to the acceptor. Conclusions. The results show that both AcP and alkalization, by promoting nonmetabolic and nonenzymatic acetylation from the outside, retard mitochondrial functions.

Background: Early diagnosis of post-operative complications is an urgent task, allowing timely prescribing of appropriate therapy and reducing the cost of patient treatment. The purpose of this study was to determine whether an integrated approach based on clinical data, along with metabolites and biomarkers, had greater predictive value than the models built on fewer data in the early diagnosis of post-operative complications after cardiac surgery. Methods: The study included patients (n = 62) admitted for planned cardiac surgery (coronary artery bypass grafting with cardiopulmonary bypass) with (n = 26) or without (n = 36) post-operative complications. Clinical and laboratory data on the first day after surgery were analyzed. Additionally, patients’ blood samples were collected before and on the first day after surgery to determine biomarkers and metabolites. Results: Multivariate PLS-DA models, predicting the presence or absence of post-operative complications, were built using clinical data, concentrations of metabolites and biomarkers, and the entire data set (ROC-AUC = 0.80, 0.71, and 0.85, respectively). For comparison, we built univariate models using the EuroScore2 and SOFA scales, concentrations of lactate, the dynamic changes of 4-hydroxyphenyllactic acid, and the sum of three sepsis-associated metabolites (ROC-AUC = 0.54, 0.79, 0.62, 0.58, and 0.70, respectively). Conclusions: The proposed complex model using the entire dataset had the best characteristics, which confirms the expediency of searching for new predictive models based on a variety of factors.

A review on the quantitative determination of aromatic monocarboxylic acids (AMCAs), intermediates in the metabolism of the proteinogenic amino acids phenylalanine and tyrosine, in body fluids is presented. The importance of these compounds as potential diagnostic low-molecular-weight biomarkers of some human diseases is described. The main methodical features of current practical solutions in the field of highly sensitive screening of AMCAs in body fluids using chromatography-mass spectrometry and other methods actively used in clinical laboratory analysis are considered. Special attention is paid to the prospects of developing portable tools for therapeutic monitoring of the compounds of interest in biological fluids. The bibliography includes 108 references.

Background: Research has shown the multiple actions of curcumin on different cell systems, including enzymes and mitochondria. The detected effects of curcumin on mitochondria are diverse, ranging from protective to toxic. Objectives: In this present work, the influence of curcumin, as well as cinnamic acid, which is a microbial metabolite and a possible product of the microbial breakdown of curcumin, on isolated mitochondria, was investigated. Methods: Membrane potential, swelling, respiration, and calcium retention capacity were studied using selective electrodes, fluorescence and spectral methods. Results: It was found that curcumin at low concentrations (10–20 μM) activated the opening of the calcium-dependent permeability transition pore (mPTP) and decreased the calcium retention capacity and threshold concentrations necessary for the mPTP opening. Moreover, curcumin caused a concentration-dependent stepwise decrease in the membrane potential, accompanied by the activation of respiration and a decrease in oxidative phosphorylation, which indicates that curcumin is a typical mitochondrial uncoupler. The uncoupling effect strongly depended on the concentration of curcumin, which also increased, stepwise, from weak uncoupling at 25 µM to complete uncoupling at 75–100 µM. Cinnamic acid had similar effects, with the exception of the depolarizing effect, at concentrations that were an order of magnitude higher. Conclusions: Presumably, the uncoupling action of curcumin is a priming event that modulates any energy- and redox-dependent mitochondrial functions, from positive stimulation to toxic disorder. This effect can also underlie the curcumin-induced changes in different cellular processes and be achieved by targeted delivery of curcumin to certain cells, bypassing the microbiota.

Postoperative complications in cardiovascular surgery remain an important unresolved problem, in particular in patients with aortic aneurysm. The role of the altered microbiota in such patients is of great interest. The aim of this pilot study was to determine whether the development of postoperative complications in patients with aortic aneurysm is related with initial or acquired disorders of microbiota metabolism by monitoring the level of some aromatic microbial metabolites (AMMs) circulating in the blood before the surgery and in the early postoperative period. The study comprised patients with aortic aneurysm (n = 79), including patients without complications (n = 36) and patients with all types of complications (n = 43). The serum samples from the patients were collected before and 6 h after the end of the surgery. The most significant results were obtained for the sum of three sepsis-associated AMMs. This level was higher before the surgery in comparison with that of healthy volunteers (n = 48), p < 0.001, and it was also higher in the early postoperative period in patients with all types of complications compared to those without complications, p = 0.001; the area under the ROC curve, the cut-off value, and the odds ratio were 0.7; 2.9 µmol/L, and 5.5, respectively. Impaired microbiota metabolism is important in the development of complications after complex reconstructive aortic surgery, which is the basis for the search for a new prevention strategy.

Post-COVID-19 syndrome is a complex of different symptoms, which results in a multisystemic impairment after the suffering from COVID-19 infection. The aim of the study was to reveal the clinical, laboratory, and gut disorders in patients with post-COVID-19 syndrome (n = 39) before and after taking part in the 14-day complex program of rehabilitation. A complete blood count, coagulation test, blood chemistry, biomarkers, and metabolites in serum samples, and gut dysbiosis were revealed in patients on the day of admission and after 14-day rehabilitation, in comparison with the variables of healthy volunteers (n = 48) or with reference ranges. On the day of discharge, patients noted an improvement in respiratory function, general well-being, and mood. At the same time, the levels of some metabolic (4-hydroxybenzoic, succinic, fumaric acids) and inflammatory (interleukin-6) variables, which were increased on admission, did not reach the level of healthy people during the rehabilitation program. Taxonomy disbalance was observed in patients' feces, namely, a high level of total bacterial mass, a decrease in the number of Lactobacillus spp., and an increase in pro-inflammatory microorganisms. The authors suggest that the post-COVID-19 rehabilitation program should be personalized, considering the patient's state together with not only the baseline levels of biomarkers, but also with the individual taxonomy of the gut microbiota.

The human microbiota produces metabolites that can enter the bloodstream and exert systemic effects on various functions in both healthy and pathological states. We have studied the participation of microbiota-related metabolites in bacterial infection by examining their influence on the activity of cyclooxygenase (COX) as a key enzyme of inflammation. The influence of aromatic microbial metabolites, derivatives of phenylalanine (phenylpropionic acid, PPA), tyrosine (4-hydroxyphenyllactic acid, HPLA), and tryptophan (indolacetic acids, IAA), the concentrations of which in the blood change notably during sepsis, was evaluated. Also, the effect of itaconic acid (ITA) was studied, which is formed in macrophages under the action of bacterial lipopolysaccharides (LPS) and appears in the blood in the early stages of infection. Metabiotic acetyl phosphate (AcP) as a strong acetylating agent was also tested. The activity of COX was measured via the TMPD oxidation colorimetric assay using the commercial pure enzyme, cultured healthy monocytes, and the human acute monocytic leukemia cell line THP-1. All metabolites in the concentration range of 100–500 μM lowered the activity of COX. The most pronounced inhibition was observed on the commercial pure enzyme, reaching up to 40% in the presence of AcP and 20–30% in the presence of the other metabolites. On cell lysates, the effect of metabolites was preserved, although it significantly decreased, probably due to their interaction with other targets subject to redox-dependent and acetylation processes. The possible contribution of the redox-dependent action of microbial metabolites was confirmed by assessing the activity of the enzyme in the presence of thiol reagents and in model conditions, when the COX-formed peroxy intermediate was replaced with tert-butyl hydroperoxide (TBH). The data show the involvement of the microbial metabolites in the regulation of COX activity, probably due to their influence on the peroxidase activity of the enzyme.

Ароматические, летучие жирные и дикарбоновые кислоты относятся к низкомолекулярным микробным и митохондриальным метаболитам, поэтому их одновременный скрининг в биологических образцах, включая спинномозговую жидкость, является перспективным решением важной задачи – своевременной дифференциальной диагностики различных заболеваний и патологий, в частности, связанных с нарушением работы центральной нервной системы. Существует необходимость разработки чувствительной методики совместного определения данных соединений, так как чаще всего они присутствуют в биологических образцах в следовых количествах. Сыворотка крови и спинномозговая жидкость являются сложными матрицами, в состав которых входят различные соединения. Для выделения и концентрирования ароматических, дикарбоновых и летучих жирных кислот в настоящей работе применяли традиционную жидкостно-жидкостную экстракцию, модифицированную на стадии дериватизации: органический экстрагент не упаривали, а проводили дериватизацию непосредственно в объеме диэтилового эфира. При анализе учитывали разную летучесть и полярность соединений, поэтому проводили дериватизацию при умеренном нагревании (60 °С) с применением различных силилирующих агентов. В зависимости от определяемых производных выбрали условия анализа методом газовой хроматомасс-спектрометрии, обеспечивающие повышение чувствительности к целевым соединениям и полное газохроматографическое разделение всех аналитов за приемлемое время. Для оценки применимости выбранных условий анализа определяли аналитические характеристики в модельных растворах и в сыворотке крови здоровых доноров. Для всех условий анализа соблюдается линейность в клинически значимом диапазоне, нижние пределы количественного определения находятся в диапазоне от 0.06 до 0.9 мкмоль л-1, что позволило провести анализ образцов спинномозговой жидкости пациентов нейрохирургического профиля (n = 6).

Aromatic, short-chain fatty and dicarboxylic acids are low-molecular-weight microbial and mitochondrial metabolites; therefore, their simultaneous screening in biological samples, including cerebrospinal fluid, is a promising solution to an important problem – the timely differential diagnosis of various diseases and pathologies, in particular, those associated with the disruption of the central nervous system. There is a need in developing a sensitive method for the simultaneous determination of these compounds, because they are most often present in biological samples in trace amounts. Blood serum and cerebrospinal fluid are complex matrices including various compounds. Aromatic, short-chain fatty and dicarboxylic acids were isolated and preconcentrated in the present study by traditional liquid–liquid extraction modified at the derivatization stage: the organic extractant was not evaporated and derivatization was carried out directly in the volume of diethyl ether. The different volatilities and polarities of the compounds was taken into account; therefore, derivatization was carried out with moderate heating (60°C) using various silylating reagents. Depending on the type of silyl derivatives, we set the analysis mode of gas chromatography–mass spectrometry method in order to achieve an acceptable analysis time, increase sensitivity to target compounds, and carry out a complete gas chromatographic separation of all analytes. To assess the applicability of the developed conditions, analytical characteristics were determined in model solutions and in the blood serum of healthy donors. For all the developed analysis conditions, linearity was observed in a clinically significant range; the lower limits of quantitation were in the range from 0.06 to 0.9 μmol L –1 , which made it possible to analyze samples of the cerebrospinal fluid of neurosurgical patients ( n = 6).

The profile of and dynamic concentration changes in tyrosine, phenylalanine, and tryptophan metabolites in blood are of great interest since they could be considered potential biomarkers of different disorders. Some aromatic metabolites, such as 4-hydroxyphenyllactic, 4-hydroxyphenylacetic, phenyllactic, and 4-hydroxybenzoic acids have previously demonstrated their diagnostic significance in critically ill patients and patients with post-COVID-19 syndrome. In this study, a sensitive method, including serum protein precipitation with methanol and ultra-high-pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) detection, was developed and validated for six phenyl- and five indole-containing acids in human serum. The liquid–liquid extraction was also examined, but it demonstrated unsatisfactory results based on analyte recoveries and the matrix effect. However, the recoveries for all analytes reached 100% and matrix effects were not observed using protein precipitation. This made it possible to use deionized water as a blank matrix. The lower limits of quantitation (LLOQs) were from 0.02 to 0.25 μmol/L. The validated method was used for the analysis of serum samples of healthy volunteers (n = 48) to reveal the reference values of the target analytes. The concentrations of the most clinically significant metabolite 4-hydroxyphenyllactic acid, which were revealed using UPLC-MS/MS and a previously developed gas chromatography-mass spectrometry method, were completely comparable. The proposed UPLC-MS/MS protocol can be used in the routine clinical practice of medical centers.

Pancreatic cancer (PC) has the highest mortality rate of all major cancers in the world despite improvements in clinical care and an understanding of the biology of pancreatic cancer. A study of 64 patients with verified pancreatic cancer who underwent surgery was included. Sampling was carried out at three points: before surgery and on days 1–3 after surgery and 5–7 days after surgery. Drainage fluid collection was taken from the drains installed intraoperatively one day after surgery. Tyrosine and phenylalanine metabolites and two mitochondrial metabolites, namely succinic and fumaric acids, were identified and quantified by GC-MS in the serum of healthy donors and patients. Differences in the metabolomic profile were found between the patients and healthy people. A statistically significant decrease in the level of p-hydroxyphenyllactic acid (p-HPhLA), the amount of sum 3 sepsis-associated metabolites (Σ 3AMM), as well as fumaric and succinic acids in patients was observed. It was also noted that p-hydroxyphenyllactic acid in the preoperative period may be considered as a predictor of complications and longer postoperative recovery.

High concentration of sepsis-associated aromatic microbial metabolites (AMM) stands as a prognostically unfavorable factor, indicating the progression of multiple organ dysfunction and an increased risk of death in patients with sepsis and septic shock. This study is based on a hypothesis that excess of sepsis-associated AMM in patients with sepsis is caused by metabolic alterations (dysfunction) in the intestinal microbiota.The aim of this study was to compare the potential of normobiota and pathobiota to bio-transform sepsis-associated metabolites of aromatic amino acids tyrosine and phenylalanine, such as phenyllactic acid(PhLA) and 4-hydroxyphenyllactic acid (4-HPhLA).Materials and methods. Samples of intestinal contents of patients with septic shock (N=10, pathobiota) and healthy volunteers (N=9, normobiota) were placed in test tubes with the omnipurpose thioglycol medium. The clinical model of excessive inflow of sepsis-associated AMM into the intestine (for example, from blood or sites of inflammation) was reproduced in the in vitro experiment by adding PhLA or 4-HPhLA in clinically significant concentrations (25 mkM) into each test tube with pathobiota and normobiota. After incubation in a thermostat (37°, 24 hours), AMМ concentrations were measured in the samples with pathobiota and normobiota using GC-MS analysis.Results. Concentration of AMM decreased within 24 hours in the tubes with normobiota after PhLA or 4-HPhLA were added. In the tubes with pathobiota, no decrease in AMM concentrations was documented after loading with PhLA or 4-HPhLA. Concentrations of PhLA (P=0.002) and 4-HPhLA (P0.001) were statistically significantly higher in pathobiota samples compared to normobiota.Conclusion. The in vitro experiment demonstrates that after excessive load with sepsis-associated metabolites (PhLA, 4-HPhLA), the microbiota of healthy people is capable to bio-transform such metabolites to the end products of microbial metabolism, while pathobiota of septic patients exhibits altered biotransformational potential. This data demonstrate that microbiota dysfunction may contribute to the pathogenesis of sepsis.

Thanks to modern technical solutions and advances in the field of metabolomic research, it has become possible to search for new biomarkers among low-molecular compounds, including microbial origin. In intensive care, the most urgent and unresolved problem is the syndrome of systemic inflammatory reaction, one way or another associated with bacteria, for example, complications of artificial lung ventilation, postoperative complications, attachment of multiple organ failure (sepsis), etc. Therefore, among a wide range of small molecules, metabolites of aromatic amino acid (tyrosine, phenylalanine) are of the greatest interest, since the metabolic pathways leading to their accumulation or disposal are closely interrelated in the human body with the human microbiota. Over the past two decades, in clinical studies, results of the search for metabolites of microbial origin using GC-MS were obtained in various groups of critical patients with pneumonia, abdominal sepsis, septic shock, infection complication in cardio surgery, neuro surgery, etc. The data indicate a high diagnostic and prognostic significance of some aromatic microbial metabolites (AMM), such as 4-hydroxyphenyl lactic acid (HPhLA), 4-hydroxyphenyl acetic acid (HPhAA), phenyllactic acid (PhAA). Serum AMM level in sepsis was not inferior and even had advantages over such well-known biomarkers as PCT or lactate, and was comparable in importance to multi-parametric severity scales such as SOFA. The use of AMM to predict the outcome of patients admitted to the intensive care unit is no less reliable than the widespread multi-parametric APACHE II scale. In vitro experimental studies have confirmed the ability of human microbiota bacteria to produce and consume the abovementioned, clinically significant aromatic metabolites; a decrease in the biodiversity of the microbiota and its metabolic function leads to an excess of AMM in the blood. In intensive care, AMM can be used to assess the severity of patients’ condition and the risk of death, to predict complications in big surgery (abdominal, cardiac, neurosurgery, etc.), as well as to monitor the effect of treatment. Today, the serum level of AMM is determined using GC-MS, HPLC-MS, etc. For widespread implementation in intensive care units, an accessible express method is needed, which will help improve results in patients with life-threatening diseases and sepsis.

In patients with severe brain damage, the severity of the course/outcome of a chronic critical condition is associated with dysfunction of the intestinal microbiota, which can be assessed by the level of microbial metabolites circulating in the blood.The purpose of the study. To establish a connection between the dynamics of a chronic critical condition developed as a result of severe brain damage and microbiota dysfunction.Patients and methods. The study included 83 patients in chronic critical state (CCS) with the consequences of ischemic/ hemorrhagic stroke (n = 34), traumatic brain injury (n = 18), hypoxic brain damage (n = 7), neurosurgical interventions (n = 7), meningitis (n = 3); and 30 healthy people (control group). To assess the neurological status in dynamics, the stroke scales of the National Institutes of Health (NIHSS), the FOUR, Rankin scales, and the Rivermead Mobility Index were used. The taxonomic composition of the microbiota was evaluated by 16S rRNA sequencing and PCR. Biomarkers (by ELISA Kit) and aromatic microbial metabolites (by GC-MS) were monitored twice a week.Results. The peculiarities of the taxonomic composition of the intestinal microbiota in long-term ill patients with brain damage, the predominance of conditionally pathogenic facultative anaerobes (Klebsiella spp., Proteus spp., Staphylococcus aureus) over the pool of strict anaerobes were revealed. The relationship between the dynamics of microbial metabolites in blood and gut of patients with the course and outcome of the disease has been established. Patients with positive clinical dynamics of CCS were characterized by a stable level or decrease in microbial metabolites during treatment. In the group of patients with negative clinical dynamics, an increase in the level of microbial metabolites, especially hydroxylated phenyl carboxylic acids, was revealed.Conclusion. In patients with brain damage, the levels of microbial metabolites circulating in the blood (p-hydroxyphenylacetic, phenyl-lactic, p-hydroxyphenyl-lactic acids) reflect the degree of microbiota dysfunction and the severity of the course of CCS, which is of prognostic importance.

Increasing evidence suggests that gut dysbiosis is associated with coronavirus disease 2019 (COVID-19) infection and may persist long after disease resolution. The excessive use of antimicrobials in patients with COVID-19 can lead to additional destruction of the microbiota, as well as to the growth and spread of antimicrobial resistance. The problem of bacterial resistance to antibiotics encourages the search for alternative methods of limiting bacterial growth and restoring the normal balance of the microbiota in the human body. Bacteriophages are promising candidates as potential regulators of the microbiota. In the present study, two complex phage cocktails targeting multiple bacterial species were used in the rehabilitation of thirty patients after COVID-19, and the effectiveness of the bacteriophages against the clinical strain of Klebsiella pneumoniae was evaluated for the first time using real-time visualization on a 3D Cell Explorer microscope. Application of phage cocktails for two weeks showed safety and the absence of adverse effects. An almost threefold statistically significant decrease in the anaerobic imbalance ratio, together with an erythrocyte sedimentation rate (ESR), was detected. This work will serve as a starting point for a broader and more detailed study of the use of phages and their effects on the microbiome.