Microbiome in Critical illness: An Unconventional and Unknown Ally

Gut microbiome-brain-cirrhosis axis

Cirrhosis is characterized by inflammation, degeneration, and fibrosis of liver tissue. Along with being the most common cause of liver failure and liver transplant, cirrhosis is a significant risk factor for several neuropsychiatric conditions. The most common of these is HE, which is characterized by cognitive and ataxic symptoms, resulting from the buildup of metabolic toxins with liver failure. However, cirrhosis patients also show a significantly increased risk for neurodegenerative diseases such as Alzheimer and Parkinson diseases, and for mood disorders such as anxiety and depression. In recent years, more attention has been played to communication between the ways the gut and liver communicate with each other and with the central nervous system, and the way these organs influence each other's function. This bidirectional communication has come to be known as the gut-liver-brain axis. The gut microbiome has emerged as a key mechanism affecting gut-liver, gut-brain, and brain-liver communication. Clinical studies and animal models have demonstrated the significant patterns of gut dysbiosis when cirrhosis is present, both with or without concomitant alcohol use disorder, and have provided compelling evidence that this dysbiosis also influences the cognitive and mood-related behaviors. In this review, we have summarized the pathophysiological and cognitive effects associated with cirrhosis, links to cirrhosis-associated disruption of the gut microbiome, and the current evidence from clinical and preclinical studies for the modulation of the gut microbiome as a treatment for cirrhosis and associated neuropsychiatric conditions.

Modulation of chicken gut microbiota for enhanced productivity and health: A review

Microbiota in the digestive tract has become an interesting topic for researchers in recent years. The profile of chicken digestive tract microbiota and its relationship with health and production efficiency have become basic data for modulating the diversity and abundance of the digestive tract microbiota. This article reviews the techniques used to analyze the diversity, role, and function of the gastrointestinal microbiota and the mechanisms by which they are modulated. The gut microbiota plays an important role in animal production, especially during feed digestion and animal health, because it interacts with the host against pathogens. Feed modulation can be a strategy to modulate gut composition and diversity to increase production efficiency by improving growth conditions.

Impact of various solutions on the oral health status of critically ill patients

Oral care is a crucial challenge of nursing care in orally intubated patients. Oropharyngeal colonization with microorganisms is probably the first step in the pathogenesis of most bacterial pulmonary infections. This study aimed to investigate the effect of different oral care solutions on the oral health status of critically ill patients. We conducted a quasi-experimental study involving a convenience sample of 60 adult orally intubated patients, distributed equally into three groups: 20 patients received 0.12% chlorhexidine gluconate (CHX) solution as an oral rinse; 20 patients received 0.1% hexetidine (HEX) solution as an oral rinse; and a control group of 20 patients received routine hospital oral care with 0.9% normal saline (NS) solution. Oropharyngeal and tracheal cultures were obtained from patients within 24-48 h of admission, before the administration of topical oral antimicrobial solutions and then repeated on day 4 and day 7 after the oral solutions. The study revealed that CHX has a more powerful effect than HEX and NS in improving the oral mucosa and decreasing colonization of both the oropharynx and trachea. On day 7, the improvements were statistically significant in the CHX group and the HEX group (P = 0.02 and P = 0.03, respectively), but not in the NS group. This research confirms the effect of CHX and HEX in lowering the risk of tracheal and oropharyngeal colonization, and recommends the use of a CHX solution as oral mouth care in critically ill patients.

Practical Lessons on Antimicrobial Therapy for Critically Ill Patients

Sepsis stands as a formidable global health challenge, with persistently elevated mortality rates in recent decades. Each year, sepsis not only contributes to heightened morbidity but also imposes substantial healthcare costs on survivors. This narrative review aims to highlight the targeted measures that can be instituted to alleviate the incidence and impact of sepsis in intensive care. Here we discuss measures to reduce nosocomial infections and the prevention of equipment and patient colonisation by resilient pathogens. The overarching global crisis of bacterial resistance to newly developed antimicrobial agents intensifies the imperative for antimicrobial stewardship and de-escalation. This urgency has been accentuated in recent years, notably during the COVID-19 pandemic, as high-dose steroids and opportunistic infections presented escalating challenges. Ongoing research into airway colonisation's role in influencing disease outcomes among critically ill patients underscores the importance of tailoring treatments to disease endotypes within heterogeneous populations, which are important lessons for intensivists in training. Looking ahead, the significance of novel antimicrobial delivery systems and drug monitoring is poised to increase. This narrative review delves into the multifaceted barriers and facilitators inherent in effectively treating critically ill patients vulnerable to nosocomial infections. The future trajectory of intensive care medicine hinges on the meticulous implementation of vigilant stewardship programs, robust infection control measures, and the continued exploration of innovative and efficient technological solutions within this demanding healthcare landscape.

Crosstalk Between the Nervous System and Systemic Organs in Acute Brain Injury

Organ crosstalk is a complex biological communication between distal organs mediated via cellular, soluble, and neurohormonal actions, based on a two-way pathway. The communication between the central nervous system and peripheral organs involves nerves, endocrine, and immunity systems as well as the emotional and cognitive centers of the brain. Particularly, acute brain injury is complicated by neuroinflammation and neurodegeneration causing multiorgan inflammation, microbial dysbiosis, gastrointestinal dysfunction and dysmotility, liver dysfunction, acute kidney injury, and cardiac dysfunction. Organ crosstalk has become increasingly popular, although the information is still limited. The present narrative review provides an update on the crosstalk between the nervous system and systemic organs after acute brain injury. Future research might help to target this pathophysiological process, preventing the progression toward multiorgan dysfunction in critically ill patients with brain injury.

Gut-Kidney-Heart: A Novel Trilogy

The microbiota represents a key factor in determining health and disease. Its role in inflammation and immunological disorders is well known, but it is also involved in several complex conditions, ranging from neurological to psychiatric, from gastrointestinal to cardiovascular diseases. It has recently been hypothesized that the gut microbiota may act as an intermediary in the close interaction between kidneys and the cardiovascular system, leading to the conceptualization of the "gut-kidney-heart" axis. In this narrative review, we will discuss the impact of the gut microbiota on each system while also reviewing the available data regarding the axis itself. We will also describe the role of gut metabolites in this complex interplay, as well as potential therapeutical perspectives.

The Potential of Gut Microbiota in Prediction of Stroke-Associated Pneumonia

BACKGROUND

Stroke-associated pneumonia (SAP) is a common stroke complication, and the changes in the gut microbiota composition may play a role. Our study aimed to evaluate the predictive ability of gut microbiota for SAP.

METHODS

Acute ischemic stroke patients were prospectively enrolled and divided into two groups based on the presence or absence of SAP. The composition of gut microbiota was characterized by the 16S RNA Miseq sequencing. The gut microbiota that differed significantly between groups were incorporated into the conventional risk scores, the Acute Ischemic Stroke-Associated Pneumonia Score (AIS-APS), and the Age, Atrial fibrillation, Dysphagia, Sex, Stroke Severity Score (A2DS2). The predictive performances were assessed in terms of the area under the curve (AUC), the Net Reclassification Improvement (NRI), and the Integrated Discrimination Improvement (IDI) indices.

RESULTS

A total of 135 patients were enrolled, of whom 43 had SAP (31%). The short-chain fatty acids (SCFAs)-producing bacteria, such as Bacteroides, Fusicatenibacter, and Butyricicoccus, were decreased in the SAP group. The integrated models showed better predictive ability for SAP (AUC = 0.813, NRI = 0.333, p = 0.052, IDI = 0.038, p = 0.018, for AIS-APS; AUC = 0.816, NRI = 0.575, p < 0.001, IDI = 0.043, p = 0.007, for A2DS2) in comparison to the differential genera (AUC = 0.699) and each predictive score (AUCAISAPS = 0.777; AUCA2DS2 = 0.777).

CONCLUSIONS

The lower abundance of SCFAs-producing gut microbiota after acute ischemic stroke was associated with SAP and may play a role in SAP prediction.

Ratio of procalcitonin/Simpson's dominance index predicted the short-term prognosis of patients with severe bacterial pneumonia

Objective

The aim of this study was to explore the predictive value of the ratio of procalcitonin (PCT) in serum to Simpson's dominance index (SDI) in bronchoalveolar lavage fluid (BALF), in short-term prognosis of patients with severe bacterial pneumonia (SBP).

Methods

This is a retrospective review of case materials of 110 patients with SBP who selected BALF metagenomic next-generation sequencing technique in the intensive care unit (ICU) of the Affiliated Hospital of Yangzhou University from January 2019 and July 2022. Based on the acute physiology and chronic health status score II, within 24 h after admission to the ICU, patients were divided into a non-critical group (n = 40) and a critical group (n = 70). Taking death caused by bacterial pneumonia as the endpoint event, the 28-day prognosis was recorded, and the patients were divided into a survival group (n = 76) and a death group (n = 34). The SDI, PCT, C-reactive protein (CRP), PCT/SDI, and CRP/SDI were compared and analyzed.

Results

Compared with the non-critical group, the critical group had a higher PCT level, a greater PCT/SDI ratio, a longer ventilator-assisted ventilation time (VAVT), and more deaths in 28 days. Compared with the survivors, the death group had a higher PCT level, a lower SDI level, and a greater PCT/SDI ratio. The SDI level was significantly negatively correlated with the VAVT (r = -0.675, p < 0.05), while the PCT level, ratio of PCT/SDI, and ratio of CRP/SDI were remarkably positively correlated with VAVT (r = 0.669, 0.749, and 0.718, respectively, p < 0.05). The receiver operating characteristic (ROC) curves analysis showed that the area under ROC curves of PCT/SDI predicting patient death within 28 days was 0.851, followed by PCT + SDI, PCT, SDI, and CRP/SDI (0.845, 0.811, 0.778, and 0.720, respectively). The sensitivity and specificity of PCT/SDI for predicting death were 94.1% and 65.8%, respectively, at the optimal value (11.56). Cox regression analysis displayed that PCT/SDI (HR = 1.562; 95% CI: 1.271 to 1.920; p = 0.039) and PCT (HR = 1.148; 95% CI: 1.105 to 1.314; p = 0.015) were independent predictors of death in patients.

Conclusion

The ratio of PCT/SDI was a more valuable marker in predicting the 28-day prognosis in patients with SBP.

The Role of Cold Atmospheric Plasma in Wound Healing Processes in Critically Ill Patients

Critically ill patients are at risk of skin wounds, which reduce their quality of life, complicate their pharmacological regimens, and prolong their hospital stays in intensive care units (ICUs), while also increasing overall mortality and morbidity rates. Cold atmospheric plasma (CAP) has been proposed as a viable option for many biological and medical applications, given its capacity to reduce wound bacterial contamination and promote wound healing. The aim of this narrative review is to describe how CAP works and its operating mechanisms, as well as reporting its possible applications in critical care settings. The success of CAP in the treatment of wounds, in particular, bedsores or pressure sores, presents an innovative path in the prevention of nosocomial infections and an opportunity of reducing the negative implications of these diseases for the NHS. This narrative review of the literature was conducted following the 'Scale for the Assessment of Narrative Review Articles' (SANRA) methodology. Previous literature highlights three biological effects of plasma: inactivation of a wide range of microorganisms, including those that are multi-drug-resistant; increased cell proliferation and angiogenesis with a shorter period of plasma treatment; and apoptosis stimulation with a longer and more intensive treatment. CAP is effective in many areas of the medical field, with no significant adverse effects on healthy cells. However, its use can produce potentially serious side effects and should, therefore, be used under expert supervision and in appropriate doses.

The Impact of Smoking on Microbiota: A Narrative Review

Cigarette smoke is a classic risk factor for many diseases. The microbiota has been recently indicated as a new, major player in human health. Its deregulation-dysbiosis-is considered a new risk factor for several illnesses. Some studies highlight a cross-interaction between these two risk factors-smoke and dysbiosis-that may explain the pathogenesis of some diseases. We searched the keywords "smoking OR smoke AND microbiota" in the title of articles on PubMed^®, UptoDate^®, and Cochrane^®. We included articles published in English over the last 25 years. We collected approximately 70 articles, grouped into four topics: oral cavity, airways, gut, and other organs. Smoke may impair microbiota homeostasis through the same harmful mechanisms exerted on the host cells. Surprisingly, dysbiosis and its consequences affect not only those organs that are in direct contact with the smoke, such as the oral cavity or the airways, but also involve distant organs, such as the gut, heart, vessels, and genitourinary tract. These observations yield a deeper insight into the mechanisms implicated in the pathogenesis of smoke-related diseases, suggesting a role of dysbiosis. We speculate that modulation of the microbiota may help prevent and treat some of these illnesses.

Multidrug-Resistant and Extended-Spectrum β-Lactamase Gram-Negative Bacteria in Bilateral Lung Transplant Recipients: Incidence, Risk Factors, and In-Hospital Mortality

BACKGROUND

In recent decades, the incidence of multidrug-resistant (MDR) and extended-spectrum β-lactamase (ESBL) gram-negative (GN) bacteria has increased progressively among lung transplantation (LT) recipients. A prompt diagnosis, prevention, and management of these pathogens remain the cornerstone for successful organ transplantation.

RESEARCH QUESTION

What are the incidence of MDR and ESBL GN bacteria within the first 30 days after LT and related risk of in-hospital mortality? What are the potential clinical predictors of isolation of MDR and ESBL GN bacteria?

STUDY DESIGN AND METHODS

All consecutive LT recipients admitted to the ICU of the University Hospital of Padua (February 2016-December 2021) were screened retrospectively. Only adult patients undergoing the first bilateral LT and not requiring invasive mechanical ventilation, extracorporeal membrane oxygenation, or both before surgery were included. MDR and ESBL GN bacteria were identified using in vitro susceptibility tests and were isolated from the respiratory tract, blood, urine, rectal swab, or surgical wound or drainage according to a routine protocol.

RESULTS

One hundred fifty-three LT recipients were screened, and 132 were considered for analysis. Median age was 52 years (interquartile range, 41-60 years) and 46 patients (35%) were women. MDR and ESBL GN bacteria were identified in 45 patients (34%), and 60% of patients demonstrated clinically relevant infection. Pseudomonas aeruginosa (n = 22 [49%]) and Klebsiella pneumoniae (n = 17 [38%]) were frequently isolated after LT from the respiratory tract (n = 21 [47%]) and multiple sites (n = 18 [40%]). Previous recipient-related colonization (hazard ratio [HR], 2.48 [95% CI, 1.04-5.90]; P = .04) and empirical exposure to broad-spectrum antibiotics (HR, 6.94 [95% CI, 2.93-16.46]; P < .01) were independent predictors of isolation of MDR and ESBL GN bacteria. In-hospital mortality of the MDR and ESBL group was 27% (HR, 6.38 [95% CI, 1.98-20.63]; P < .01).

INTERPRETATION

The incidence of MDR and ESBL GN bacteria after LT was 34%, and in-hospital mortality was six times greater. Previous recipient-related colonization and empirical exposure to broad-spectrum antibiotics were clinical predictors of isolation of MDR and ESBL GN bacteria.

Cellular Immuno-Profile in Septic Human Host: A Scoping Review

Simple Summary

Septic shock is a life-threatening disease caused by a dysregulated host response to infection, affecting millions of people every year and killing more than 25% directly despite advances in modern medicine. This pathology is characterized by apoptosis-induced depletion of immune cells and immunodepression. Many alterations in the expression of surface markers of neutrophils and monocytes have been described in septic patients. There is no specific treatment but the early identification and diagnosis of the pathology as well as timely treatment can greatly improve patient outcomes. The aim of this study was to inspect the recently published literature to inform the clinician about the most up-to-date techniques for the study of immune cell phenotypes and on the function of leukocytes of extracorporeal and non-blood purification treatments proposed for sepsis were also analyzed. The most important alteration observed in septic neutrophils is the activation of a survival program capable of resisting apoptotic death. As regards adaptive immunity, sepsis-induced apoptosis leads to lymphopenia in patients with septic shock and this process involves all types of T cells (CD4, CD8 and Natural Killer), except for regulatory T cells, favoring immunosuppression. Several promising therapies that target the host’s immune response to sepsis are currently under evaluation.

Abstract

Innate and adaptive immune system cells play a critical role in the host response to sepsis. Sepsis is a life-threatening disease characterized by apoptosis-induced depletion of immune cells and immunodepression, which contribute to morbidity and mortality. Many alterations in the expression of surface markers of neutrophils and monocytes have been described in septic patients. The aim of this study was to inspect the recently published literature to inform the clinician about the most up-to-date techniques for the study of circulating leukocytes. The impact on cell phenotypes and on the function of leukocytes of extracorporeal and non-blood purification treatments proposed for sepsis were also analyzed. We conducted a systematic review using Pubmed/Medline, Ovid/Willey, the Cochrane Library, the Cochrane Controlled Trials Register, and EMBASE, combining key terms related to immunological function in sepsis and selected the most relevant clinical trials and review articles (excluding case reports) published in the last 50 years. The most important alteration in neutrophils during sepsis is that they activate an anti-apoptotic survival program. In septic monocytes, a reduced characteristic expression of HLA-DR is observed, but their role does not seem to be significantly altered in sepsis. As regards adaptive immunity, sepsis leads to lymphopenia and immunosuppression in patients with septic shock; this process involves all types of T cells (CD4, CD8 and Natural Killer), except for regulatory T cells, which retain their function. Several promising therapies that target the host immune response are currently under evaluation. During the worldwide pandemic caused by SARS-CoV-2, it was useful to study the “cytokine storm” to find additional treatments, such as the oXiris^® filter. This therapy can decrease the concentration of inflammatory markers that affect the severity of the disease.

Prevention and treatment of ventilator-associated pneumonia in COVID-19

Ventilator-associated pneumonia (VAP) is the most common acquired infection in the intensive care unit. Recent studies showed that the critical COVID-19 patients with invasive mechanical ventilation have a high risk of developing VAP, which result in a worse outcome and an increasing economic burden. With the development of critical care medicine, the morbidity and mortality of VAP remains high. Especially since the outbreak of COVID-19, the healthcare system is facing unprecedented challenges. Therefore, many efforts have been made in effective prevention, early diagnosis, and early treatment of VAP. This review focuses on the treatment and prevention drugs of VAP in COVID-19 patients. In general, prevention is more important than treatment for VAP. Prevention of VAP is based on minimizing exposure to mechanical ventilation and encouraging early release. There is little difference in drug prophylaxis from non-COVID-19. In term of treatment of VAP, empirical antibiotics is the main treatment, special attention should be paid to the antimicrobial spectrum and duration of antibiotics because of the existence of drug-resistant bacteria. Further studies with well-designed and large sample size were needed to demonstrate the prevention and treatment of ventilator-associated pneumonia in COVID-19 based on the specificity of COVID-19.