Probiotics for Preventing Ventilator-Associated Pneumonia in Mechanically Ventilated Patients: A Meta-Analysis with Trial Sequential Analysis

The effectiveness of probiotics as an adjunct therapy in patients under mechanical ventilation: an umbrella systematic review and meta-analysis

The literature regarding the role of probiotics in critically ill patients who have undergone mechanical ventilation (MV) is unclear; therefore, this umbrella systematic review and meta-analysis was carried out to clarify the effects of probiotics on the clinical outcomes of mechanically ventilated patients. The Scopus, PubMed/Medline, ISI Web of Science, and Google Scholar online databases were searched up to February 2023. All meta-analyses evaluating the impact of probiotics in patients under MV were considered eligible. The assessment of multiple systematic reviews (AMSTAR) questionnaire was used to evaluate the quality of the studies. Data were pooled using the random-effects approach. Thirty meta-analyses and nine clinical outcomes were re-analyzed. Probiotics significantly decreased ventilator-associated pneumonia (VAP) incidence, nosocomial infections, intensive care unit (ICU) length of stay, hospital length of stay, ICU mortality, hospital mortality, MV duration, duration of antibiotic use, and diarrhea. The obtained results of the current umbrella meta-analysis indicate that probiotic administration could be considered an adjunct therapy for critically ill patients; however, no specific probiotic treatment regimen can be recommended due to the diverse probiotics used in the included meta-analyses. The following microorganisms were used at various doses and combinations throughout the studies: Lacticaseibacillus casei, Lactiplantibacillus plantarum, L. acidophilus, L. delbrueckii, L. bulgaricus, Bifidobacterium longum, B. breve, B. salivarius, Pediococcus pentosaceus, Lactococcus raffinolactis, B. infantis, B. bifidum, Streptococcus thermophilus, Ligilactobacillus salivarius, L. lactis, B. lactis, Saccharomyces boulardii, L. rhamnosus GG, L. johnsonii, L. casei, S. faecalis, Clostridium butyricum, Bacillus mesentericus, L. sporogenes, S. boulardii, L. paracasei, B. subtilis, and Enterococcus faecium.

Prevention of ventilator-associated pneumonia with probiotics: an overview of systematic reviews

Background

Probiotics has been used as an adjuvant therapy for the prevention of ventilator-associated pneumonia (VAP). This study aimed to systematically compile, evaluate, and synthesize previous systematic reviews (SRs) and meta-analyses (MAs) on the prevention of VAP with probiotics.

Methods

The methodological quality, reporting quality, and evidence quality of enrolled studies were, respectively evaluated by Assessment of Multiple Systematic Reviews 2 (AMSTAR-2) tool, Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklists, and Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system.

Results

Thirteen eligible publications were analyzed in this overview. The included studies were rated as generally low methodological quality owing to the lack of a registered protocol or a list of exclusion criteria. The inadequate quality of the reports was demonstrated by the lack of reporting on the registration protocols, the lack of reporting on the search strategy, and the lack of reporting on the additional analyses. For GRADE, there were 36.17% (17/47) outcomes graded to be of moderate quality, 42.55% (20/47) to be of low quality, and 21.28% (10/47) to be of very low quality.

Conclusion

Probiotics may be associated with reduced incidence of VAP. However, caution should be exercised when recommending probiotics for the prevention of VAP owing to the poor quality of the current evidence.

Probiotics for Infection Prevention in Critically Ill and Trauma Patients: A Concise Review

BACKGROUND

Critically ill trauma patients are at an increased risk for infection, which can increase morbidity and mortality. The use of probiotic preparations for infection prevention is promising, yet the results of their effectiveness are mixed.

OBJECTIVES

To synthesize current research regarding the use of probiotics to prevent and possibly treat infection in the critically ill adult trauma population.

METHODS

RESULTS

CONCLUSION

Upon reviewing the current body of evidence, one cannot definitively conclude that probiotic supplementation in the critically-ill trauma population decreases health care-associated infection rates and improves outcomes, but most published evidence supports their use.

[Immunomodulation by nutritional intervention in critically ill patients]

Critically ill patients often suffer from a complex and severe immunological dysfunction. The differentiation and function of human immune cells are fundamentally controlled through metabolic processes. New concepts of immunonutrition therefore try to use enteral and parenteral nutrition to positively impact on the immune function of intensive care unit patients. This review article concisely presents the currently available evidence on the commonly used isolated supplements (anti-oxidative substances, amino acids, essential fatty acids) and difficulties related to their clinical use. The second part presents new and more comprehensive concepts of immunonutrition to influence the intestinal microbiome and to modulate the macronutrient composition. Immunonutrition of critically ill patients bears enormous potential and could become a valuable clinical tool for modulation of the immunometabolism of intensive care unit patients.

Optimization of Therapy and the Risk of Probiotic Use during Antibiotherapy in Septic Critically Ill Patients: A Narrative Review

Optimizing the entire therapeutic regimen in septic critically ill patients should be based not only on improving antibiotic use but also on optimizing the entire therapeutic regimen by considering possible drug–drug or drug–nutrient interactions. The aim of this narrative review is to provide a comprehensive overview on recent advances to optimize the therapeutic regimen in septic critically ill patients based on a pharmacokinetics and pharmacodynamic approach. Studies on recent advances on TDM-guided drug therapy optimization based on PK and/or PD results were included. Studies on patients <18 years old or with classical TDM-guided therapy were excluded. New approaches in TDM-guided therapy in septic critically ill patients based on PK and/or PD parameters are presented for cefiderocol, carbapenems, combinations beta-lactams/beta-lactamase inhibitors (piperacillin/tazobactam, ceftolozane/tazobactam, ceftazidime/avibactam), plazomicin, oxazolidinones and polymyxins. Increased midazolam toxicity in combination with fluconazole, nephrotoxic synergism between furosemide and aminoglycosides, life-threatening hypoglycemia after fluoroquinolone and insulin, prolonged muscle weakness and/or paralysis after neuromuscular blocking agents and high-dose corticosteroids combinations are of interest in critically ill patients. In the real-world practice, the use of probiotics with antibiotics is common; even data about the risk and benefits of probiotics are currently spares and inconclusive. According to current legislation, probiotic use does not require safety monitoring, but there are reports of endocarditis, meningitis, peritonitis, or pneumonia associated with probiotics in critically ill patients. In addition, probiotics are associated with risk of the spread of antimicrobial resistance. The TDM-guided method ensures a true optimization of antibiotic therapy, and particular efforts should be applied globally. In addition, multidrug and drug–nutrient interactions in critically ill patients may increase the likelihood of adverse events and risk of death; therefore, the PK and PD particularities of the critically ill patient require a multidisciplinary approach in which knowledge of clinical pharmacology is essential.

In critically ill patients, anti-anaerobic antibiotics increase risk of adverse clinical outcomes

BACKGROUND

Critically ill patients routinely receive antibiotics with activity against anaerobic gut bacteria. However, in other disease states and animal models, gut anaerobes are protective against pneumonia, organ failure and mortality. We therefore designed a translational series of analyses and experiments to determine the effects of anti-anaerobic antibiotics on the risk of adverse clinical outcomes among critically ill patients.

METHODS

We conducted a retrospective single-centre cohort study of 3032 critically ill patients, comparing patients who did and did not receive early anti-anaerobic antibiotics. We compared intensive care unit outcomes (ventilator-associated pneumonia (VAP)-free survival, infection-free survival and overall survival) in all patients and changes in gut microbiota in a subcohort of 116 patients. In murine models, we studied the effects of anaerobe depletion in infectious (Klebsiella pneumoniae and Staphylococcus aureus pneumonia) and noninfectious (hyperoxia) injury models.

RESULTS

Early administration of anti-anaerobic antibiotics was associated with decreased VAP-free survival (hazard ratio (HR) 1.24, 95% CI 1.06-1.45), infection-free survival (HR 1.22, 95% CI 1.09-1.38) and overall survival (HR 1.14, 95% CI 1.02-1.28). Patients who received anti-anaerobic antibiotics had decreased initial gut bacterial density (p=0.00038), increased microbiome expansion during hospitalisation (p=0.011) and domination by Enterobacteriaceae spp. (p=0.045). Enterobacteriaceae were also enriched among respiratory pathogens in anti-anaerobic-treated patients (p<2.2×10^-16). In murine models, treatment with anti-anaerobic antibiotics increased susceptibility to Enterobacteriaceae pneumonia (p<0.05) and increased the lethality of hyperoxia (p=0.0002).

CONCLUSIONS

In critically ill patients, early treatment with anti-anaerobic antibiotics is associated with increased mortality. Mechanisms may include enrichment of the gut with respiratory pathogens, but increased mortality is incompletely explained by infections alone. Given consistent clinical and experimental evidence of harm, the widespread use of anti-anaerobic antibiotics should be reconsidered.

Probiotics for preventing or treating COVID-19; a systematic review of research evidence and meta-analyses of efficacy for preventing death, severe disease, or disease progression

Background: COVID-19 variants threaten health globally. Despite improving vaccines and treatments, there is an urgent need for alternative strategies to prevent or reduce the severity of COVID-19. Potential strategies include probiotics, which are safe, inexpensive, globally available and have been studied previously in relation to respiratory infections. Methods: We performed a systematic review and meta-analyses of experimental, trial or observational research evidence evaluating probiotics compared with control groups for preventing or treating COVID-19. We searched PubMed, ProQuest, Google Scholar and Web of Science bibliographic databases for studies published until December 6, 2021. We then performed meta-analyses for outcomes reported consistently across studies. Outcomes reported inconsistently or not amenable to meta-analysis were compared descriptively. Results: We identified six eligible studies, which were all published in 2020 and 2021: one randomized controlled trial and five retrospective cohort studies. The only randomized controlled trial reported that groups that ingested probiotics compared with control groups that did not ingest probiotics did not differ significantly with respect to death, severe disease requiring admission to an intensive care unit or disease progression (all p>0.5). The five retrospective cohort studies reported various apparently beneficial and harmful COVID-19 outcome associations with probiotic ingestion. Meta-analyses revealed no significant associations between probiotic use and death, severe disease, or disease progression caused by COVID-19. Descriptive data revealed that probiotic ingestion was associated with a trend towards worsened duration of hospital stay, improvements in measures of respiratory condition and worsened disease duration. The evidence for these contradictory associations was weak because all studies were prone to bias and none were considered to be of high quality. Conclusions: Current evidence does not suggest that probiotics affect COVID-19 severity or mortality. However, additional higher quality studies need to be conducted to definitively determine if probiotics would be a useful adjunctive treatment for COVID-19.

The role of bacterial translocation in sepsis: a new target for therapy

Sepsis is a leading cause of death in critically ill patients, primarily due to multiple organ failures. It is associated with a systemic inflammatory response that plays a role in the pathogenesis of the disease. Intestinal barrier dysfunction and bacterial translocation (BT) play pivotal roles in the pathogenesis of sepsis and associated organ failure. In this review, we describe recent advances in understanding the mechanisms by which the gut microbiome and BT contribute to the pathogenesis of sepsis. We also discuss several potential treatment modalities that target the microbiome as therapeutic tools for patients with sepsis.

Probiotic in the prevention of ventilator-associated pneumonia in critically ill patients: evidence from meta-analysis and trial sequential analysis of randomized clinical trials

BACKGROUND

Probiotic might have a role in the prevention of ventilator-associated pneumonia (VAP) among mechanically ventilated patients, but the efficacy and safety remained inconsistent. The aim of this systematic review and meta-analysis was to evaluate the efficacy and safety of probiotic (prebiotic, synbiotic) versus placebo in preventing VAP in critically ill patients undergoing mechanical ventilation.

METHODS

PubMed, Embase and the Cochrane library databases were searched to 10 October 2021 without language restriction for randomized or semi-randomized controlled trials evaluating probiotic (prebiotic, synbiotic) vs. placebo in prevention of VAP in critically ill mechanically ventilated patients. The pooled relative risk (RR) along with 95% confidence intervals (CI) were combined using a random-effects model. Furthermore, the trial sequential analysis (TSA) and subgroup analyses were performed. Statistical significance was regarded as P < 0.05.

RESULTS

Twenty-three trials involving 5543 patients were eligible for this meta-analysis. The combined RR of decreasing the risk of VAP by probiotic was 0.67 (0.56, 0.81) for all eligible studies, 0.69 (n = 5136; 95% CI = 0.57 to 0.84; P < 0.01) for adults studies and 0.55 (n = 407; 95%CI = 0.31 to 0.99; P = 0.046) for neonates/children studies. Additionally, the above-mentioned positive finding in 20 adults studies was verified by the results of TSA, subgroup analyses and cumulative meta-analysis. Ample evidences demonstrated a 31% decrease in RR of incidence of VAP was noted when prophylactic probiotic therapy was administrated among adult patients. Finally, there were no effects on the ICU/hospital/28-/90-day mortality, bacteremia, CRBSI, diarrhea, ICU-acquired infections, infectious complications, pneumonia, UTI and wound infection between two groups (P > 0.05 for all).

CONCLUSIONS

Based on the results of our study, the current evidences suggested that prophylactic administration of probiotic might be utilized as a preventive method for VAP in neonates/children and adults patients who required mechanical ventilation. However, further large, high-quality RCTs are warranted to assess the efficacy and safety of probiotic treatment in critically ill patients, especially for the neonates/children studies and the long-term consequences of this therapy.

Current Status of Probiotics as Supplements in the Prevention and Treatment of Infectious Diseases

Probiotics play an important role against infectious pathogens via their effects on the epithelium, the production of antimicrobial compounds, and competitive exclusion. Administration of probiotic supplements may reduce the risk of infectious diseases and the use of antibiotics, hence contributing to a reduction or a delay of the development of multi-resistant bacteria. Infection is a constant concern for people who experience recurrent infections, and antibiotic treatment usually fails due to antibiotic resistance. Therefore, an infection can lead to severe illness and hospitalization if left untreated. A growing number of studies have demonstrated promising results for a variety of probiotic strains used to prevent or treat acute and recurrent infectious diseases, but additional standardized clinical research is needed.

Probiotics in Critically Ill Patients: An Umbrella Review

Objectives

Data sources

Study selection

Data extraction

Data synthesis

Conclusion

How to cite this article

Probiotics in the Intensive Care Unit

The understanding of the gut microbiome in health and disease has shown tremendous progress in the last decade. Shaped and balanced throughout life, the gut microbiome is intricately related to the local and systemic immune system and a multitude of mechanisms through which the gut microbiome contributes to the host’s defense against pathogens have been revealed. Similarly, a plethora of negative consequences, such as superinfections and an increased rate of hospital re-admissions, have been identified when the gut microbiome is disturbed by disease or by the iatrogenic effects of antibiotic treatment and other interventions. In this review, we describe the role that probiotics may play in the intensive care unit (ICU). We discuss what is known about the gut microbiome of the critically ill, and the concept of probiotic intervention to positively modulate the gut microbiome. We summarize the evidence derived from randomized clinical trials in this context, with a focus on the prevention of ventilator-associated pneumonia. Finally, we consider what lessons we can learn in terms of the current challenges, efficacy and safety of probiotics in the ICU and what we may expect from the future. Throughout the review, we highlight studies that have provided conceptual advances to the field or have revealed a specific mechanism; this narrative review is not intended as a comprehensive summary of the literature.

Clinical Benefits From Administering Probiotics to Mechanical Ventilated Patients in Intensive Care Unit: A PRISMA-Guided Meta-Analysis

Background

The use of probiotics has been considered as a new intervention for ventilator-associated pneumonia (VAP) prevention in the intensive care unit (ICU). The aim of this meta-analysis was to evaluate the effect of probiotics on mechanical-ventilated patients in ICU.

Methods

PubMed, Embase, Scopus, and the Cochrane Library were searched for relevant randomized controlled trials (RCTs) from their respective inception through October 10, 2021. All studies meeting the inclusion criteria were selected to evaluate the effect of probiotics on patients receiving mechanical ventilation in ICU.

Results

A total of 15 studies involving 4,693 participants met our inclusion criterion and were included in this meta-analysis. The incidence of VAP in the probiotic group was significantly lower (odds ratio [OR] 0.58, 95% CI 0.41 to 0.81; p = 0.002; I² = 71%). However, a publication bias may be present as the test of asymmetry was significant (p = 0.007). The probiotic administration was associated with a significant reduction in the duration of mechanical ventilation (mean difference [MD] −1.57, 95% CI −3.12 to −0.03; p = 0.05; inconsistency [I]² = 80%), length of ICU stay (MD −1.87, 95% CI −3.45 to −0.28; p = 0.02; I² = 76%), and incidence of bacterial colonization (OR 0.59, 95% CI 0.45 to 0.78; p = 0.0001; I² = 34%). Moreover, no statistically significant differences were observed regarding the incidence of diarrhea (OR 0.90, 95% CI 0.65 to 1.25; p = 0.54; I² = 12%) and mortality (OR 0.91, 95% CI 0.80 to 1.05; p = 0.19; I² = 0%) between probiotics group and control group.

Conclusion

Our meta-analysis shows that probiotics are associated with a reduction in VAP, as well as the duration of mechanical ventilation, ICU length of stay, and bacterial colonization, but no significant effects on ICU mortality and occurrence of diarrhea. However, in consideration of the significant heterogeneity and publication bias, our findings need to be further validated.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42020150770.

Enteral feeding and the microbiome in critically ill children: a narrative review

OBJECTIVE

This narrative review summarizes our current knowledge on the interplay between enteral nutrition (EN) and gut microbiota in critically ill children, using examples from two commonly encountered diagnoses in the pediatric intensive care unit (PICU): severe sepsis and acute respiratory distress syndrome (ARDS). This review will also highlight potential areas of therapeutic interventions that should be explored in future studies.

BACKGROUND

Critically ill children display extreme dysbiosis in their gut microbiome. Factors within the PICU that are often associated with dysbiosis include the use of broad-spectrum antibiotics, proton-pump inhibitors (PPIs), intravenous morphine, and fasting. Dysbiosis can potentially lead to adverse clinical outcomes (e.g., nosocomial infection, and prolonged hospitalization). EN may modulate dysbiosis. The gut microbiota is involved in the breaking down of macronutrients, mainly carbohydrates and proteins. Fermentation of undigestible carbohydrate (e.g., inulin and oligosaccharides), and amino acids by large intestine microbiota produces short chain fatty acids (SCFAs). SCFAs serve as the main fuel source for enterocytes and help to maintain healthy gut lining. Changes to selected components of macronutrients can result in alterations in gut microbiome and have potentially beneficial effects in patients in the PICU.

METHODS

A comprehensive search of the MEDLINE, Cochrane Library and Google Scholar databases was conducted using appropriate MESH terms and keywords. In this narrative review, we provide a summary of current knowledge on effect of EN on gut microbiota in pediatric studies, but also describes animal- and lab-based, as well as adult studies where relevant.

CONCLUSIONS

The gut microbiome can be altered by dietary modifications and common PICU practices and treatment. Although there are strong associations in restoring eubiosis and improvement in clinical outcomes, proving causality remains challenging. Further microbiome research is needed to provide mechanistic insights into the impact of the ever changing gut microbiome. In the future, new microbiota targeted therapies could potentially be the treatment of challenging PICU conditions and restore homeostasis in these children.

Mechanisms linking the human gut microbiome to prophylactic and treatment strategies for COVID-19

The recent COVID-19 pandemic has altered the face of biology, social interaction and public health worldwide. It has had a destructive effect upon millions of people and is approaching a devastating one million fatalities. Emerging evidence has suggested a link between the infection and gut microbiome status. This is one of the several factors that may contribute towards severity of infection. Given the fact that the gut is heavily linked to immunity, inflammatory status and the ability to challenge pathogens, it is worthwhile to consider dietary intervention of the gut microbiota as means of potentially challenging the viral outcome. In this context, probiotics and prebiotics have been used to mitigate similar respiratory infections. Here, we summarise links between the gut microbiome and COVID-19 infection, as well as propose mechanisms whereby probiotic and prebiotic interventions may act.

The microbiome and the immune system in critical illness

PURPOSE OF REVIEW

Although the gut microbiome plays a crucial role in the maintenance of health, it is hypothesized to drive morbidity and mortality in critically ill patients. This review describes the relationship between the gut microbiome and the immune system in critical illness.

RECENT FINDINGS

The gut microbiome is converted to a pathobiome in the ICU, characterized by decreased microbial diversity and pathogen predominance. These changes are induced by a pathologic microenvironment and are further exacerbated by common medical treatments initiated in the ICU. The conversion of the microbiome to a pathobiome has direct consequences on the regulation of inflammation and immunity by loss of beneficial host responses and initiation of maladaptive changes that can further propagate critical illness.

SUMMARY

The gut microbiome is dramatically altered in the ICU. In light of constant crosstalk between the microbiome and the host immune system, the pathobiome may play a key mechanistic role in driving a maladaptive response in critically ill patients. The pathobiome represents a potential therapeutic target in the management of critical illness whereby restoration of a healthier microbiome may directly alter the host inflammatory response, which could lead to improved patient outcomes.

The relevance of nutrition as a step forward to combat COVID-19

A new type of single-stranded RNA virus that belongs to the coronavirus’s family named SARS-CoV-2 has recently appeared, with fast-growing human to human transmissions. This virus has posed an important global health threat. Many nutrients can support the immune system and help in preventing or in ameliorating the response to viral infections. In the case of COVID-19, the unique pathophysiology of the coronavirus needs to be understood, in order to determine whether any potential nutrition intervention is indicated. A literature survey that comprised of ongoing research was conducted to evaluate the benefits of the bioactives present in food, such as: plant-derived extracts, vitamins, minerals, probiotics, and prebiotics, against the mechanisms of the COVID-19 infection. Although no food is yet confirmed to help in the prevention or in the treatment of the coronavirus transmission alone, exploring the possible implications of nutrition-infection interrelationships is of utmost importance. Well-designed and controlled clinical studies are emerging to explain whether the higher consumption of fruits, vegetables, protein-rich foods, unsaturated fatty acids, and other natural functional foods may aid in combating the COVID-19 infection. Meanwhile, a healthy and balanced diet is traditionally practised in viral infections that support the healthy gut microbiota profile. The human immune system function should be a vital prophylactic measure, along with adequate physical activities and sleeping habits. The consumption of immune-supportive nutrients is also encouraged in the elderly, comorbid, and in the immune-compromised as well as in malnourished individuals, in order to minimise the complications and the negative outcomes that are associated with the COVID-19 disease. Keywords: COVID-19 nutrition, mаcronutrients, micronutrients, bioactive compounds, malnutrition

Efficacy of Lactiplantibacillus plantarum 299 and 299v against nosocomial oropharyngeal pathogens in vitro and as an oral prophylactic treatment in a randomized, controlled clinical trial

Background

Disturbance in the oropharyngeal microbiota is common in hospitalized patients and contributes to the development of nosocomial pneumonia. Lactiplantibacillus plantarum 299 and 299v (Lp299 and Lp299v) are probiotic bacteria with beneficial effects on the human microbiome.

Aim

To investigate how Lp299 and Lp299v affect the growth of nosocomial oropharyngeal pathogens in vitro and to evaluate the efficacy in vivo when these probiotics are administered prophylactically in hospitalized patients.

Methods

The in vitro effect of Lp299 and Lp299v on nosocomial respiratory tract pathogens was evaluated using two methods, the co‐culture and agar overlay. In the clinical study, patients were randomized to orally receive either probiotics or placebo twice daily during their hospital stay. Oropharyngeal swabs were analyzed at inclusion and every fourth day throughout hospitalization.

Findings

All tested pathogens were completely inhibited by both Lp299 and Lp299v using the agar‐overlay method. In the co‐culture experiment, Lp299 and Lp299v significantly (p < 0.05) reduced the growth of all pathogens except for Enterococcus faecalis co‐incubated with Lp299. In the clinical study, daily oral treatment with Lp299 and Lp299v did not influence the development of disturbed oropharyngeal microbiota or nosocomial infection. Proton pump inhibitors, antibiotics, and steroid treatment were identified as risk factors for developing disturbed oropharyngeal microbiota.

Conclusions

Lp299 and Lp299v inhibited pathogen growth in vitro but did not affect the oropharyngeal microbiota in vivo. The ClinicalTrials.gov Identifier for this study is NCT02303301.

Efficacy of probiotics in the prevention of VAP in critically ill ICU patients: an updated systematic review and meta-analysis of randomized control trials

Introduction

Ventilator-associated pneumonia (VAP) is reported as the second most common nosocomial infection among critically ill patients with the incidence ranging from 2 to 16 episodes per 1000 ventilator days. The use of probiotics has been shown to have a promising effect in many RCTs. Our systematic review and meta-analysis were thus planned to determine the effect of probiotic use in critically ill ventilated adult patients on the incidence of VAP, length of hospital stay, length of ICU stay, duration of mechanical ventilation, the incidence of diarrhea, and the incidence of oropharyngeal colonization and in-hospital mortality.

Methodology

Systematic search of various databases (such as Embase, Cochrane, and Pubmed), published journals, clinical trials, and abstracts of the various major conferences were made to obtain the RCTs which compare probiotics with placebo for VAP prevention. The results were expressed as risk ratios or mean differences. Data synthesis was done using statistical software - Review Manager (RevMan) Version 5.4 (The Cochrane Collaboration, 2020).

Results

Nine studies met our inclusion criterion and were included in the meta-analysis. The incidence of VAP (risk ratio: 0.70, CI 0.56, 0.88; P = 0.002; I² = 37%), duration of mechanical ventilation (mean difference −3.75, CI −6.93, −0.58; P 0.02; I² = 96%), length of ICU stay (mean difference −4.20, CI −6.73, −1.66; P = 0.001; I² = 84%) and in-hospital mortality (OR 0.73, CI 0.54, 0.98; P = 0.04; I² = 0%) in the probiotic group was significantly lower than that in the control group. Probiotic administration was not associated with a statistically significant reduction in length of hospital stay (MD −1.94, CI −7.17, 3.28; P = 0.47; I² = 88%), incidence of oro-pharyngeal colonization (OR 0.59, CI 0.33, 1.04; P = 0.07; I² = 69%), and incidence of diarrhea (OR 0.59, CI 0.34, 1.03; P = 0.06; I² = 38%).

Discussion

Our meta-analysis shows that probiotic administration has a promising role in lowering the incidence of VAP, the duration of mechanical ventilation, length of ICU stay, and in-hospital mortality.

Reconsidering ventilator-associated pneumonia from a new dimension of the lung microbiome

Complex microbial communities that reside in the lungs, skin and gut are now appreciated for their role in maintaining organ, tissue and immune homoeostasis. As lungs are currently seen as an ecosystem, the shift in paradigm calls for the consideration of new algorithms related to lung ecology in pulmonology. Evidence of lung microbiota does not solely challenge the traditional physiopathology of ventilator-associated pneumonia (VAP); indeed, it also reinforces the need to include molecular techniques in VAP diagnosis and accelerate the use of immunomodulatory drugs, including corticosteroids, and other supplements such as probiotics for VAP prevention and/or treatment. With that stated, both microbiome and virome, including phageome, can lead to new opportunities in further understanding the relationship between health and dysbiosis in VAP. Previous knowledge may be, however, reconsidered at a microbiome scale.

Pathophysiology and protective approaches of gut injury in critical illness

The gut is a complex organ that has played an important role in digestion, absorption, endocrine functions, and immunity. The gut mucosal barriers consist of the immunologic barrier and nonimmunologic barrier. During critical illnesses, the gut is susceptible to injury due to the induction of intestinal hyperpermeability. Gut hyperpermeability and barrier dysfunction may lead to systemic inflammatory response syndrome. Additionally, gut microbiota are altered during critical illnesses. The etiology of such microbiome alterations in critical illnesses is multifactorial. The interaction or systemic host defense modulation between distant organs and the gut microbiome is increasingly studied in disease research. No treatment modality exists to significantly enhance the gut epithelial integrity, permeability, or mucus layer in critically ill patients. However, multiple helpful approaches including clinical and preclinical strategies exist. Enteral nutrition is associated with an increased mucosal barrier in animal and human studies. The trophic effects of enteral nutrition might help to maintain the intestinal physiology, prevent atrophy of gut villi, reduce intestinal permeability, and protect against ischemia-reperfusion injury. The microbiome approach such as the use of probiotics, fecal microbial transplantation, and selective decontamination of the digestive tract has been suggested. However, its evidence does not have a high quality. To promote rapid hypertrophy of the small bowel, various factors have been reported, including the epidermal growth factor, membrane permeant inhibitor of myosin light chain kinase, mucus surrogate, pharmacologic vagus nerve agonist, immune-enhancing diet, and glucagon-like peptide-2 as preclinical strategies. However, the evidence remains unclear.

The importance of airway and lung microbiome in the critically ill

During critical illness, there are a multitude of forces such as antibiotic use, mechanical ventilation, diet changes and inflammatory responses that could bring the microbiome out of balance. This so-called dysbiosis of the microbiome seems to be involved in immunological responses and may influence outcomes even in individuals who are not as vulnerable as a critically ill ICU population. It is therefore probable that dysbiosis of the microbiome is a consequence of critical illness and may, subsequently, shape an inadequate response to these circumstances.Bronchoscopic studies have revealed that the carina represents the densest site of bacterial DNA along healthy airways, with a tapering density with further bifurcations. This likely reflects the influence of micro-aspiration as the primary route of microbial immigration in healthy adults. Though bacterial DNA density grows extremely sparse at smaller airways, bacterial signal is still consistently detectable in bronchoalveolar lavage fluid, likely reflecting the fact that lavage via a wedged bronchoscope samples an enormous surface area of small airways and alveoli. The dogma of lung sterility also violated numerous observations that long predated culture-independent microbiology.The body's resident microbial consortia (gut and/or respiratory microbiota) affect normal host inflammatory and immune response mechanisms. Disruptions in these host-pathogen interactions have been associated with infection and altered innate immunity.In this narrative review, we will focus on the rationale and current evidence for a pathogenic role of the lung microbiome in the exacerbation of complications of critical illness, such as acute respiratory distress syndrome and ventilator-associated pneumonia.

The Gut Microbiota and Respiratory Diseases: New Evidence

Human body surfaces, such as the skin, intestines, and respiratory and urogenital tracts, are colonized by a large number of microorganisms, including bacteria, fungi, and viruses, with the gut being the most densely and extensively colonized organ. The microbiome plays an essential role in immune system development and tissue homeostasis. Gut microbiota dysbiosis not only modulates the immune responses of the gastrointestinal (GI) tract but also impacts the immunity of distal organs, such as the lung, further affecting lung health and respiratory diseases. Here, we review the recent evidence of the correlations and underlying mechanisms of the relationship between the gut microbiota and common respiratory diseases, including asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), lung cancer, and respiratory infection, and probiotic development as a therapeutic intervention for these diseases.

Pathogenesis-Targeted Preventive Strategies for Multidrug Resistant Ventilator-Associated Pneumonia: A Narrative Review

Ventilator-associated pneumonia (VAP) is the most common hospital-acquired infection in the intensive care unit (ICU), accounting for relevant morbidity and mortality among critically ill patients, especially when caused by multidrug resistant (MDR) organisms. The rising problem of MDR etiologies, which has led to a reduction in treatment options, have increased clinician’s attention to the employment of effective prevention strategies. In this narrative review we summarized the evidence resulting from 27 original articles that were identified through a systematic database search of the last 15 years, focusing on several pathogenesis-targeted strategies which could help preventing MDR-VAP. Oral hygiene with Chlorhexidine (CHX), CHX body washing, selective oral decontamination (SOD) and/or digestive decontamination (SDD), multiple decontamination regimens, probiotics, subglottic secretions drainage (SSD), special cuff material and shape, silver-coated endotracheal tubes (ETTs), universal use of gloves and contact isolation, alcohol-based hand gel, vaporized hydrogen peroxide, and bundles of care have been addressed. The most convincing evidence came from interventions directly addressed against the key factors of MDR-VAP pathogenesis, especially when they are jointly implemented into bundles. Further research, however, is warranted to identify the most effective combination.

Ventilator-associated pneumonia in adults: a narrative review

Ventilator-associated pneumonia (VAP) is one of the most frequent ICU-acquired infections. Reported incidences vary widely from 5 to 40% depending on the setting and diagnostic criteria. VAP is associated with prolonged duration of mechanical ventilation and ICU stay. The estimated attributable mortality of VAP is around 10%, with higher mortality rates in surgical ICU patients and in patients with mid-range severity scores at admission. Microbiological confirmation of infection is strongly encouraged. Which sampling method to use is still a matter of controversy. Emerging microbiological tools will likely modify our routine approach to diagnosing and treating VAP in the next future. Prevention of VAP is based on minimizing the exposure to mechanical ventilation and encouraging early liberation. Bundles that combine multiple prevention strategies may improve outcomes, but large randomized trials are needed to confirm this. Treatment should be limited to 7 days in the vast majority of the cases. Patients should be reassessed daily to confirm ongoing suspicion of disease, antibiotics should be narrowed as soon as antibiotic susceptibility results are available, and clinicians should consider stopping antibiotics if cultures are negative.

The microbiome and nutrition in critical illness

PURPOSE OF REVIEW

The present review aims to describe the relationship between nutrition and the gut microbiome in critical illness.

RECENT FINDINGS

Critical illness disrupts not only cells of human origin but also the intestinal microbiome, with a decrease in bacterial diversity and transformation into a pathobiome. Under basal conditions, nutrition profoundly alters microbial composition with significant salutatory effects on human health. In critical illness, enteral nutrition is recommended and has theoretical (but not proven) advantages towards improved inner microbial health and diminution of bacterial translocation. Dietary supplements such as probiotics and fiber have been shown to improve microbial derangements in health. However, their impact on the microbiome in critical illness is unclear and although they may have some beneficial effects on patient-centric outcomes, they do not alter mortality. The precise mechanisms of how nutrition and dietary supplements modulate the gut microbiome remain to be determined.

SUMMARY

Nutrition and supplements such as probiotics appear to play a significant role in modulating the microbiome in health, yet the relationship in critical illness is unclear. Further investigation is required to determine the mechanistic determinants of the impact of nutrition on the microbiome in critical illness and the potential clinical implications of this.

Antimicrobial-associated harm in critical care: a narrative review

The belief that, for the individual patient, the benefit of prompt and continued use of antimicrobials outweighs any potential harm is a significant barrier to improved stewardship of these vital agents. Antimicrobial stewardship may be perceived as utilitarian rationing, seeking to preserve the availability of effective antimicrobials by limiting the development of resistance in a manner which could conflict with the immediate treatment of the patient in need. This view does not account for the growing evidence of antimicrobial-associated harm to individual patients. This review sets out the evidence for antimicrobial-associated harm and how this should be balanced with the need for prompt and appropriate therapy in infection. It describes the mechanisms by which antimicrobials may harm patients including: mitochondrial toxicity; immune cell toxicity; adverse drug reactions; selection of resistant organisms within a given patient; and disruption of the microbiome. Finally, the article indicates how the harms of antimicrobials may be mitigated and identifies areas for research and development in this field.

The Importance of the Microbiome in Critically Ill Patients: Role of Nutrition

Critically ill patients have an alteration in the microbiome in which it becomes a disease-promoting pathobiome. It is characterized by lower bacterial diversity, loss of commensal phyla, like Firmicutes and Bacteroidetes, and a domination of pathogens belonging to the Proteobacteria phylum. Although these alterations are multicausal, many of the treatments administered to these patients, like antibiotics, play a significant role. Critically ill patients also have a hyperpermeable gut barrier and dysregulation of the inflammatory response that favor the development of the pathobiome, translocation of pathogens, and facilitate the emergence of sepsis. In order to restore the homeostasis of the microbiome, several nutritional strategies have been evaluated with the aim to improve the management of critically ill patients. Importantly, enteral nutrition has proven to be more efficient in promoting the homeostasis of the gut microbiome compared to parenteral nutrition. Several nutritional therapies, including prebiotics, probiotics, synbiotics, and fecal microbiota transplantation, are currently being used, showing variable results, possibly due to the unevenness of clinical trial conditions and the fact that the beneficial effects of probiotics are specific to particular species or even strains. Thus, it is of great importance to better understand the mechanisms by which nutrition and supplement therapies can heal the microbiome in critically ill patients in order to finally implement them in clinical practice with optimal safety and efficacy.

Synbiotics for prevention of ventilator-associated pneumonia: a probiotics strain-specific network meta-analysis

Objective

Probiotics may be efficacious in preventing ventilator-associated pneumonia (VAP). The aim of this network meta-analysis (NMA) was to clarify the efficacy of different types of probiotics for preventing VAP.

Methods

This systematic review and NMA was conducted according to the updated preferred reporting items for systematic review and meta-analysis. A systematic literature search of public databases from inception to 17 June 2018 was performed.

Results

NMA showed that “Bifidobacterium longum + Lactobacillus bulgaricus + Streptococcus thermophiles” was more efficacious than “Ergyphilus” in preventing VAP (odds ratio: 0.15, 95% confidence interval: 0.03–0.94). According to pairwise meta-analysis, “B. longum + L. bulgaricus + S. thermophiles” and “Lactobacillus rhamnosus” were superior to placebo in preventing VAP. Treatment rank based on surface under the cumulative ranking curves revealed that the most efficacious treatment for preventing VAP was “B. longum + L. bulgaricus + S. thermophiles” (66%). In terms of reducing hospital mortality and ICU mortality, the most efficacious treatment was Synbiotic 2000FORTE (34% and 46%, respectively).

Conclusions

Based on efficacy ranking, “B. longum + L. bulgaricus + S. thermophiles” should be the first choice for prevention of VAP, while Synbiotic 2000FORTE has the potential to reduce in-hospital mortality and ICU mortality.

The gut microbiome alters immunophenotype and survival from sepsis

The microbiome is increasingly implicated in immune regulation and mortality from sepsis. Mice with identical genetic backgrounds but distinct microbiomes were obtained from different vendors and analyzed following cecal ligation and puncture (CLP). β diversity of the microbiome measured from feces demonstrated significant differences between The Jackson Laboratory (Jax; Bar Harbor, ME, USA) and Charles River Laboratories (CR; Wilmington, MA, USA) C57/B6 mice. Jax mice had 7-d mortality of 90% following CLP, whereas CR mice had a mortality of 53%. Differences in vendor were associated with altered immunophenotype with increased splenic IFN-γ⁺CD4⁺ T cells, effector memory CD4⁺ T cells, and central memory CD4⁺ T cells and increased Peyer's patch effector memory CD4⁺ T cells in septic CR mice. To determine whether differences in the microbiome were responsible for these differences, Jax and CR mice were cohoused for 3 wk, after which they assumed a similar microbiota composition. Cohoused mice had improved survival following CLP compared to Jax mice and had similar survival regardless of their vendor of origin. All differences in immunophenotype between septic Jax and CR mice disappeared following cohousing. These findings suggest that the microbiome plays a crucial role in survival and the host immune response from sepsis and represents a potential target for therapeutic intervention.-Fay, K. T., Klingensmith, N. J., Chen, C.-W., Zhang, W., Sun, Y., Morrow, K. N., Liang, Z., Burd, E. M., Ford, M. L., Coopersmith, C. M. The gut microbiome alters immunophenotype and survival from sepsis.

Clinical Nutrition in Critical Care Medicine - Guideline of the German Society for Nutritional Medicine (DGEM)

PURPOSE

Enteral and parenteral nutrition of adult critically ill patients varies in terms of the route of nutrient delivery, the amount and composition of macro- and micronutrients, and the choice of specific, immune-modulating substrates. Variations of clinical nutrition may affect clinical outcomes. The present guideline provides clinicians with updated consensus-based recommendations for clinical nutrition in adult critically ill patients who suffer from at least one acute organ dysfunction requiring specific drug therapy and/or a mechanical support device (e.g., mechanical ventilation) to maintain organ function.

METHODS

The former guidelines of the German Society for Nutritional Medicine (DGEM) were updated according to the current instructions of the Association of the Scientific Medical Societies in Germany (AWMF) valid for a S2k-guideline. According to the S2k-guideline classification, no systematic review of the available evidence was required to make recommendations, which, therefore, do not state evidence- or recommendation grades. Nevertheless, we considered and commented the evidence from randomized-controlled trials, meta-analyses and observational studies with adequate sample size and high methodological quality (until May 2018) as well as from currently valid guidelines of other societies. The liability of each recommendation was described linguistically. Each recommendation was finally validated and consented through a Delphi process.

RESULTS

In the introduction the guideline describes a) the pathophysiological consequences of critical illness possibly affecting metabolism and nutrition of critically ill patients, b) potential definitions for different disease phases during the course of illness, and c) methodological shortcomings of clinical trials on nutrition. Then, we make 69 consented recommendations for essential, practice-relevant elements of clinical nutrition in critically ill patients. Among others, recommendations include the assessment of nutrition status, the indication for clinical nutrition, the timing and route of nutrient delivery, and the amount and composition of substrates (macro- and micronutrients); furthermore, we discuss distinctive aspects of nutrition therapy in obese critically ill patients and those treated with extracorporeal support devices.

CONCLUSION

The current guideline provides clinicians with up-to-date recommendations for enteral and parenteral nutrition of adult critically ill patients who suffer from at least one acute organ dysfunction requiring specific drug therapy and/or a mechanical support device (e.g., mechanical ventilation) to maintain organ function. The period of validity of the guideline is approximately fixed at five years (2018-2023).

Evaluating probiotics for the prevention of ventilator-associated pneumonia: a randomised placebo-controlled multicentre trial protocol and statistical analysis plan for PROSPECT

INTRODUCTION

Ventilator-associated pneumonia (VAP) is the most common healthcare-associated infection in critically ill patients. Prior studies suggest that probiotics may reduce VAP and other infections in critically ill patients; however, most previous randomised trials were small, single centre studies. The Probiotics: Prevention of Severe Pneumonia and Endotracheal Colonization Trial (PROSPECT) aims to determine the impact of the probiotic Lactobacillus rhamnosus GG on VAP and other clinically important outcomes in critically ill adults.

METHODS

PROSPECT is a multicentre, concealed, randomised, stratified, blinded, controlled trial in patients ≥18 years old, anticipated to be mechanically ventilated ≥72 hours, in intensive care units (ICUs) in Canada, the USA and Saudi Arabia. Patients receive either 1×10¹⁰ colony forming units of L. rhamnosus GG twice daily or an identical appearing placebo. Those at increased risk of probiotic infection are excluded. The primary outcome is VAP. Secondary outcomes are other ICU-acquired infections including Clostridioides difficile infection, diarrhoea (including antibiotic-associated diarrhoea), antimicrobial use, ICU and hospital length of stay and mortality. The planned sample size of 2650 patients is based on an estimated 15% VAP rate and will provide 80% power to detect a 25% relative risk reduction.

ETHICS AND DISSEMINATION

This protocol and statistical analysis plan outlines the methodology, primary and secondary analyses, sensitivity analyses and subgroup analyses. PROSPECT is approved by Health Canada (#9427-M1133-45C), the research ethics boards of all participating hospitals and Public Health Ontario. Results will be disseminated via academic channels (peer reviewed journal publications, professional healthcare fora including international conferences) and conventional and social media. The results of PROSPECT will inform practice guidelines worldwide.

TRIALREGISTRATION NUMBER

NCT02462590; Pre-results.

Gut integrity in critical illness

Background

The gut is hypothesized to be the “motor” of critical illness. Under basal conditions, the gut plays a crucial role in the maintenance of health. However, in critical illness, all elements of the gut are injured, potentially worsening multiple organ dysfunction syndrome.

Main body

Under basal conditions, the intestinal epithelium absorbs nutrients and plays a critical role as the first-line protection against pathogenic microbes and as the central coordinator of mucosal immunity. In contrast, each element of the gut is impacted in critical illness. In the epithelium, apoptosis increases, proliferation decreases, and migration slows. In addition, gut barrier function is worsened via alterations to the tight junction, resulting in intestinal hyperpermeability. This is associated with damage to the mucus that separates the contents of the intestinal lumen from the epithelium. Finally, the microbiome of the intestine is converted into a pathobiome, with an increase in disease-promoting bacteria and induction of virulence factors in commensal bacteria. Toxic factors can then leave the intestine via both portal blood flow and mesenteric lymph to cause distant organ damage.

Conclusion

The gut plays a complex role in both health and critical illness. Here, we review gut integrity in both health and illness and highlight potential strategies for targeting the intestine for therapeutic gain in the intensive care unit.

Critical illness and the role of the microbiome

The number of microbes living within the intestinal lumen is similar to the number of all cells of human origin in the host. Although historically little attention has been paid to the massive microbial community residing inside each of us, the last few years have witnessed an explosion of information related to the role of the microbiome in the maintenance of health and in the pathogenesis of disease. Here, we review data suggesting that the microbiome is converted into a pathobiome in critical illness and potential strategies for targeting the microbiome for therapeutic gain in the intensive care unit.

Relationship between Ventilator-Associated Events and Timing of Rehabilitation in Subjects with Emergency Tracheal Intubation at Early Mobilization Facility

The present study aimed to investigate the relationship between the occurrence of ventilator-associated events (VAE) in the intensive care unit and the timing of rehabilitation intervention. We included subjects who underwent emergency tracheal intubation and received rehabilitation. We performed rehabilitation according to our hospital’s protocol. We assessed the mechanical ventilation parameters of inspired oxygen fraction and positive-end expiratory pressure, and a VAE was identified if these parameters stabilized or decreased for ≥2 days and then had to be increased for ≥2 days. We defined time in hours from tracheal intubation to the first rehabilitation intervention as Timing 1 and that to first sitting on the edge of the bed as Timing 2. Data were analyzed by the t-test and χ² tests. We finally analyzed 294 subjects. VAE occurred in 9.9% and high mortality at 48.3%. Median values of Timing 1 and Timing 2 in the non-VAE and VAE groups were 30.3 ± 24.0 and 30.0 ± 20.7 h, and 125.7 ± 136.6 and 127.9 ± 111.4 h, respectively, and the differences were not significant (p = 0.95 and p = 0.93, respectively). We found no significant relationship between the occurrence of VAE leading to high mortality and timing of rehabilitation intervention.