Probiotics in the critically ill: a systematic review of the randomized trial evidence

Beyond Conventional Drug Design: Exploring the Broad-Spectrum Efficacy of Antimicrobial Peptides

In the fight against pathogenic infections, antimicrobial peptides (AMPs) constitute a novel and promising class of compounds that defies accepted drug development conventions like Lipinski's rule. AMPs are remarkably effective against a variety of pathogens, including viruses, bacteria, parasites, and fungi. Their effectiveness, despite differing from traditional drug-like properties defies accepted standards. This review investigates the complex world of AMPs with an emphasis on their structural and physicochemical properties, which include size, sequence, structure, charge, and half-life. These distinguishing characteristics set AMPs apart from conventional therapeutics that adhere to Lipinski's rules and greatly contribute to their selective targeting, reduction of resistance, multifunctionality, and broad-spectrum efficacy. In contrast to traditional drugs that follow Lipinski's guidelines, AMPs have special qualities that play a big role in their ability to target specific targets, lower resistance, and work across a wide range of conditions. Our work is unique because of this nuanced investigation, which offers a new viewpoint on the potential of AMPs in tackling the worldwide problem of antibiotic resistance. In the face of the escalating global challenge of antibiotic resistance, antimicrobial peptides (AMPs) are innovative antimicrobial agents with unique mechanisms of action that challenge traditional Lipinski's Rule. They can withstand various microbial threats through membrane disruption, intracellular targeting, and immunomodulation. AMP versatility sets them apart from other antibiotics and their potential to address microbial infections and antibiotic resistance is growing. To fully unlock their potential, traditional drug development approaches need to be reconsidered. AMPs have revolutionary potential, paving the way for innovative solutions to health issues and transforming the antimicrobial therapy landscape.

Probiotic-based therapy as a new useful strategy for the treatment of patients with traumatic brain injury

BACKGROUND

In the new era, microbial-based medicine is one of the best strategies that try to modify the normal flora with the aim of treating some disorders. This systematic review and meta-analysis was performed to evaluate the use of probiotics in the treatment of the clinical outcomes in cases with traumatic brain injury..

METHODS

In this regard, the search strategy was done using databases such as PubMed, Embase, Scopus, CENTRAL, and Google Scholar, from 2006 until April 2024. All studies about the efficacy of probiotic supplementation on the clinical outcomes in traumatic brain injury patients were retrieved. During the assessment process of the eligible studies, we evaluated clinical characteristics such as the Glasgow Coma Scale score, the Sequential Organ Failure Assessment score, the Acute Physiology and Chronic Health Evaluation II score, referral rate and hospitalization period in the intensive care unit, mortality rate, as well as opportunistic infections in both groups of case and control..

RESULTS

In this study, the authors analyzed data from 6 articles including 391 cases with traumatic brain injury. Our results showed that the probiotic therapy increases the Glasgow Coma Scale score in patients with the average age of more than 50 years. However, there was no a significant difference in the Sequential Organ Failure Assessment and the Acute Physiology and Chronic Health Evaluation scores between the group that had received probiotics and the control group. Although probiotic-based treatment did not significantly affect the intensive care unit admission (or length of stay), but, the risk of infection, and also mortality was significantly lower in the probiotic group (OR: 0.53; 95% CI: 0.3 to 0.8, as well as OR: 0.41; 95% CI: 0.2 to 0.7, respectively)..

CONCLUSIONS

Overall, due to the modification of microbial flora, probiotic supplements can balance microflora disturbances, which in turn leads to improvement the clinical outcomes in patients with brain injury. Therefore, probiotic-based therapy can be considered as a promising strategy for the treatment of the central nervous system disorders. However, given the limited evidence, more clinical trial studies need to strengthen our results..

Benefits and harm of probiotics and synbiotics in adult critically ill patients. A systematic review and meta-analysis of randomized controlled trials with trial sequential analysis

BACKGROUND & AIMS

Several systematic reviews and meta-analyses of randomized controlled trials concluded that probiotics administration in critically ill patients was safe and associated with reduced rates of ventilator-associated pneumonia and diarrhea. However, a recent large multicenter trial found probiotics administration, compared to placebo, was not efficacious and increased adverse events. An updated meta-analysis that controls for type-1 and -2 errors using trial sequential analysis, with a detailed account of adverse events associated with probiotic administration, is warranted to confirm the safety and efficacy of probiotic use in critically ill patients.

METHODS

RCTs that compared probiotics or synbiotics to usual care or placebo and reported clinical and diarrheal outcomes were searched in 4 electronic databases from inception to March 8, 2022 without language restriction. Four reviewers independently extracted data and assessed the study qualities using the Critical Care Nutrition (CCN) Methodological Quality Scoring System. Random-effect meta-analysis and trial sequential analysis (TSA) were used to synthesize the results. The primary outcome was ventilator-associated pneumonia (VAP). The main subgroup analysis compared the effects of higher versus lower quality studies (based on median CCN score).

RESULTS

Seventy-five studies with 71 unique trials (n = 8551) were included. In the overall analysis, probiotics significantly reduced VAP incidence (risk ratio [RR] 0.70, 95% confidence interval [CI] 0.56-0.88; I² = 65%; 16 studies). However, such benefits were demonstrated only in lower (RR 0.47, 95% CI 0.32, 0.69; I² = 44%; 7 studies) but not higher quality studies (RR 0.89, 95% CI 0.73, 1.08; I² = 43%; 9 studies), with significant test for subgroup differences (p = 0.004). Additionally, TSA showed that the VAP benefits of probiotics in the overall and subgroup analyses were type-1 errors. In higher quality trials, TSA found that future trials are unlikely to demonstrate any benefits of probiotics on infectious complications and diarrhea. Probiotics had higher adverse events than control (pooled risk difference: 0.01, 95% CI 0.01, 0.02; I² = 0%; 22 studies).

CONCLUSION

High-quality RCTs did not support a beneficial effect of probiotics on clinical or diarrheal outcomes in critically ill patients. Given the lack of benefits and the increased incidence of adverse events, probiotics should not be routinely administered to critically ill patients.

PROSPERO REGISTRATION

CRD42022302278.

Effects of Probiotics Supplementation on CRP, IL-6, and Length of ICU Stay in Traumatic Brain Injuries and Multiple Trauma Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

METHOD

This meta-analysis aims to evaluate the effectiveness of probiotics in reducing inflammatory biomarkers and the length of intensive care unit (ICU) stays. PubMed-Medline, SCOPUS, Embase, and Google Scholar databases up to July 2021 were searched. The meta-analysis was carried out using random-effect analysis. To determine the sources of heterogeneity, subgroup analyses were performed. In case of the presence of publication bias, trim and fill analysis was carried out. The Cochrane Collaboration tool was used for checking the quality assessment. We hypothesized that probiotics would improve inflammatory markers (CRP and IL-6) and the length of ICU stay in traumatic brain injury and multiple trauma patients.

RESULTS

The present meta-analysis, which includes a total of seven studies, showed that there were no significant effects of probiotics supplementation on interleukin (IL)-6 (Hedges's g = -2.46 pg/ml; 95% CI: -12.16, 7.25; P=0.39), C-reactive protein (CRP) (Hedges's g = -1.10 mg/L; 95% CI: -2.27, 0.06; P=0.06), and the length of staying in ICU. The overall number of RCTs included in the analysis and the total sample size were insufficient to make firm conclusions.

CONCLUSION

As a result, more carefully designed RCTs are needed to investigate the effect of probiotics on inflammatory biomarkers and the length of ICU stay in traumatic brain injuries and multiple trauma patients in greater detail.

Probiotic Supplementation Prevents the Development of Ventilator-Associated Pneumonia for Mechanically Ventilated ICU Patients: A Systematic Review and Network Meta-analysis of Randomized Controlled Trials

Background

Ventilator-associated pneumonia (VAP) is one of the common critical complications of nosocomial infection (NI) in invasive mechanically ventilated intensive care unit (ICU) patients. The efficacy of total parenteral nutrition (TPN), enteral nutrition and/or adjuvant peripheral parenteral nutrition (EPN) supplemented with or without probiotic, prebiotic, and synbiotic therapies in preventing VAP among these patients has been questioned. We aimed to systematically and comprehensively summarize all available studies to generate the best evidence of VAP prevention for invasive mechanically ventilated ICU patients.

Methods

Randomized controlled trials (RCTs) for the administration of TPN, EPN, probiotics-supplemented EPN, prebiotics-supplemented EPN, and synbiotics-supplemented EPN for VAP prevention in invasive mechanically ventilated ICU patients were systematically retrieved from four electronic databases. The incidence of VAP was the primary outcome and was determined by the random-effects model of a Bayesian framework. The secondary outcomes were NI, ICU and hospital mortality, ICU and hospital length of stay, and mechanical ventilation duration. The registration number of Prospero is CRD42020195773.

Results

A total of 8339 patients from 31 RCTs were finally included in network meta-analysis. The primary outcome showed that probiotic-supplemented EPN had a higher correlation with the alleviation of VAP than EPN in critically invasive mechanically ventilated patients (odds ratio [OR] 0.75; 95% credible intervals [CrI] 0.58–0.95). Subgroup analyses showed that probiotic-supplemented EPN prevented VAP in trauma patients (OR 0.30; 95% CrI 0.13–0.83), mixed probiotic strain therapy was more effective in preventing VAP than EPN therapy (OR 0.55; 95% CrI 0.31–0.97), and low-dose probiotic therapy (less than 10¹⁰ CFU per day) was more associated with lowered incidence of VAP than EPN therapy (OR 0.16; 95% CrI 0.04–0.64). Secondary outcomes indicated that synbiotic-supplemented EPN therapy was more significantly related to decreased incidence of NI than EPN therapy (OR 0.34; 95% CrI 0.11–0.85). Prebiotic-supplemented EPN administration was the most effective in preventing diarrhea (OR 0.05; 95% CrI 0.00–0.71).

Conclusion

Probiotic supplementation shows promise in reducing the incidence of VAP in critically invasive mechanically ventilated patients. Currently, low quality of evidence reduces strong clinical recommendations. Further high-quality RCTs are needed to conclusively prove these findings.

Systamatic Review Registration

[https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020195773], identifier [CRD42020195773].

Strategies to prevent ventilator-associated pneumonia, ventilator-associated events, and nonventilator hospital-acquired pneumonia in acute-care hospitals: 2022 Update

The purpose of this document is to highlight practical recommendations to assist acute care hospitals to prioritize and implement strategies to prevent ventilator-associated pneumonia (VAP), ventilator-associated events (VAE), and non-ventilator hospital-acquired pneumonia (NV-HAP) in adults, children, and neonates. This document updates the Strategies to Prevent Ventilator-Associated Pneumonia in Acute Care Hospitals published in 2014. This expert guidance document is sponsored by the Society for Healthcare Epidemiology (SHEA), and is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America, the American Hospital Association, the Association for Professionals in Infection Control and Epidemiology, and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise.

Probiotics in Critically Ill Patients: An Umbrella Review

Objectives

Data sources

Study selection

Data extraction

Data synthesis

Conclusion

How to cite this article

The role of the microbiota in the management of intensive care patients

The composition of the gut microbiota is highly dynamic and changes according to various conditions. The gut microbiota mainly includes difficult-to-cultivate anaerobic bacteria, hence knowledge about its composition has significantly arisen from culture-independent methods based on next-generation sequencing (NGS) such as 16S profiling and shotgun metagenomics. The gut microbiota of patients hospitalized in intensive care units (ICU) undergoes many alterations because of critical illness, antibiotics, and other ICU-specific medications. It is then characterized by lower richness and diversity, and dominated by opportunistic pathogens such as Clostridioides difficile and multidrug-resistant bacteria. These alterations are associated with an increased risk of infectious complications or death. Specifically, at the time of writing, it appears possible to identify distinct microbiota patterns associated with severity or infectivity in COVID-19 patients, paving the way for the potential use of dysbiosis markers to predict patient outcomes. Correcting the microbiota disturbances to avoid their consequences is now possible. Fecal microbiota transplantation is recommended in recurrent C. difficile infections and microbiota-protecting treatments such as antibiotic inactivators are currently being developed. The growing interest in the microbiota and microbiota-associated therapies suggests that the control of the dysbiosis could be a key factor in the management of critically ill patients. The present narrative review aims to provide a synthetic overview of microbiota, from healthy individuals to critically ill patients. After an introduction to the different techniques used for studying the microbiota, we review the determinants involved in the alteration of the microbiota in ICU patients and the latter's consequences. Last, we assess the means to prevent or correct microbiota alteration.

Effect of Probiotics on Incident Ventilator-Associated Pneumonia in Critically Ill Patients: A Randomized Clinical Trial

IMPORTANCE

Growing interest in microbial dysbiosis during critical illness has raised questions about the therapeutic potential of microbiome modification with probiotics. Prior randomized trials in this population suggest that probiotics reduce infection, particularly ventilator-associated pneumonia (VAP), although probiotic-associated infections have also been reported.

OBJECTIVE

To evaluate the effect of Lactobacillus rhamnosus GG on preventing VAP, additional infections, and other clinically important outcomes in the intensive care unit (ICU).

DESIGN, SETTING, AND PARTICIPANTS

Randomized placebo-controlled trial in 44 ICUs in Canada, the United States, and Saudi Arabia enrolling adults predicted to require mechanical ventilation for at least 72 hours. A total of 2653 patients were enrolled from October 2013 to March 2019 (final follow-up, October 2020).

INTERVENTIONS

Enteral L rhamnosus GG (1 × 1010 colony-forming units) (n = 1321) or placebo (n = 1332) twice daily in the ICU.

MAIN OUTCOMES AND MEASURES

The primary outcome was VAP determined by duplicate blinded central adjudication. Secondary outcomes were other ICU-acquired infections including Clostridioides difficile infection, diarrhea, antimicrobial use, ICU and hospital length of stay, and mortality.

RESULTS

Among 2653 randomized patients (mean age, 59.8 years [SD], 16.5 years), 2650 (99.9%) completed the trial (mean age, 59.8 years [SD], 16.5 years; 1063 women [40.1%.] with a mean Acute Physiology and Chronic Health Evaluation II score of 22.0 (SD, 7.8) and received the study product for a median of 9 days (IQR, 5-15 days). VAP developed among 289 of 1318 patients (21.9%) receiving probiotics vs 284 of 1332 controls (21.3%; hazard ratio [HR], 1.03 (95% CI, 0.87-1.22; P = .73, absolute difference, 0.6%, 95% CI, -2.5% to 3.7%). None of the 20 prespecified secondary outcomes, including other ICU-acquired infections, diarrhea, antimicrobial use, mortality, or length of stay showed a significant difference. Fifteen patients (1.1%) receiving probiotics vs 1 (0.1%) in the control group experienced the adverse event of L rhamnosus in a sterile site or the sole or predominant organism in a nonsterile site (odds ratio, 14.02; 95% CI, 1.79-109.58; P < .001).

CONCLUSIONS AND RELEVANCE

Among critically ill patients requiring mechanical ventilation, administration of the probiotic L rhamnosus GG compared with placebo, resulted in no significant difference in the development of ventilator-associated pneumonia. These findings do not support the use of L rhamnosus GG in critically ill patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02462590.

Microbiome in Critical illness: An Unconventional and Unknown Ally

BACKGROUND

The digestive tract represents an interface between the external environment and the body where the interaction of a complex polymicrobial ecology has an important influence on health and disease. The physiological mechanisms that are altered during the hospitalization and in the intensive care unit (ICU) contribute to the pathobiota's growth. Intestinal dysbiosis occurs within hours of being admitted to ICU. This may be due to different factors, such as alterations of normal intestinal transit, administration of variuos medications or alterations in the intestinal wall which causes a cascade of events that will lead to the increase of nitrates and decrease of oxygen concentration, liberation of free radicals.

OBJECTIVE

This work aims to report the latest updates on the microbiota's contribution to developing sepsis in patients in the ICU department. In this short review were reviewed the latest scientific findings on the mechanisms of intestinal immune defenses performed both locally and systemically. In addition, we considered it necessary to review the literature to report the current best treatment strategies to prevent the infection spread which can bring systemic infections in patients admitted to ICU.

MATERIAL AND METHODS

This review has been written to answer at three main questions: what are the main intestinal flora's defense mechanisms that help us to prevent the risk of developing systemic diseases on a day-to-day basis? What are the main dysbiosis' systemic abnormalities? What are the modern strategies that are used in the ICU patients to prevent the infection spread? Using the combination of following keywords: microbiota and ICU, ICU and gut, microbiota and critical illness, microbiota and critical care, microbiota and sepsis, microbiota and infection, gastrointestinal immunity,in the Cochrane Controlled Trials Register, the Cochrane Library, medline and pubmed, google scholar, ovid/wiley. Finally, we reviewed and selected 72 articles. We also consulted the site ClinicalTrials.com to find out studies that are recently conducted or ongoing.

RESULTS

The critical illness can alter intestinal bacterial flora leading to homeostasis disequilibrium. Despite numerous mechanisms, such as epithelial cells with calciform cells that together build a mechanical barrier for pathogenic bacteria, the presence of mucous associated lymphoid tissue (MALT) which stimulates an immune response through the production of interferon-gamma (IFN-y) and THN-a or by stimulating lymphocytes T helper-2 produces anti-inflammatory cytokines. But these defenses can be altered following a hospitalization in ICU and lead to serious complications such as acute respiratory distress syndrome (ARDS), health care associated pneumonia (HAP) and ventilator associated pneumonia (VAP), Systemic infection and multiple organ failure (MOF), but also in the development of coronary artery disease (CAD). In addition, the microbiota has a significant impact on the development of intestinal complications and the severity of the SARS-COVID-19 patients.

CONCLUSION

The microbiota is recognized as one of the important factors that can worsen the clinical conditions of patients who are already very frailty in intensive care unit. At the same time, the microbiota also plays a crucial role in the prevention of ICU associated complications. By using the resources, we have available, such as probiotics, symbiotics or fecal microbiota transplantation (FMT), we can preserve the integrity of the microbiota and the GUT, which will later help maintain homeostasis in ICU patients.

Effects of Probiotics in Conditions or Infections Similar to COVID-19 on Health Outcomes: An Evidence Analysis Center Scoping Review

Probiotics have been suggested as a potential intervention for improving outcomes, particularly ventilatory-associated pneumonia, in patients infected with coronavirus disease 2019 (COVID-19). However, with the rapid development of the COVID-19 pandemic, there is little direct evidence available in infected patients. The objective of this scoping review is to examine the availability and nature of literature describing the effect of probiotics in adults with conditions or infections similar to COVID-19 infection on related health outcomes. MEDLINE, Cumulative Index to Nursing & Allied Health Literature, and Cochrane Databases were searched for studies published from 1999 to May 1, 2020, examining the effect of probiotics in conditions applicable to individuals infected with COVID-19, including, but not limited to, other forms of coronavirus, critical illness, and mechanical ventilation. The databases search identified 1925 unique articles, 77 full-text articles were reviewed, and 48 studies were included in this scoping review, including 31 primary studies and 17 systematic reviews. Primary studies examined a range of interventions that varied by probiotic diversity and types, including 8 studies that focused on synbiotics, which include both pre- and probiotics. Several systematic reviews examined the effect of probiotics on ventilator-associated pneumonia and other infections. Although most systematic reviews concluded probiotics may improve these outcomes, most systematic review authors concluded that the evidence was low in quality and high in heterogeneity. In the absence of direct evidence with patients infected with COVID-19, studies in comparable populations are currently the best resource to guide probiotics interventions in conjunction with clinical expertise and multidisciplinary health care planning.

Probiotic Bacterial Application in Pediatric Critical Illness as Coadjuvants of Therapy

The use of probiotics in critically ill adult and children patients has been growing exponentially over the last 20 years. Numerous factors in pediatriac intensive care unit (PICU) patients may contribute to intestinal dysbiosis, which subsequently promotes the pathobiota's growth. Currently, lactobacillus and bifidobacterium species are mainly used to prevent the development of systemic diseases due to the subverted microbiome, followed by streptococcus, enterococcus, propionibacterium, bacillus and Escherichia coli, Lactobacillus rhamnosus GG, and Lactobacillus reuteri DSM 17938. The aim of this article is to review the scientific literature for further confirmation of the importance of the usage of probiotics in intensive care unit (ICU) patients, especially in the pediatric population. A progressive increase in nosocomial infections, especially nosocomial bloodstream infections, has been observed over the last 30 years. The World Health Organization (WHO) reported that the incidence of nosocomial infections in PICUs was still high and ranged between 5% and 10%. Petrof et al. was one of the first to demonstrate the efficacy of probiotics for preventing systemic diseases in ICU patients. Recently, however, the use of probiotics with different lactobacillus spp. has been shown to cause a decrease of pro-inflammatory cytokines and an increase in anti-inflammatory cytokines. In addition, in some studies, the use of probiotics, in particular the mix of Lactobacillus and Bifidobacterium reduces the incidence of ventilator-associated pneumonia (VAP) in PICU patients requiring mechanical ventilation. In abdominal infections, there is no doubt at all about the usefulness of using Lactobacillus spp probiotics, which help to treat ICU-acquired diarrhoea episodes as well as in positive blood culture for candida spp. Despite the importance of using probiotics being supported by various studies, their use is not yet part of the standard protocols to which all doctors must adhere. In the meantime, while waiting for protocols to be drawn up as soon as possible for use in PICUs, routine use could certainly stimulate the intestine's immune defences. Though it is still too early to say, they could be considered the drugs of the future.

Review: Lessons Learned From Clinical Trials Using Antimicrobial Peptides (AMPs)

Antimicrobial peptides (AMPs) or host defense peptides protect the host against various pathogens such as yeast, fungi, viruses and bacteria. AMPs also display immunomodulatory properties ranging from the modulation of inflammatory responses to the promotion of wound healing. More interestingly, AMPs cause cell disruption through non-specific interactions with the membrane surface of pathogens. This is most likely responsible for the low or limited emergence of bacterial resistance against many AMPs. Despite the increasing number of antibiotic-resistant bacteria and the potency of novel AMPs to combat such pathogens, only a few AMPs are in clinical use. Therefore, the current review describes (i) the potential of AMPs as alternatives to antibiotics, (ii) the challenges toward clinical implementation of AMPs and (iii) strategies to improve the success rate of AMPs in clinical trials, emphasizing the lessons we could learn from these trials.

Effect of Heat-killed Lactobacillus casei DKGF7 on a Rat Model of Irritable Bowel Syndrome

Non-viable bacteria, referred to as “paraprobiotics,” have attracted attention as potentially safer alternatives to probiotics. The aim of this study was to investigate the efficacy of heat-killed Lactobacillus casei DKGF7 on the symptomatic improvement of irritable bowel syndrome (IBS) in a rat disease model and to elucidate the underlying mechanisms that contribute to the beneficial effects of heat-killed probiotics. Seven male Wistar rats were induced with IBS by restraint stress and administered heat-killed L. casei DKGF7 for four weeks and then compared with seven rats in the control group. Stool consistency measured four weeks after initial treatment was the primary outcome measure. To investigate the mechanism of action of the heat-killed bacteria on IBS, we measured serum corticosterone levels, inflammatory cytokines in colon tissue, and expression of tight junction proteins (TJPs) in the epithelium. The treatment group showed significantly better stool consistency scores than the control group at week 4, as well as at every measured time point (all p values < 0.05). The treatment group showed lower serum corticosterone levels, lower colonic inflammatory cytokine levels, and higher expression of TJPs compared with the control group. Paraprobiotics such as heat-killed L. casei DKGF7 can improve stool consistency in a rat IBS model, which may indicate a potential therapeutic strategy for IBS treatment.

The Effect of Probiotics on Bacterial Pneumonia

Background: Pneumonia, as a fairly prevalent illness, is the main cause of hospital mortality. The major cause of mortality and morbidity of pneumonia is due to bacteria. The presence of multi-drug resistant pathogens and no response to treatment have aroused considerable interest in the use of probiotic components to prevent infections. Objectives: Given that few studies have evaluated the efficacy of probiotics in reducing bacterial pneumonia, the current aimed to evaluate the role of probiotics in decreasing pneumonia. Methods: This double-blind, randomized clinical trial study was conducted on 100 patients diagnosed with bacterial pneumonia in Shahid Beheshti Hospital, Kashan, Iran, during 2018. Patients were randomly classified into two groups (n = 50). One group (case) received two sachets of probiotic/daily for five days, and another group (control) received placebo. Moreover, patients in both groups received the same treatment protocol. All data were extracted from medical records. Chi-square test and independent t-test were used for analysis of data. P < 0.05 was considered statistically significant. Results: No significant difference was seen between case and control groups regarding age, gender, and duration of symptoms before hospitalization (P > 0.05), which implies a completely random classification of two groups. The mean duration of hospitalization, dyspnea, tachypnea, cough, fever, and crackles was significantly decreased in the case group compared to the control group (P < 0.05). Conclusion: The use of probiotics can be effective in reducing the duration of dyspnea, tachypnea, cough, fever, and length of hospitalization. Therefore, probiotics may be considered a promising treatment for the development of new anti-infectious therapy. In addition, the usage of probiotics along with antibiotics is suggested for decreasing pneumonia complications and improving the efficacy of therapy.

Preventive Effect of Probiotics on Ventilator-Associated Pneumonia: A Meta-analysis of 2428 Patients

BACKGROUND

Researchers had contradictory conclusions about the role of probiotics in preventing ventilator-associated pneumonia (VAP), which has led to the controversial use of probiotics in mechanically ventilated patients.

OBJECTIVE

To explore the efficacy and safety of probiotics in preventing VAP.

METHODS

A literature search was conducted in 7 medical databases. Two investigators assessed literature quality independently and collected data. The primary outcome was the incidence of VAP. Secondary outcomes included 16 measures. Sensitivity analysis and subgroup and meta-regression analyses were performed to analyze the source of heterogeneity. P values <0.05 were considered statistically significant, and CIs were set at 95%. A random-effects model was set when I² <50%, otherwise a fixed-effects model was used.

RESULTS

A total of 20 randomized controlled studies with a total of 2428 patients were analyzed. Pooled results showed positive effects of probiotics on the reduction of VAP incidence (risk ratio [RR] = 0.672; P < 0.001; I² = 11.3%), length of ICU stay (WMD = -1.417; P = 0.012; I² = 90.7%), oropharyngeal (RR = 0.866; P = 0.031; I² = 12.4%) and gastric (RR = 0.645; P < 0.001; I² = 30.2%) colonization.

CONCLUSIONS AND RELEVANCE

Probiotics can reduce the incidence of VAP and reduce oropharyngeal and gastric bacterial colonization. The results also suggest that probiotics do not cause adverse effects.

Intestinal permeability changes with bacterial translocation as key events modulating systemic host immune response to SARS-CoV-2: A working hypothesis

The microbiota-gut-liver-lung axis plays a bidirectional role in the pathophysiology of a number of infectious diseases. During the course of severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1) and 2 (SARS-CoV-2) infection, this pathway is unbalanced due to intestinal involvement and systemic inflammatory response. Moreover, there is convincing preliminary evidence linking microbiota-gut-liver axis perturbations, proinflammatory status, and endothelial damage in noncommunicable preventable diseases with coronavirus disease 2019 (Covid-19) severity. Intestinal damage due to SARS-CoV-2 infection, systemic inflammation-induced dysfunction, and IL-6-mediated diffuse vascular damage may increase intestinal permeability and precipitate bacterial translocation. The systemic release of damage- and pathogen-associated molecular patterns (e.g. lipopolysaccharides) and consequent immune-activation may in turn auto-fuel vicious cycles of systemic inflammation and tissue damage. Thus, intestinal bacterial translocation may play an additive/synergistic role in the cytokine release syndrome in Covid-19. This review provides evidence on gut-liver axis involvement in Covid-19 as well as insights into the hypothesis that intestinal endotheliitis and permeability changes with bacterial translocation are key pathophysiologic events modulating systemic inflammatory response. Moreover, it presents an overview of readily applicable measures for the modulation of the gut-liver axis and microbiota in clinical practice.

Impact of microbiome-based interventions on gastrointestinal pathogen colonization in the intensive care unit

In the intensive care unit (ICU), colonization of the gastrointestinal tract by potentially pathogenic bacteria is common and often precedes clinical infection. Though effective in the short term, traditional antibiotic-based decolonization methods may contribute to rising resistance in the long term. Novel therapies instead focus on restoring gut microbiome equilibrium to achieve pathogen colonization resistance. This review summarizes the existing data regarding microbiome-based approaches to gastrointestinal pathogen colonization in ICU patients with a focus on prebiotics, probiotics, and synbiotics.

Evidence map on the contributions of traditional, complementary and integrative medicines for health care in times of COVID-19

Background

Due to the pandemic, there is a significant interest in the therapeutic resources linked to TCIM to support potentially therapeutic research and intervention in the management of Coronavirus - 19 (COVID-19). At the date of this evidence map´s publication, there is no evidence of specific treatments for COVID-19. This map organizes information about symptoms management (especially on dimensions related to mental health and mild viral respiratory infections, as well as immune system strengthening and antiviral activity).

Method

This evidence map applies methodology developed by Latin American and Caribbean Center on Health Sciences Information based on the 3iE evidence gap map. A search was performed in the Traditional, Complementary and Integrative Medicine Virtual Health Library and PubMed, using the MeSH and DeCS terms for respiratory viral diseases associated with epidemics, COVID-19 symptoms, relevant mental health topics, pharmacological and non-pharmacological interventions related to TCIM.

Results

For the map, 126 systematic reviews and controlled clinical studies were characterized, distributed in a matrix with 62 interventions (18 phytotherapy, 9 mind-body therapies, 11 traditional Chinese medicine, 7 homeopathic and anthroposophic dynamized medicines and 17 supplements), and 67 outcomes (14 immunological response, 23 mental health, 25 complementary clinical management of the infection and 5 other).

Conclusion

The map presents an overview of possible TCIM contributions to various dimensions of the COVID-19 pandemic, especially in the field of mental health, and it is directed to researchers and health professionals specialized in TCIM. Most of the antiviral activity outcomes described in this map refers to respiratory viruses in general, and not specifically to SARS-CoV-2 (Severe Acute Respiratory Syndrome CoronaVirus 2). This information may be useful to guide new research, but not necessarily to support a therapeutic recommendation. Finally, any suspicion of COVID-19 infection should follow the protocols recommended by the health authorities of each country/region.

Gut Microbiota and Lung Injury

Gut microbiota are known to impact multiple organs including the lung. The cross talk between gut microbes and lungs, termed as the "gut-lung axis," is vital for immune response and homeostasis in the airways. In this chapter, we summarized the coordinated development of microorganisms in the gut and lung, exogenous and endogenous factors related to the cross talk, the mechanisms of the gut-lung axis and their dysbiosis in lung diseases. Although the current understanding of the gut-lung axis is in its infancy, several gut microbiota-associated strategies have been designed to treat and prevent lung diseases.

Study protocol for the safety and efficacy of probiotic therapy on days alive and out of hospital in adult ICU patients: the multicentre, randomised, placebo-controlled Restoration Of gut microflora in Critical Illness Trial (ROCIT)

INTRODUCTION

The effect of early and sustained administration of daily probiotic therapy on patients admitted to the intensive care unit (ICU) remains uncertain.

METHODS AND ANALYSIS

The Restoration Of gut microflora in Critical Illness Trial (ROCIT) study is a multicentre, randomised, placebo-controlled, parallel-group, two-sided superiority trial that will enrol 220 patients in five ICUs. Adult patients who are within 48 hours of admission to an ICU and are expected to require intensive care beyond the next calendar day will be randomised in a 1:1 ratio to receive early and sustained Lactobacillus plantarum 299v probiotic therapy in addition to usual care or placebo in addition to usual care. The primary endpoint is days alive and out of hospital to day 60.

ETHICS AND DISSEMINATION

ROCIT has been approved by the South Metropolitan Health Service Human Research Ethics Committee (ref: RGS00000004) and the St John of God Health Care Human Research Ethics Committee (ref: 1183). The trial results will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

Australian and New Zealand Clinical Trials Registry (ANZCTR12617000783325); Pre-results.

Microbiome: what intensivists should know

The standard conditions of critical illness (including sepsis, acute respiratory distress syndrome, and multiorgan failure) cause enormous global mortality and a growing economic burden. Increasing evidence suggests that critical illness may be associated with loss of commensal microbes and overgrowth of potentially pathogenic and inflammatory bacteria. This state could be associated with poor outcomes. Therefore, microbiota-targeted interventions are potentially attractive novel treatment options. Although the precise mechanisms of microbiome-directed treatments such as prebiotics, probiotics, and fecal microbiota transplantation remain to be determined, they can be utilized in the Intensive Care Unit (ICU) setting. The current review aims to offer intensivists an evidenced-based approach on what we currently know about the role of the microbiome in critical illness and how the microbiome could be targeted in the clinical practice to improve ICU-related outcomes.

Clinical nutrition for the gastroenterologist: bedside strategies for feeding the hospitalized patient

PURPOSE OF REVIEW

The timing, advancement, and use of appropriate monitors determine whether the hospitalized patient experiences the full benefit of nutritional therapy. This article reviews management strategies in delivering the optimal nutrition regimen capable of improving outcomes in the hospitalized patient.

RECENT FINDINGS

Enteral nutrition should be initiated in the first 24-36 h after admission. Determination of nutritional risk helps guide the urgency with which nutritional therapy is provided and predicts the likelihood for difficulties in delivering the prescribed regimen. Feeds should be advanced slowly over 3-4 days to meet 70-80% of goal for calories (20 kcal/kg/day) and 100% for protein (2.0 gm/kg/day). Reaching protein goals early on may be more important than achieving energy goals. Patients should be monitored for hemodynamic stability, evidence of refeeding syndrome, and tolerance in the setting of gastrointestinal dysfunction. Parenteral nutrition should be utilized in select high-risk patients where the feasibility of full enteral nutrition is questioned.

SUMMARY

Timing with early initiation of enteral nutrition, avoidance of overfeeding, and step-wise advancement of feeds are required to safely realize the benefits of such therapy.

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.

Dysbiosis of the intestinal microbiota in neurocritically ill patients and the risk for death

Background

Despite the essential functions of the intestinal microbiota in human physiology, little has been reported about the microbiome in neurocritically ill patients. This investigation aimed to evaluate the characteristics of the gut microbiome in neurocritically ill patients and its changes after admission. Furthermore, we investigated whether the characteristics of the gut microbiome at admission were a risk factor for death within 180 days.

Methods

This prospective observational cohort study included neurocritically ill patients admitted to the neurological intensive care unit of a large university-affiliated academic hospital in Guangzhou. Faecal samples were collected within 72 h after admission (before antibiotic treatment) and serially each week. Healthy volunteers were recruited from a community in Guangzhou. The gut microbiome was monitored via 16S rRNA gene sequence analysis, and the associations with the clinical outcome were evaluated by a Cox proportional hazards model.

Results

In total, 98 patients and 84 age- and sex-matched healthy subjects were included in the analysis. Compared with healthy subjects, the neurocritically ill patients exhibited significantly different compositions of intestinal microbiota. During hospitalization, the α-diversity and abundance of Ruminococcaceae and Lachnospiraceae decreased significantly over time in patients followed longitudinally. The abundance of Enterobacteriaceae was positively associated with the modified Rankin Scale at discharge. In the multivariate Cox regression analysis, Christensenellaceae and Erysipelotrichaceae were associated with an increased risk of death. The increases in intestinal Enterobacteriales and Enterobacteriaceae during the first week in the neurological intensive care unit were associated with increases of 92% in the risk of 180-day mortality after adjustments.

Conclusions

This analysis of the gut microbiome in 98 neurocritically ill patients indicates that the gut microbiota composition in these patients differs significantly from that in a healthy population and that the magnitude of this dysbiosis increases during hospitalization in a neurological intensive care unit. The gut microbiota characteristics seem to have an impact on patients’ 180-day mortality. Gut microbiota analysis could hopefully predict outcome in the future.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2488-4) contains supplementary material, which is available to authorized users.

Drug Prevention and Control of Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) is one of the most prevalent and serious complications of mechanical ventilation, which is considered a common nosocomial infection in critically ill patients. There are some great options for the prevention of VAP: (i) minimize ventilator exposure; (ii) intensive oral care; (iii) aspiration of subglottic secretions; (iv) maintain optimal positioning and encourage mobility; and (v) prophylactic probiotics. Furthermore, clinical management of VAP depends on appropriate antimicrobial therapy, which needs to be selected based on individual patient factors, such as previous antibacterial therapy, history of hospitalization or mechanical ventilation, and bacterial pathogens and antibiotic resistance patterns. In fact, antibiotic resistance has exponentially increased over the last decade, and the isolation of a multidrug-resistant (MDR) pathogen has been identified as an independent predictor of inadequate initial antibiotic therapy and which is significantly associated with increased mortality. Multiple attempts were used in the treatment of VAP, such as novel antibacterial agents, inhaled antibiotics and monoclonal antibodies. In this review, we summarize the current therapeutic options for the prevention and treatment of VAP, aiming to better management of VAP in clinical practice.

Susceptibility to antibiotics in isolates of Lactobacillus plantarum RAPD-type Lp299v, harvested from antibiotic treated, critically ill patients after administration of probiotics

Recultured Lactobacillus plantarum 299v-like strains were tested regarding antibiotic susceptibility, and no decrease was detected. Antibiotics are frequently used to treat patients in intensive care units (ICUs) and are associated with a significant risk of selection of resistant bacterial strains. In particular, it is possible that genetic transfer of antibiotic resistance to the resident gastrointestinal flora, as well as to administered probiotics, may be increased in the ICU setting. The aim of the present investigation was to detect possible changes in antimicrobial susceptibility in reisolates of the probiotic strain Lactobacillus plantarum 299v (Lp299v) given to antibiotic treated, critically ill patients. Lp299v-like strains were identified in cultures of biopsies and fecal samples from 32 patients given the probiotic strain enterally in two previous ICU studies. The patients received a variety of antibiotics. Isolates with the same genomic RAPD profile (RAPD-type) as Lp299v were obtained to enable monitoring of antibiotic susceptibility by E-tests. Forty-two isolates, collected throughout the course of illness, were tested against 22 different antibiotics. No obvious decrease in susceptibility was found for 21 of the tested antibiotics. There was a tendency toward decreased susceptibility to ampicillin. The stable antibiotic susceptibility profiles of the Lp299v-like isolates studied here suggests this probiotic is less likely to acquire resistance when administered to critically ill patients treated with broad-spectrum antibiotics.

The Effects of Gastrointestinal Function on the Incidence of Ventilator-associated Pneumonia in Critically Ill Patients

Objective

To investigate the effect of gastrointestinal function on the incidence of ventilator-associated pneumonia (VAP) in critically ill patients.

Methods

From August 2012 to June 2016, 160 critically ill patients in the ICU (Intensive Care Unit) of our hospital were selected as the research group; patients were divided equally into an observation group and a control group, 80 patients in each group, based on the random draw envelope principle. The control group was given a nasogastric tube for gastric feeding, the observation group was given a dual lumen gastrointestinal enteral device for gastric feeding; the two groups’ enteral nutrition observation time was 7d; any changes in patient condition and prognosis were recorded.

Results

The pH value of gastric juice in the control group and the observation group was 6.13±1.38 and 4.01±1.83, respectively: the pH for the observation group was significantly lower than that of the control group (t=4.982, P<0.05). The incidence of VAP in the observation group and the control group was 2.5% and 12.5%, respectively: the VAP for the observation group was significantly lower than that of the control group (P<0.05). The serum levels of pre-albumin and albumin after feeding in the two groups were significantly higher than before feeding (P<0.05); the serum levels of pre-albumin and albumin in the observation group after feeding were significantly higher than those in the control group (P<0.05). The mechanical ventilation time and ICU length of stay in the observation group were 9.12±2.13 days and 12.76±1.98 days, respectively, significantly lower than those of the control group of 10.56±2.89 days and 16.33±2.11 days (P<0.05).

Conclusion

Obstacles to gastrointestinal function in critically ill ICU patients are common; enteral gastric feeding by dual lumen gastrointestinal for can improve the patient’s nutritional status, promote and maintain the normal pH value of gastric juice, thereby reducing the incidence of VAP through rehabilitation of patients.

Consensus and contentious statements on the use of probiotics in clinical practice: A south east Asian gastro-neuro motility association working team report

The concept of consuming microorganisms in the treatment of a medical condition and in health maintenance has gained much attraction, giving rise to an abundance of medical claims and of health supplements. This study identified relevant clinical questions on the therapeutic use of probiotics and reviewed the literature in irritable bowel syndrome, inflammatory bowel disease, impaired intestinal immunity, liver disease, intestinal infections, and common childhood digestive disorders. Statements were developed to address these clinical questions. A panel of experienced clinicians was tasked to critically evaluate and debate the available data. Both consensus and contentious statements are presented to provide to clinicians a perspective on the potential of probiotics and importantly their limitations.

Rapid gastrointestinal loss of Clostridial Clusters IV and XIVa in the ICU associates with an expansion of gut pathogens

Commensal gastrointestinal bacteria resist the expansion of pathogens and are lost during critical illness, facilitating pathogen colonization and infection. We performed a prospective, ICU-based study to determine risk factors for loss of gut colonization resistance during the initial period of critical illness. Rectal swabs were taken from adult ICU patients within 4 hours of admission and 72 hours later, and analyzed using 16S rRNA gene sequencing and selective culture for vancomycin-resistant Enterococcus (VRE). Microbiome data was visualized using principal coordinate analyses (PCoA) and assessed using a linear discriminant analysis algorithm and logistic regression modeling. 93 ICU patients were analyzed. At 72 hours following ICU admission, there was a significant decrease in the proportion of Clostridial Clusters IV/XIVa, taxa that produce short chain fatty acids (SCFAs). At the same time, there was a significant expansion in Enterococcus. Decreases in Cluster IV/XIVa Clostridia were associated with loss of gut microbiome colonization resistance (reduced diversity and community stability over time). In multivariable analysis, both decreased Cluster IV/XIVa Clostridia and increased Enterococcus after 72 hours were associated with receipt of antibiotics. Cluster IV/XIVa Clostridia, although a small fraction of the overall gastrointestinal microbiome, drove distinct clustering on PCoA. During initial treatment for critical illness, there was a loss of Cluster IV/XIVa Clostridia within the distal gut microbiome which associated with an expansion of VRE and with a loss of gut microbiome colonization resistance. Receipt of broad-spectrum antibiotics was associated with these changes.

Incidences of Pseudomonas aeruginosa-Associated Ventilator-Associated Pneumonia within Studies of Respiratory Tract Applications of Polymyxin: Testing the Stoutenbeek Concurrency Postulates

Regimens containing topical polymyxin appear highly effective at preventing ventilator-associated pneumonia (VAP) overall and, more so, VAP caused by Gram-negative bacteria. However, Stoutenbeek's postulates that VAP incidences within studies of topical antibiotics depend on the context of whether the component (control and intervention) groups of each study were concurrent versus nonconcurrent remain untested. The literature was searched for concurrent control (CC) versus nonconcurrent control (NCC) designed studies of respiratory tract applications of topical polymyxin to mechanically ventilated (MV) patients that reported incidences of Pseudomonas-associated ventilator-associated pneumonia (PsVAP). Studies of various interventions other than topical polymyxin (nonpolymyxin studies) served to provide additional points of reference. The PsVAP incidences within the component groups of all studies were benchmarked against groups from observational studies. This was undertaken by meta-regression using generalized estimating equation methods. Dot plots, caterpillar plots, and funnel plots enable visual benchmarking. The PsVAP benchmark (and 95% confidence interval [CI]) derived from 102 observational groups is 4.6% (4.0 to 5.3%). In contrast, the mean PsVAP within NCC polymyxin intervention groups (1.6%; CI, 1.0 to 4.5%) is lower than that of all other component group categories. The mean PsVAP within CC polymyxin control groups (9.9%; CI, 7.6 to 12.8%) is higher than that of all other component group categories. The PsVAP incidences of control and intervention groups of studies of respiratory tract applications of polymyxin are dependent on whether the groups were within a concurrent versus nonconcurrent study. Stoutenbeek's concurrency postulates are validated.

Antibiotic treatment-induced secondary IgA deficiency enhances susceptibility to Pseudomonas aeruginosa pneumonia

Broad-spectrum antibiotics are widely used with patients in intensive care units (ICUs), many of whom develop hospital-acquired infections with Pseudomonas aeruginosa. Although preceding antimicrobial therapy is known as a major risk factor for P. aeruginosa-induced pneumonia, the underlying mechanisms remain incompletely understood. Here we demonstrate that depletion of the resident microbiota by broad-spectrum antibiotic treatment inhibited TLR-dependent production of a proliferation-inducing ligand (APRIL), resulting in a secondary IgA deficiency in the lung in mice and human ICU patients. Microbiota-dependent local IgA contributed to early antibacterial defense against P. aeruginosa. Consequently, P. aeruginosa-binding IgA purified from lamina propria culture or IgA hybridomas enhanced resistance of antibiotic-treated mice to P. aeruginosa infection after transnasal substitute. Our study provides a mechanistic explanation for the well-documented risk of P. aeruginosa infection following antimicrobial therapy, and we propose local administration of IgA as a novel prophylactic strategy.

Role of the microbiome, probiotics, and 'dysbiosis therapy' in critical illness

PURPOSE OF REVIEW

Loss of 'health-promoting' microbes and overgrowth of pathogenic bacteria (dysbiosis) in ICU is believed to contribute to nosocomial infections, sepsis, and organ failure (multiple organ dysfunction syndrome). This review discusses new understanding of ICU dysbiosis, new data for probiotics and fecal transplantation in ICU, and new data characterizing the ICU microbiome.

RECENT FINDINGS

ICU dysbiosis results from many factors, including ubiquitous antibiotic use and overuse. Despite advances in antibiotic therapy, infections and mortality from often multidrug-resistant organisms (i.e., Clostridium difficile) are increasing. This raises the question of whether restoration of a healthy microbiome via probiotics or other 'dysbiosis therapies' would be an optimal alternative, or parallel treatment option, to antibiotics. Recent clinical data demonstrate probiotics can reduce ICU infections and probiotics or fecal microbial transplant (FMT) can treat Clostridium difficile. This contributes to recommendations that probiotics should be considered to prevent infection in ICU. Unfortunately, significant clinical variability limits the strength of current recommendations and further large clinical trials of probiotics and FMT are needed. Before larger trials of 'dysbiosis therapy' can be thoughtfully undertaken, further characterization of ICU dysbiosis is needed. To addressing this, we conducted an initial analysis demonstrating a rapid and marked change from a 'healthy' microbiome to an often pathogen-dominant microbiota (dysbiosis) in a broad ICU population.

SUMMARY

A growing body of evidence suggests critical illness and ubiquitous antibiotic use leads to ICU dysbiosis that is associated with increased ICU infection, sepsis, and multiple organ dysfunction syndrome. Probiotics and FMT show promise as ICU therapies for infection. We hope future-targeted therapies using microbiome signatures can be developed to correct 'illness-promoting' dysbiosis to restore a healthy microbiome post-ICU to improve patient outcomes.

Paradoxical Acinetobacter-associated ventilator-associated pneumonia incidence rates within prevention studies using respiratory tract applications of topical polymyxin: benchmarking the evidence base

BACKGROUND

Regimens containing topical polymyxin appear to be more effective in preventing ventilator-associated pneumonia (VAP) than other methods.

AIM

To benchmark the incidence rates of Acinetobacter-associated VAP (AAVAP) within component (control and intervention) groups from concurrent controlled studies of polymyxin compared with studies of various VAP prevention methods other than polymyxin (non-polymyxin studies).

METHODS

An AAVAP benchmark was derived using data from 77 observational groups without any VAP prevention method under study. Data from 41 non-polymyxin studies provided additional points of reference. The benchmarking was undertaken by meta-regression using generalized estimating equation methods.

RESULTS

Within 20 studies of topical polymyxin, the mean AAVAP was 4.6% [95% confidence interval (CI) 3.0-6.9] and 3.7% (95% CI 2.0-5.3) for control and intervention groups, respectively. In contrast, the AAVAP benchmark was 1.5% (95% CI 1.2-2.0). In the AAVAP meta-regression model, group origin from a trauma intensive care unit (+0.55; +0.16 to +0.94, P = 0.006) or membership of a polymyxin control group (+0.64; +0.21 to +1.31, P = 0.023), but not membership of a polymyxin intervention group (+0.24; -0.37 to +0.84, P = 0.45), were significant positive correlates.

CONCLUSIONS

The mean incidence of AAVAP within the control groups of studies of topical polymyxin is more than double the benchmark, whereas the incidence rates within the groups of non-polymyxin studies and, paradoxically, polymyxin intervention groups are more similar to the benchmark. These incidence rates, which are paradoxical in the context of an apparent effect against VAP within controlled trials of topical polymyxin-based interventions, force a re-appraisal.

Synbiotics for Improved Human Health: Recent Developments, Challenges, and Opportunities

Research on combining pro- and prebiotics as synbiotics to enhance human and animal health has accelerated in the past 10 years, including many clinical trials that have assessed a diverse range of synbiotic formulations. In this review, we summarize these studies as well as the commercial applications of synbiotics that are available. In particular, we critically assess the claimed health benefits of synbiotic applications and the ecological and therapeutic factors to consider when designing synbiotics and discuss the implications of these concepts for future research in this field.

Characterizing the gut microbiome in trauma: significant changes in microbial diversity occur early after severe injury

Background

Recent studies have demonstrated the vital influence of commensal microbial communities on human health. The central role of the gut in the response to injury is well described; however, no prior studies have used culture-independent profiling techniques to characterize the gut microbiome after severe trauma. We hypothesized that in critically injured patients, the gut microbiome would undergo significant compositional changes in the first 72 hours after injury.

Methods

Trauma stool samples were prospectively collected via digital rectal examination at the time of presentation (0 hour). Patients admitted to the intensive care unit (n=12) had additional stool samples collected at 24 hours and/or 72 hours. Uninjured patients served as controls (n=10). DNA was extracted from stool samples and 16S rRNA-targeted PCR amplification was performed; amplicons were sequenced and binned into operational taxonomic units (OTUs; 97% sequence similarity). Diversity was analyzed using principle coordinates analyses, and negative binomial regression was used to determine significantly enriched OTUs.

Results

Critically injured patients had a median Injury Severity Score of 27 and suffered polytrauma. At baseline (0 hour), there were no detectable differences in gut microbial community diversity between injured and uninjured patients. Injured patients developed changes in gut microbiome composition within 72 hours, characterized by significant alterations in phylogenetic composition and taxon relative abundance. Members of the bacterial orders Bacteroidales, Fusobacteriales and Verrucomicrobiales were depleted during 72 hours, whereas Clostridiales and Enterococcus members enriched significantly.

Discussion

In this initial study of the gut microbiome after trauma, we demonstrate that significant changes in phylogenetic composition and relative abundance occur in the first 72 hours after injury. This rapid change in intestinal microbiota represents a critical phenomenon that may influence outcomes after severe trauma. A better understanding of the nature of these postinjury changes may lead to the ability to intervene in otherwise pathological clinical trajectories.

Level of evidence

III

Study type

Prognostic/epidemiological

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

Background and Objective: Ventilator-associated pneumonia (VAP) is still an important cause of morbidity and mortality in mechanically ventilated patients. The efficacy of the probiotics for preventing VAP is still controversial. Present study was conducted to comprehensively evaluate the effect of probiotics on VAP prevention in mechanically ventilated patients. Methods: PubMed, Embase, and CENTRAL were searched up to September 2016. Eligible trials designed with randomized controlled trials (RCTs) comparing probiotics with control in mechanically ventilated patients were included. Risk ratios (RRs) and mean differences (MDs) with 95% confidence intervals (CIs) were estimated with fixed or random effects models. Trial sequential analysis (TSA) was performed using TSA 0.9beta software. Results: Thirteen RCTs (N = 1969) were included. Overall, probiotics were associated with reduced incidence of VAP (RR = 0.73, 95% CI = 0.60-0.89; P = 0.002), which was confirmed by TSA (TSA adjusted 95% CI = 0.55-0.96). However, no significant difference was observed in 90-day mortality (RR = 1.00, 95% CI = 0.72-1.37; P = 0.99), overall mortality (RR = 0.84, 95% CI = 0.70-1.02; P = 0.09), 28-day mortality (RR = 1.06, 95% CI = 0.72-1.57; P = 0.99), intensive care unit (ICU) mortality (RR = 0.97, 95% CI = 0.74-1.27; P = 0.82), hospital mortality (RR = 0.81, 95% CI = 0.65-1.02; P = 0.07), diarrhea (RR = 0.99, 95% CI = 0.83-1.19; P = 0.92), length of ICU stay (MD = -2.40 days, 95% CI = -6.75 to 1.95; P = 0.28), length of hospital stay (MD = -1.34 days, 95% CI = -6.21 to 3.54; P = 0.59), and duration of mechanical ventilation (MD = -3.32 days, 95% CI = -6.74 to 0.09; P = 0.06). Conclusions: In this meta-analysis, we found that probiotics could reduce the incidence of VAP in mechanically ventilated patients. It seems likely that probiotics provide clinical benefits for mechanically ventilated patients.

Sporulated Bacillus as alternative treatment for diarrhea of hospitalized adult patients under enteral nutrition: A pilot randomized controlled study

BACKGROUND & AIMS

Among hospitalized patients receiving enteral nutrition (EN), malnutrition and antibiotic use are some of the most common causes of diarrhea. Prebiotics and probiotics agents have been used for treatment of diarrhea in such patients. The aim of this study was to assess the efficacy of a sporulated Bacillus strain (Bacillus cereus A 05), compared to a control group using a prebiotic (soluble fiber), in reducing diarrhea in patients receiving EN and antibiotic therapy.

METHODS

Patients with diarrhea receiving EN were randomized to receive either B. cereus (study group) or soluble fiber (control group) for five days. The group treated with B. cereus received 4 vials with 5 mL × 10⁶ every 6 h. The control group treated with fiber received 10 g of soluble fiber every 8 h. Data assessed were serum albumin, nutrition status through Subjective Global Assessment (SGA), antibiotic use and osmolality (normal or hyperosmolar) of the tube feeding diets.

RESULTS

Twenty-nine patients were treated in each group. There was no significant difference between the groups regarding age, serum albumin, SGA score, dietary osmolality and antibiotic use. There was no significant difference between groups in ceasing diarrhea. However, the group treated with B. cereus took fewer days to cease diarrhea (2.5 ± 1.3 versus 3.7 ± 1.1 days, p = 0.011). Specifically, in the group treated with B. cereus A 05, malnourished patients did better than non-malnourished patients regarding diarrhea cessation (100% versus 25%, p < 0.001).

CONCLUSIONS

B. cereus A 05 was more effective than fiber in reducing diarrhea among patients under EN and antibiotic therapy and was more effective among malnourished patients.

The function of probiotics on the treatment of ventilator-associated pneumonia (VAP): facts and gaps

Probiotics have been used for centuries in making fermented dairy products. The health benefits related to probiotics consumption are well recognized and they are generally regarded as safe (GRAS). Their therapeutic effects are due to the production of a variety of antimicrobial compounds, such as short-chain fatty acids, organic acids (such as lactic, acetic, formic, propionic and butyric acids), ethanol, hydrogen peroxide and bacteriocins. Ventilator-associated pneumonia (VAP) is a nosocomial infection associated with high mortality in intensive care units. VAP can result from endotracheal intubation and mechanical ventilation. These interventions increase the risk of infection as patients lose the natural barrier between the oropharynx and the trachea, which in turn facilitates the entry of pathogens through the aspiration of oropharyngeal secretions containing bacteria into the lung. In order to prevent this, probiotics have been used extensively against VAP. This review is an update containing information extracted from recent studies on the use of probiotics to treat VAP. In addition, probiotic safety, the therapeutic properties of probiotics, the probiotic strains used and the action of the probiotics mechanism are reviewed. Furthermore, the therapeutic effects of probiotic treatment procedures for VAP are compared to those of antibiotics. Finally, the influences of bacteriocin on the growth of human pathogens, and the side-effects and limitations of using probiotics for the treatment of VAP are addressed.

The Shift of an Intestinal "Microbiome" to a "Pathobiome" Governs the Course and Outcome of Sepsis Following Surgical Injury

Sepsis following surgical injury remains a growing and worrisome problem following both emergent and elective surgery. Although early resuscitation efforts and prompt antibiotic therapy have improved outcomes in the first 24 to 48  h, late onset sepsis is now the most common cause of death in modern intensive care units. This time shift may be, in part, a result of prolonged exposure of the host to the stressors of critical illness which, over time, erode the health promoting intestinal microbiota and allow for virulent pathogens to predominate. Colonizing pathogens can then subvert the immune system and contribute to the deterioration of the host response. Here, we posit that novel approaches integrating the molecular, ecological, and evolutionary dynamics of the evolving gut microbiome/pathobiome during critical illness are needed to understand and prevent the late onset sepsis that develops following prolonged critical illness.

Preventing Ventilator-Associated Infections

Mechanical ventilator use is fraught with risk of complications. Ventilator-associated pneumonia (VAP) is a common complication that prolongs stays on the ventilator and increases mortality and costs. The Centers for Disease Control and Prevention recommend the use of the term, ventilator-associated event. Prevention and/or interruption of cycle of inflammation, colonization of respiratory tract, and ventilator-associated tracheobronchitis are key to managing VAP. Modifying risk factors using a ventilator bundle is considered standard of care. The contentious factors and the lack of support for early tracheotomy, parenteral nutrition, and monitoring of gastric residuals are also addressed. Finally, the role of ventilator-associated tracheobronchitis in VAP is discussed.

Lactobacillus rhamnosus GG treatment improves intestinal permeability and modulates inflammatory response and homeostasis of spleen and colon in experimental model of Pseudomonas aeruginosa pneumonia

BACKGROUND & AIMS

Recent clinical trials and in vivo models demonstrate probiotic administration can reduce occurrence and improve outcome of pneumonia and sepsis, both major clinical challenges worldwide. Potential probiotic benefits include maintenance of gut epithelial barrier homeostasis and prevention of downstream organ dysfunction due to systemic inflammation. However, mechanism(s) of probiotic-mediated protection against pneumonia remain poorly understood. This study evaluated potential mechanistic targets in the maintenance of gut barrier homeostasis following Lactobacillus rhamnosus GG (LGG) treatment in a mouse model of pneumonia.

METHODS

Studies were performed in 6-8 week old FVB/N mice treated (o.g.) with or without LGG (10⁹ CFU/ml) and intratracheally injected with Pseudomonas aeruginosa or saline. At 4, 12, and 24 h post-bacterial treatment spleen and colonic tissue were collected for analysis.

RESULTS

Pneumonia significantly increased intestinal permeability and gut claudin-2. LGG significantly attenuated increased gut permeability and claudin-2 following pneumonia back to sham control levels. As mucin expression is key to gut barrier homeostasis we demonstrate that LGG can enhance goblet cell expression and mucin barrier formation versus control pneumonia animals. Further as Muc2 is a key gut mucin, we show LGG corrected deficient Muc2 expression post-pneumonia. Apoptosis increased in both colon and spleen post-pneumonia, and this increase was significantly attenuated by LGG. Concomitantly, LGG corrected pneumonia-mediated loss of cell proliferation in colon and significantly enhanced cell proliferation in spleen. Finally, LGG significantly reduced pro-inflammatory cytokine gene expression in colon and spleen post-pneumonia.

CONCLUSIONS

These data demonstrate LGG can maintain intestinal barrier homeostasis by enhancing gut mucin expression/barrier formation, reducing apoptosis, and improving cell proliferation. This was accompanied by reduced pro-inflammatory cytokine expression in the gut and in a downstream organ (spleen). These may serve as potential mechanistic targets to explain LGG's protection against pneumonia in the clinical and in vivo setting.

Probiotic and synbiotic therapy in critical illness: a systematic review and meta-analysis

Background

Critical illness is characterized by a loss of commensal flora and an overgrowth of potentially pathogenic bacteria, leading to a high susceptibility to nosocomial infections. Probiotics are living non-pathogenic microorganisms, which may protect the gut barrier, attenuate pathogen overgrowth, decrease bacterial translocation and prevent infection. The purpose of this updated systematic review is to evaluate the overall efficacy of probiotics and synbiotic mixtures on clinical outcomes in critical illness.

Methods

Computerized databases from 1980 to 2016 were searched. Randomized controlled trials (RCT) evaluating clinical outcomes associated with probiotic therapy as a single strategy or in combination with prebiotic fiber (synbiotics). Overall number of new infections was the primary outcome; secondary outcomes included mortality, ICU and hospital length of stay (LOS), and diarrhea. Subgroup analyses were performed to elucidate the role of other key factors such as probiotic type and patient mortality risk on the effect of probiotics on outcomes.

Results

Thirty trials that enrolled 2972 patients were identified for analysis. Probiotics were associated with a significant reduction in infections (risk ratio 0.80, 95 % confidence interval (CI) 0.68, 0.95, P = 0.009; heterogeneity I² = 36 %, P = 0.09). Further, a significant reduction in the incidence of ventilator-associated pneumonia (VAP) was found (risk ratio 0.74, 95 % CI 0.61, 0. 90, P = 0.002; I² = 19 %). No effect on mortality, LOS or diarrhea was observed. Subgroup analysis indicated that the greatest improvement in the outcome of infections was in critically ill patients receiving probiotics alone versus synbiotic mixtures, although limited synbiotic trial data currently exists.

Conclusion

Probiotics show promise in reducing infections, including VAP in critical illness. Currently, clinical heterogeneity and potential publication bias reduce strong clinical recommendations and indicate further high quality clinical trials are needed to conclusively prove these benefits.