Impact of the administration of probiotics on the incidence of ventilator-associated pneumonia: a meta-analysis of randomized controlled trials

Gut-origin sepsis: evolution of a concept

The concept of bacterial translocation and gut-origin sepsis as a cause of systemic infectious complications and the multiple organ dysfunction syndrome (MODS) in surgical and ICU patients has emerged over the last several decades, although the exact clinical relevance of these phenomena continues to be debated. Thus, the goal of this review is to trace the evolution of gut-origin sepsis and gut-induced MODS and put these disorders and observations into clinical perspective. Additionally, the mechanisms leading to gut-derived complications are explored as well as therapeutic options to limit or prevent these complications. From this work, several major conclusions emerge. First, that bacterial translocation occurs clinically and is responsible for increased infectious complications in patients undergoing major abdominal surgery. However, the phenomenon of bacterial translocation is not sufficient to explain the development of MODS in ICU patients. Instead, the development of MODS in these high-risk patients is likely due to gut injury and the systemic spread of non-microbial, tissue-injurious factors that reach the systemic circulation via the intestinal lymphatics. These observations have resulted in the gut-lymph hypothesis of MODS.

Probiotics for prevention of nosocomial infections: efficacy and adverse effects

PURPOSE OF REVIEW

In this era of increasing antimicrobial resistance, use of probiotics in infection prevention has brought new perspective. However, in 2008 the, until then considered, safe use of probiotics became an important topic after publication of a trial showing excess mortality in patients on probiotic prophylaxis. In this article, we review the concept of infection prevention by probiotics and the present knowledge of the efficacy of probiotics in prevention of infections among patients with abdominal diseases and in intensive care. Safety issues of probiotics will be discussed extensively.

RECENT FINDINGS

Over 30 clinical trials with probiotics to prevent infections have been published, some of which were prematurely stopped recently. Studies with critically ill patients and patients with abdominal diseases showed conflicting results regarding the effects of probiotics on infection rates, as did meta-analyses. These studies are difficult to compare because different probiotics were used which all have different efficacy and safety profiles.

SUMMARY

The efficacy of probiotics in infection prevention among critically ill patients is still not unequivocally determined. The safety profile differs per probiotic strain and should not be generalized towards other strains and patient populations. A well designed and well powered clinical trial with clear endpoints to demonstrate efficacy is warranted.

[Update: studies in intensive care medicine. Results of the last 12 months]

Die Intensivmedizin spielt eine bedeutende Rolle sowohl für den medizinischen als auch den ökonomischen Erfolg eines Krankenhauses. Eine qualitativ hochwertige Intensivmedizin setzt die Kenntnis und die Umsetzung relevanter neuer klinischer Studien voraus. Die vorliegende Arbeit gibt einen Überblick über die wichtigsten intensivmedizinischen Publikationen des Jahres 2010 und der ersten Jahreshälfte von 2011 und ordnet diese im Hinblick auf die jeweilige klinische Relevanz ein. In den Jahren 2010 und 2011 sind zahlreiche randomisierte Studien veröffentlicht worden. Schwerpunkte waren die Therapie des Lungenversagens, die Analgosedierung und die Sepsistherapie.

Synbiotics and probiotics in the critically ill after the PROPATRIA trial

PURPOSE OF REVIEW

Recent clinical trials have furthered our understanding of the role of probiotic and synbiotic therapy across a variety of diverse diseases including antibiotic-associated diarrhea, Clostridium difficile associated diarrhea, acute pancreatitis, ventilator-associated pneumonia, and sepsis among others. Although each of these conditions has implications for critically ill patients, relatively few studies have specifically studied this vulnerable population.

RECENT FINDINGS

One recent clinical trial studying probiotics in severe pancreatitis (the PROPATRIA trial) found an unexpected increase in mortality in probiotic-treated patients. These results stimulated an immediate, extensive, and badly overdue discussion focused on the need for improved safety monitoring during the execution of all clinical trials using probiotics. However, issues with the design, execution, and analysis of PROPATRIA ultimately created more questions than it answered.

SUMMARY

Regardless of technical issues with the study, the increased mortality seen with probiotics cannot be ignored. As a result, various regulatory agencies have clarified their stance on the safety of probiotic research and the legacy of PROPATRIA is increasingly stringent regulation of this fledgling niche.

Strategies for prevention of ventilator-associated pneumonia: bundles, devices, and medications for improved patient outcomes

Ventilator-associated pneumonia is associated with significant patient morbidity, mortality, and increased health care costs. In the current economic climate, it is crucial to implement cost-effective prevention strategies that have proven efficacy. Multiple prevention measures have been proposed by various expert panels. Global strategies have focused on infection control, and reduction of lower airway colonization with bacterial pathogens, intubation, duration of mechanical ventilation, and length of stay in the intensive care unit. Routine use of the Institute for Healthcare Improvement ventilator care bundle is widespread, and has been clearly demonstrated to be an effective method for reducing the incidence of ventilator-associated pneumonia. In this article, we examine specific aspects of the Institute for Healthcare Improvement bundle, better-designed endotracheal tubes, use of antibiotics and probiotics, and treatment of ventilator-associated tracheobronchitis to prevent ventilator-associated pneumonia.

Effects of probiotics on serum levels of Th1/Th2 cytokine and clinical outcomes in severe traumatic brain-injured patients: a prospective randomized pilot study

INTRODUCTION

Traumatic brain injury (TBI) is associated with a profound immunological dysfunction manifested by a severe shift from T-helper type 1 (Th1) to T-helper type 2 (Th2) response. This predisposes patients to infections, sepsis, and adverse outcomes. Probiotic bacteria have been shown to balance the Th1/Th2 cytokines in allergic murine models and patients. For the present study, we hypothesized that the enteral administration of probiotics would adjust the Th1/Th2 imbalance and improve clinical outcomes in TBI patients.

METHODS

We designed a prospective, randomized, single-blind study. Patients with severe TBI and Glasgow Coma Scale scores between 5 and 8 were included, resulting in 26 patients in the control group and 26 patients in the probiotic group. All patients received enteral nutrition via a nasogastric tube within 24 to 48 hours following admission. In addition, the probiotic group received 109 bacteria of viable probiotics per day for 21 days. The associated serum levels of Th1/Th2 cytokines, Acute Physiology and Chronic Health Evaluation (APACHE) II and Sequential Organ Failure Assessment (SOFA) scores, nosocomial infections, length of ICU stay, and 28-day mortality rate were studied.

RESULTS

The patients responded to viable probiotics, and showed a significantly higher increase in serum IL-12p70 and IFNγ levels while also experiencing a dramatic decrease in IL-4 and IL-10 concentrations. APACHE II and SOFA scores were not significantly affected by probiotic treatment. Patients in the probiotic group experienced a decreased incidence of nosocomial infections towards the end of the study. Shorter ICU stays were also observed among patients treated with probiotic therapy. However, the 28-day mortality rate was unaffected.

CONCLUSIONS

The present study showed that daily prophylactic administration of probiotics could attenuate the deviated Th1/Th2 response induced by severe TBI, and could result in a decreased nosocomial infection rate, especially in the late period.

TRIAL REGISTRATION

ChiCTR-TRC-10000835.

Probiotics for disease prevention: a focus on ventilator-associated pneumonia

OBJECTIVE

To summarize published data regarding the safety and efficacy of probiotics in the prevention of ventilator-associated pneumonia (VAP).

DATA SOURCES

PubMed databases (January 2000-August 2011) were searched and a bibliographic review of published articles was performed to identify original reports of probiotic administration for the prevention of VAP using the search terms probiotics, synbiotics, and ventilator-associated pneumonia.

STUDY SELECTION AND DATA EXTRACTION

Two pilot studies, 2 randomized controlled trials (RCTs), and 1 meta-analysis have addressed probiotic use for VAP prevention and were included in the review.

DATA SYNTHESIS

VAP frequently occurs in mechanically ventilated patients. Given the lack of new antimicrobial agents, probiotics have been studied for their ability to modify human microflora colonization. Two studies examining pathogen colonization rates favored probiotics, with reduced incidence and increased duration until the emergence of new species. One prospective RCT found significant reduction in the incidence of VAP and colonization rates, but no significant difference in patient disposition outcomes. Another RCT examining 28-day mortality found no overall benefit with probiotic use and no reduction in colonization rates.

CONCLUSIONS

Clinical trials have failed to demonstrate a consistent beneficial effect of probiotics in mechanically ventilated patients; thus, they are not recommended for routine clinical use. However, heterogeneity among study designs may hinder this assessment and the designs should be unified in future research.

Ventilator-associated pneumonia: update on etiology, prevention, and management

Ventilator-associated pneumonia (VAP) remains one of the most important nosocomial infections in the intensive care unit and has been the focus of much recent research. New evidence on VAP preventive measures includes evidence for the efficacy of changes in endotracheal tube cuff design and materials, drainage of subglottic secretions, saline instillation prior to tracheal suctioning, patient positioning, oral decontamination, aerosolized antibiotics, and probiotic use. In the absence of a clinical reference standard, the diagnosis of VAP remains problematic. Although extensive research on invasive sampling techniques for microbiological confirmation has been conducted, current evidence suggests that endotracheal aspirates are equivalent. Promising new diagnostic methods include non-culture-based microbiological techniques and biomarkers. The treatment of VAP continues to evolve. Shorter antibiotic treatment duration is effective. As well, novel methods of antimicrobial delivery to maximize antibiotic effectiveness and the use of inflammatory biomarkers to guide duration of antibiotic therapy show promise.

The diagnostic dilemma of ventilator-associated pneumonia in critically ill children

OBJECTIVE

A review of the existing literature on ventilator-associated pneumonia in children with emphasis on problems in diagnosis.

DATA SOURCES

A systematic literature review from 1947 to 2010 using Ovid MEDLINE, PubMed, Cochrane Central Register of Controlled Trials, and ISI Web of Science using key words "ventilator associated pneumonia" and "children." Where pediatric data were lacking, appropriate adult studies were reviewed and similarly referenced.

STUDY SELECTION

Two hundred sixty-two pediatric articles were reviewed and data from 48 studies selected. Data from 61 adult articles were also included in this review.

DATA EXTRACTION AND SYNTHESIS

Ventilator-associated pneumonia is the second most common nosocomial infection and the most common reason for antibiotic use in the pediatric intensive care unit. Attributable mortality is uncertain but ventilator-associated pneumonia is associated with significant morbidity and cost. Diagnosis is problematic in that clinical, radiologic, and microbiologic criteria lack sensitivity and specificity relative to autopsy histopathology and culture. Qualitative tracheal aspirate cultures are commonly used in diagnosis but lack specificity. Quantitative tracheal aspirate cultures have sensitivity (31-69%) and specificity (55-100%) comparable to bronchoalveolar lavage (11-90% and 43-100%, respectively) but concordance for the same bacterial species when compared with autopsy lung culture was better for bronchoalveolar lavage (52-90% vs. 50-76% for quantitative tracheal aspirate). Staphylococcus aureus and Pseudomonas species are the most common organisms, but microbiologic flora change over time and with antibiotic use. Initial antibiotics should offer broad-spectrum coverage but should be narrowed as clinical response and cultures dictate.

CONCLUSIONS

Ventilator-associated pneumonia is an important nosocomial infection in the pediatric intensive care unit. Conclusions regarding epidemiology, treatment, and outcomes are greatly hampered by the inadequacies of current diagnostic methods. We recommend a more rigorous approach to diagnosis by using the Centers for Disease Control and Prevention algorithm. Given that ventilator-associated pneumonia is the most common reason for antibiotic use in the pediatric intensive care unit, more systematic studies are sorely needed.

Antibiotics or probiotics as preventive measures against ventilator-associated pneumonia: a literature review

Introduction

Mechanically ventilated critically ill patients frequently develop ventilator-associated pneumonia (VAP), a life-threatening complication. Proposed preventive measures against VAP include, but are not restricted to, selective decontamination of the digestive tract (SDD), selective oropharyngeal decontamination (SOD) and the use of probiotics. Probiotics are live bacteria that could have beneficial effects on the host by altering gastrointestinal flora. Similar to SDD and SOD, a prescription of probiotics aims at the prevention of secondary colonization of the upper and/or lower digestive tract.

Methods

We performed a literature review to describe the differences and similarities between SDD/SOD and probiotic preventive strategies, focusing on (a) efficacy, (b) risks, and (c) the routing of these strategies.

Results

Reductions in the incidence of VAP have been achieved with SDD and SOD. Two large randomized controlled trials even showed reduced mortality with these preventive strategies. Randomized controlled trials of probiotic strategies also showed a reduction of the incidence of VAP, but trials were too small to draw firm conclusions. Preventive strategies with antibiotics and probiotics may be limited due to the risk of emerging resistance to the locally applied antibiotics and the risk of probiotic-related infections, respectively. The majority of trials of SDD and SOD did not exhaustively address the issue of emerging resistance. Likewise, trials of probiotic strategies did not adequately address the risk of colonization with probiotics and probiotic-related infection. In studies of SDD and SOD the preventive strategy aimed at decontamination of the oral cavity, throat, stomach and intestines, and the oral cavity and throat, respectively. In the vast majority of studies of probiotic therapy the preventive strategy aimed at decontamination of the stomach and intestines.

Conclusions

Prophylactic use of antibiotics in critically ill patients is effective in reducing the incidence of VAP. Probiotic strategies deserve consideration in future well-powered trials. Future studies are needed to determine if preventive antibiotic and probiotic strategies are safe with regard to development of antibiotic resistance and probiotic infections. It should be determined whether the efficacy of probiotics improves when these agents are provided to the mouth and the intestines simultaneously.

Diagnosis, management and prevention of ventilator-associated pneumonia: an update

Ventilator-associated pneumonia (VAP) affects 10-20% of mechanically ventilated patients and is associated with increased morbidity and mortality and high costs. Early diagnosis is crucial for rapid appropriate antimicrobial therapy to be instituted, but debate remains as to the optimal diagnostic strategy. Noninvasive clinical-based diagnosis is rapid but may not be as accurate as invasive techniques. Increased use of biomarkers and advances in genomics and proteomics may help speed up diagnosis. Management of VAP relies principally on appropriate antimicrobial therapy, which should be selected according to individual patient factors, such as previous antibacterial therapy and length of hospitalization or mechanical ventilation, and local infection and resistance patterns. In addition, once bacterial culture and sensitivity results are available, broad-spectrum therapy should be de-escalated to provide a more specific, narrower-spectrum cover. Optimum duration of antibacterial therapy is difficult to define and should be tailored to clinical response. Biomarker levels may be useful to monitor response to therapy. With the high morbidity and mortality, prevention of VAP is important and several strategies have been shown to reduce the rates of VAP in mechanically ventilated patients, including using noninvasive ventilation where possible, and semi-recumbent positioning. Other potentially beneficial preventive techniques include subglottal suctioning, oral decontamination strategies and antimicrobial-coated endotracheal tubes, although further study is needed to confirm the cost effectiveness of these strategies.

Efficacy of a synbiotic supplementation in the prevention of common winter diseases in children: a randomized, double-blind, placebo-controlled pilot study

Background and aims: The purpose of this study was to investigate the efficacy of a synbiotic supplementation in reducing common winter diseases in children.

Methods: A randomized, double-blind, placebo-controlled, multicentre study was conducted in young school-age children (3—7 years old) during a winter period. Participants were otherwise healthy children who suffered from at least three episodes of ear, nose and throat (ENT), respiratory tract or gastrointestinal illness during the previous winter. They were supplemented daily with either a synbiotic preparation (Lactobacillus helveticus R0052, Bifidobacterium infantis R0033, Bifidobacterium bifidum R0071, and fructooligosaccharide) or a matched placebo for 3 months. Over this period, all emergent health episodes of any type were recorded by parents in a diary. They were checked by investigators at regular monthly visits. The main study outcome was the percentage of children free of any episode during the study course.

Results: We randomized 135 children (mean age: 4.1±1.0 years) to the synbiotic group ( n = 62) or placebo ( n = 73) group. At least one illness episode was reported in 32 children in the synbiotic group and 50 in the placebo group (51.6% versus 68.5%). This corresponded to a significant 25% relative risk reduction (95% CI 0.6—44.3%; p = 0.045). This difference was due to a decrease in the number of children who suffered from at least one ENT, respiratory tract or gastrointestinal disorder (50.0% with synbiotic versus 67.1% with placebo; p = 0.044). At least one sickness school day loss was noted in 25.8% of children with the synbiotic as compared with 42.5% with placebo ( p = 0.043). No treatment related side effects were detected in either group.

Conclusions: This study suggests that a 3-month supplementation with this synbiotic preparation can decrease the risk of occurrence of common infectious diseases in children and limits the risk of school day loss.

Probiotics in the critically ill patient: a double blind, randomized, placebo-controlled trial

PURPOSE

Probiotics have been shown to be able to restore a non-pathogenic digestive flora, to prevent digestive colonization by pathogenic bacteria, and to modulate immunity. The aim of this study was to assess the effects of prophylactic probiotic administration in patients ventilated for up to 2 days.

METHODS

This study was performed as a double-blind, concealed randomized, placebo-controlled trial in a French medical intensive care unit (ICU). Adult patients mechanically ventilated for a period of more than 48 h received enterally administered probiotics (Ergyphilus, 2 x 10(10) lactic acid bacteria, mostly Lactobacillus rhamnosus GG, once a day) or placebo until successful weaning.

RESULTS

A total of 167 patients were included. The two groups were comparable at baseline. The 28-day mortality rates were not different in the probiotic (25.3%) and placebo groups (23.7%). Mortality rates in ICU and at 90 days were also unaffected by the treatment. The incidence of ICU-acquired infections did not differ significantly except for that of catheter-related bloodstream infections that was lowered by probiotics. On a prespecified subgroup analysis, we found a reduction of the 28-day mortality among severe sepsis patients (total n = 101) treated with probiotics (n = 52) with an odds ratio (OR) for death at 0.38 (95% CI 0.16-0.93, p = 0.035). By contrast, probiotics were associated with a higher mortality rate in non-severe sepsis patients (OR 3.09, 95% CI 0.87-11.01, p = 0.08).

CONCLUSIONS

Although numerous uncertainties remain (type and the number of strains to use, delay and length of administration), and despite an acceptable safety profile, the daily prophylactic administration of probiotics cannot be encouraged in the critically ill patient.

Probiotic prophylaxis of ventilator-associated pneumonia: a blinded, randomized, controlled trial

RATIONALE

Enteral administration of probiotics may modify the gastrointestinal environment in a manner that preferentially favors the growth of minimally virulent species. It is unknown whether probiotic modification of the upper aerodigestive flora can reduce nosocomial infections.

OBJECTIVES

To determine whether oropharyngeal and gastric administration of Lactobacillus rhamnosus GG can reduce the incidence of ventilator-associated pneumonia (VAP).

METHODS

We performed a prospective, randomized, double-blind, placebo-controlled trial of 146 mechanically ventilated patients at high risk of developing VAP. Patients were randomly assigned to receive enteral probiotics (n = 68) or an inert inulin-based placebo (n = 70) twice a day in addition to routine care.

MEASUREMENTS AND MAIN RESULTS

Patients treated with Lactobacillus were significantly less likely to develop microbiologically confirmed VAP compared with patients treated with placebo (40.0 vs. 19.1%; P = 0.007). Although patients treated with probiotics had significantly less Clostridium difficile-associated diarrhea than patients treated with placebo (18.6 vs. 5.8%; P = 0.02), the duration of diarrhea per episode was not different between groups (13.2 ± 7.4 vs. 9.8 ± 4.9 d; P = 0.39). Patients treated with probiotics had fewer days of antibiotics prescribed for VAP (8.6 ± 10.3 vs. 5.6 ± 7.8 d; P = 0.05) and for C. difficile-associated diarrhea (2.1 ± 4.8 SD d vs. 0.5 ± 2.3 d; P = 0.02). No adverse events related to probiotic administration were identified.

CONCLUSIONS

These pilot data suggest that L. rhamnosus GG is safe and efficacious in preventing VAP in a select, high-risk ICU population. Clinical trial registered with www.clinicaltrials.gov (NCT00613795).