Total artificial nutrition is associated with major changes in the fecal flora

Activation of Immune and Antiviral Effects by Euglena Extracts: A Review

Influenza is an acute respiratory illness caused by influenza virus infection, which is managed using vaccines and antiviral drugs. Recently, the antiviral effects of plants and foods have gained attention. Euglena is a motile unicellular alga and eukaryotic photosynthetic microorganism. It has secondary chloroplasts and is a mixotroph able to feed by photosynthesis or phagocytosis. This review summarizes the influenza treatment effects of Euglena from the perspective of a functional food that is attracting attention. While it has been reported that Euglena contributes to suppressing blood sugar levels and ameliorates symptoms caused by stress by acting on the autonomic nervous system, the immunostimulatory and antiviral activities of Euglena have also been reported. In this review, I focused on the immunostimulation of antiviral activity via the intestinal environment and the suppression of viral replication in infected cells. The functions of specific components of Euglena, which also serves as the source of a wide range of nutrients such as vitamins, minerals, amino acids, unsaturated fatty acids, and β-1,3-glucan (paramylon), are also reviewed. Euglena has animal and plant properties and natural compounds with a wide range of functions, providing crucial information for improved antiviral strategies.

Gut microbiome alterations in ICU patients with enteral nutrition-related diarrhea

Enteral Nutrition-related Diarrhea (END) is an extremely common complication in Intensive Care Unit (ICU) patients. However, it is currently unclear whether the patient’s gut microbiota is disturbed. Our study aimed to explore the characteristics of gut microbiota changes in END patients. We divided ICU patients into no-END group (n = 7) and END group (n = 7) according to whether they had END, then stool samples were collected separately. The V3-V4 region of stool bacterial 16S rRNA gene was amplified by PCR and sequenced on an Illumina MiSeq PE300 platform. Microbiome data obtained by quality control were analyzed, including microbial community composition, diversity and gene function prediction.The results showed that the dominant gut microbiota in ICU patients who were given total enteral nutrition were Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, and Verrucomicrobia. Bacterial richness and diversity in END patients were all significantly lower than those in no-END patients. In addition, END caused significant changes in bacterial composition. LEfSe found 34 biomarkers represented by Bacteroidetes and Subdoligranulum in the no-END group as well as 11 biomarkers represented by Enterococcus and Klebsiella in the END group. Finally, through PICRUST function prediction, we found that diarrhea led to abnormal changes in numerous KEGG pathways mainly related to immunity and metabolism. In short, ICU patients with END have severe gut dysbiosis, and our study provides a reliable experimental basis for the patient’s microbiota therapy.

The Effects of Enteral Nutrition on the Intestinal Environment in Patients in a Persistent Vegetative State

Enteral nutrition (EN) is a rational approach to providing nutritional intake via the intestines in patients who are unable to tolerate parenteral nutrition. We conducted a preliminary study to investigate the effects of EN on the intestinal environment in 10 patients in a persistent vegetative state (PVS) (n = 5 each in the EN and EN with probiotics; Clostridium butyricum MIYAIRI 588) groups compared with 10 healthy controls. The results of 16S amplicon sequencing of the intestinal microbiota showed that EN led to dysbiosis with a decrease in α-diversity and an obvious change in β-diversity. A particularly significant decrease was seen in useful intestinal bacteria such as Bifidobacterium and butyrate-producing bacteria. Analysis of intestinal metabolites also supported these results, showing significant decreases in butyric and pyruvic acid after EN. Although C. butyricumMIYAIRI 588 improved some intestinal metabolites that were decreased after EN, it did not improve the dysbiosis of the intestinal microbiota. These findings indicate that EN causes dysbiosis of the intestinal microbiota and an imbalance in some intestinal metabolites in patients in a PVS. Moreover, although C. butyricumMIYAIRI 588 improved the imbalance of some intestinal metabolites after EN, it did not prevent dysbiosis of the intestinal microbiota.

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.

Fiber in the ICU: Should it Be a Regular Part of Feeding?

PURPOSE OF REVIEW

To highlight the controversy of fiber use in the current critical care nutrition guidelines; review the effect of fiber on the gut microbiota in the critically ill; and examine the data on fiber and outcomes in the intensive care setting.

RECENT FINDINGS

Fiber is increasingly recognized as a necessary component of colonic health and nutrition support. In critical illness there is a shift toward gut dysbiosis and immune dysregulation. Through fermentation and the generation of short-chain fatty acids, fiber has a role in maintaining intestinal homeostasis, immune function, and supporting commensal bacteria. In contrast to fermentable fiber, recent animal models suggest that non-fermentable fiber can also favorably alter intestinal homeostasis in a mechanism distinct from short chain fatty acids. In the critically ill, RCTs and meta-analyses suggest that soluble and mixed fiber supplemented enteral nutrition can reduce diarrhea and is well tolerated. Based on limited data, there may be benefits in reducing length of hospital stay, certain infections, and glucose metabolism. Nonetheless, the role of fiber enriched nutrition in critically ill patients is controversial as evident in the conflicting guidelines. Despite shortcomings in the literature, soluble and mixed fiber supplemented enteral nutrition is safe and beneficial in most hemodynamically stable intensive care patients. More research is necessary to determine optimal fiber composition.

Effects of a Synbiotic Formula on Functional Bowel Disorders and Gut Microbiota Profile during Long-Term Home Enteral Nutrition (LTHEN): A Pilot Study

Long-term enteral nutrition (LTEN) can induce gut microbiota (GM) dysbiosis and gastrointestinal related symptoms, such as constipation or diarrhoea. To date, the treatment of constipation is based on the use of laxatives and prebiotics. Only recently have probiotics and synbiotics been considered, the latter modulating the GM and regulating intestinal functions. This randomized open-label intervention study evaluated the effects of synbiotic treatment on the GM profile, its functional activity and on intestinal functions in long-term home EN (LTHEN) patients. Twenty LTHEN patients were recruited to take enteral formula plus one sachet/day of synbiotic (intervention group, IG) or enteral formula (control group, CG) for four months and evaluated for constipation, stool consistency, and GM and metabolite profiles. In IG patients, statistically significant reduction of constipation and increase of stool consistency were observed after four months (T₁), compared to CG subjects. GM ecology analyses revealed a decrease in the microbial diversity of both IC and CG groups. Biodiversity increased at T₁ for 5/11 IG patients and Methanobrevibacter was identified as the biomarker correlated to the richness increase. Moreover, the increase of short chain fatty acids and the reduction of harmful molecules have been correlated to synbiotic administration. Synbiotics improve constipation symptoms and influences Methanobrevibacter growth in LTHEN patients.

Gut microbiota profiles of treatment-naïve adult acute myeloid leukemia patients with neutropenic fever during intensive chemotherapy

The intestinal bacterial flora of febrile neutropenic patients has been found to be significantly diverse. However, there are few reports of alterations of in adult acute myeloid leukemia (AML) patients. Stool samples of each treatment-naïve AML patient were collected the day before initiation of induction chemotherapy (pretreatment), on the first date of neutropenic fever and first date of bone marrow recovery. Bacterial DNA was extracted from stool samples and bacterial 16s ribosomal RNA genes were sequenced by next-generation sequencing. Relative abundance, overall richness, Shannon's diversity index and Simpson's diversity index were calculated. No antimicrobial prophylaxis was in placed in all participants. Ten cases of AML patients (4 male and 6 female) were included with a median age of 39 years (range: 19–49) and all of patients developed febrile neutropenia. Firmicutes dominated during the period of neutropenic fever, subsequently declining after bone marrow recovery a pattern in contrast to that shown by Bacteroidetes and Proteobacteria. Enterococcus was more abundant in the febrile neutropenia period compared to pretreatment (mean difference +20.2; p < 0.0001) while Escherichia notably declined during the same period (mean difference -11.2; p = 0.0064). At the operational taxonomic unit (OTU) level, there was a significantly higher level of overall richness in the pretreatment period than in the febrile neutropenic episode (mean OTU of 203.1 vs. 131.7; p = 0.012). Both of the diversity indexes of Shannon and Simpson showed a significant decrease during the febrile neutropenic period. Adult AML patients with a first episode of febrile neutropenia after initial intensive chemotherapy demonstrated a significant decrease in gut microbiota diversity and the level of diversity remained constant despite recovery of bone marrow.

Nutrition Support and the Gastrointestinal Microbiota: A Systematic Review

BACKGROUND

Low microbial diversity or altered microbiota composition is associated with many disease states. In the treatment of many conditions, enteral (EN) or parenteral (PN) nutrition is frequently required.

OBJECTIVE

This systematic review aimed to identify and evaluate the evidence of the effect of EN vs PN on the gastrointestinal microbiota.

METHOD

A comprehensive systematic literature search of 5 databases was completed to review studies published until February 2020. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were utilized in completion of the review with the Academy of Nutrition and Dietetics quality criteria checklist and Grading of Recommendations Assessment, Development and Evaluation to evaluate the included studies. The review was registered on PROSPERO (CRD42018091328). Studies were eligible for inclusion if participants were older than 3 years, patients received either EN, PN or both, with some patients receiving each mode of nutrition support. The main outcome was any assessment of the gastrointestinal microbiota, including diversity or taxa abundance.

RESULTS

Eleven articles (n = 367 patients) met the inclusion criteria and were evaluated. Seven studies (n = 237) reported greater abundance of Proteobacteria with the provision of PN compared to EN; 6 studies (n = 172) reported lower Firmicutes and 5 studies (n = 155) lower Bacteroidetes. In 7 studies (n = 282), microbial diversity was lower with provision of PN than EN. The Grading of Recommendations Assessment, Development and Evaluation certainty of evidence was very low.

CONCLUSIONS

Provision of PN may lead to greater abundance of Proteobacteria and reduced microbial diversity; however, there is limited literature on this topic and additional research is warranted to improve understanding of the impact of EN vs PN on the microbiota.

Pilot study investigating the effect of enteral and parenteral nutrition on the gastrointestinal microbiome post-allogeneic transplantation

Nutrition support is frequently required post-allogeneic haematopoietic progenitor cell transplantation (HPCT); however, the impact of mode of feeding on the gastrointestinal microbiome has not been explored. This study aimed to determine if there is a difference in the microbiome between patients receiving enteral nutrition (EN) and parenteral nutrition (PN) post-allogeneic HPCT. Twenty-three patients received either early EN or PN when required. Stool samples were collected at 30 days post-transplant and analysed with shotgun metagenomic sequencing. There was no difference in microbial diversity between patients who received predominantly EN (n = 13) vs. PN (n = 10) however patients who received predominantly EN had greater abundance of Faecalibacterium (P < 0·001) and ruminococcus E bromii (P = 0·026). Patients who had minimal oral intake for a longer duration during provision of nutrition support had a different overall microbial profile (P = 0·044), lower microbial diversity (P = 0·004) and lower abundance of faecalibacterium prausnitzii_C (P = 0·030) and Blautia (P = 0·007) compared to patients with greater oral intake. Lower microbial diversity was found in patients who received additional beta lactam antibiotics (P = 0·042) or had a longer length of hospital stay (P = 0·019). Post-HPCT oral intake should be encouraged to maintain microbiota diversity and, if nutrition support is required, EN may promote a more optimal microbiota profile.

Effect of Honey on Diarrhea and Fecal Microbiotain in Critically Ill Tube-Fed Patients: A Single Center Randomized Controlled Study

Background

In patients admitted to the Intensive Care Unit (ICU), Enteral Nutrition (EN) is the first choice for feeding support, however, it is often complicated by gastrointestinal side effects, such as diarrhea. There are no studies that have specifically evaluated effect of a prebiotic, which prevents diarrhea during enteral nutrition.

Objective

This study aimed at evaluating the effect of honey in enteral diet during occurrence of diarrhea and fecal microbiotain in critically ill patients.

Materials and Methods

In this double-blind, randomized controlled single-center study, 32 patients were randomly selected to receive a high protein kitchen enteral diet and the study group had honey as 10% of its carbohydrate intake. Quantitative analyses of bifidobacterium and Lactobacillus species of fecal samples were assessed by Real-Time Polymerase Chain Reaction (PCR) on days 0 and 7.

Results

Patients in the honey group showed an insignificant increase in the frequency of bifidobacterium DNA by study day 7 in comparison with the control group. In the honey group, there was a considerable reduction in diarrhea (P = 0.09). A significant difference was found in length of Intensive Care Unit (ICU) stay (P = 0.001) and Sequential Organ Failure Assessment (SOFA) score (P = 0.04) in favor of the honey group.

Conclusions

Enteral nutrition with honey might reduce the length of stay at the ICU and development of organ failure in critically ill patients. It seems that honey helps reduce the incidence of diarrhea.

Diarrhea in Critically Ill Patients: The Role of Enteral Feeding

This tutorial presents a systematic approach to the management of diarrhea in the critical care setting. Diarrhea is a common and prevalent problem in critically ill patients. Despite the high prevalence, its management is far from simple. Professionals are confronted with a myriad of definitions based on frequency, consistency, and volume. The causes are complex and multifactorial, yet enteral tube feeding formula is believed to be the perpetrator. Potential causes for diarrhea are discussed, and 3 case reports provide context to examine the treatment from a nutrition perspective. Each scenario is comprehensively addressed discussing potential causes and providing specific clinical strategies contributing to improved bowel function in this patient group. The approach used for diarrhea management is based on a complete understanding of enteral tube formula, their composition, and their impact in the presence of gut dysfunction. Choosing the right feeding formula may positively influence bowel function and contribute to improved nutrition.

Metagenomic Analysis Reveals Dynamic Changes of Whole Gut Microbiota in the Acute Phase of Intensive Care Unit Patients

BACKGROUND

Metagenomic analysis targeting the 16S rRNA gene has made it possible to characterize the vast array of microorganisms contained in the gut.

AIM

The purpose of this study was to evaluate how gut microbiota change in intensive care unit (ICU) patients in the acute phase after admission.

METHODS

This prospective observational cohort study investigated 12 patients admitted to a single ICU of a large urban tertiary referral hospital. All patients were mechanically ventilated on admission. Fecal samples were collected from patients on days 1-2, 2-4, 5-8, and 7-10 after admission. DNA was extracted from fecal samples, and 16S rRNA deep sequencing was performed to monitor gut changes.

RESULTS

Bacteria belonging to the phyla Firmicutes or Bacteroidetes were predominant in each sample. We observed serial dynamic changes in the percentages of Bacteroidetes and Firmicutes that were significantly altered during study period (p < 0.05). A ratio of Bacteroidetes to Firmicutes (B/F ratio) of >10 was seen in four of the six patients who died, whereas a B/F ratio of <0.10 was seen in only one of the six deaths. None of the survivors had a B/F ratio of >10 or <0.10. There was a statistical difference in the B/F ratio between the dead patients and survivors (p = 0.022).

CONCLUSIONS

Dynamic changes in gut microbiota at the phylum level of ICU patients during the acute phase were identified by high-throughput DNA sequencing. An extreme imbalance in gut microbiota may be associated with prognosis in critically ill patients.

The microbiome and critical illness

The central role of the microbiome in critical illness is supported by a half century of experimental and clinical study. The physiological effects of critical illness and the clinical interventions of intensive care substantially alter the microbiome. In turn, the microbiome predicts patients' susceptibility to disease, and manipulation of the microbiome has prevented or modulated critical illness in animal models and clinical trials. This Review surveys the microbial ecology of critically ill patients, presents the facts and unanswered questions surrounding gut-derived sepsis, and explores the radically altered ecosystem of the injured alveolus. The revolution in culture-independent microbiology has provided the tools needed to target the microbiome rationally for the prevention and treatment of critical illness, holding great promise to improve the acute and chronic outcomes of the critically ill.

Saccharomyces boulardii CNCM I-745 supports regeneration of the intestinal microbiota after diarrheic dysbiosis - a review

The probiotic medicinal yeast Saccharomyces cerevisiae HANSEN CBS 5926 (Saccharomyces boulardii CNCM I-745) is used for the prevention and treatment of diarrhea. Its action is based on multiple mechanisms, including immunological effects, pathogen-binding and antitoxinic effects, as well as effects on digestive enzymes. Correlated with these effects, but also due to its inherent properties, S. boulardii is able to create a favorable growth environment for the beneficial intestinal microbiota, while constituting extra protection to the host mucus layer and mucosa. This review focuses on the positive influence of S. boulardii on the composition of the intestinal microbiota. In a dysbiosis, as during diarrhea, the main microbial population (especially Lachnospiraceae, Ruminococcaceae, Bacteroidaceae, and Prevotellaceae) is known to collapse by at least one order of magnitude. This gap generally leads to transient increases in pioneer-type bacteria (Enterobacteriaceae, Bifidobacteriaceae, and Clostridiaceae). Several human studies as well as animal models demonstrate that treatment with S. boulardii in dysbiosis leads to the faster reestablishment of a healthy microbiome. The most relevant effects of S. boulardii on the fecal composition include an increase of short chain fatty acid-producing bacteria (along with a rise in short chain fatty acids), especially of Lachnospiraceae and Ruminococcaceae, as well as an increase in Bacteroidaceae and Prevotellaceae. At the same time, there is a suppression of pioneer bacteria. The previously observed preventive action of S. boulardii, eg, during antibiotic therapy or regarding traveler’s diarrhea, can be explained by several mechanisms, including a stabilizing effect on the healthy microbiota as well as possibly on the mucus layer. Several different dysbiotic situations could profit from the effects of S. boulardii CNCM I-745. Its additional potential lies in a general stabilization of the gut flora for at-risk populations. More studies are needed to explore the full potential of this versatile probiotic yeast.

Blood Groups in Infection and Host Susceptibility

Blood group antigens represent polymorphic traits inherited among individuals and populations. At present, there are 34 recognized human blood groups and hundreds of individual blood group antigens and alleles. Differences in blood group antigen expression can increase or decrease host susceptibility to many infections. Blood groups can play a direct role in infection by serving as receptors and/or coreceptors for microorganisms, parasites, and viruses. In addition, many blood group antigens facilitate intracellular uptake, signal transduction, or adhesion through the organization of membrane microdomains. Several blood groups can modify the innate immune response to infection. Several distinct phenotypes associated with increased host resistance to malaria are overrepresented in populations living in areas where malaria is endemic, as a result of evolutionary pressures. Microorganisms can also stimulate antibodies against blood group antigens, including ABO, T, and Kell. Finally, there is a symbiotic relationship between blood group expression and maturation of the gastrointestinal microbiome.

Could enteral nutrition improve the outcome of patients with haematological malignancies undergoing allogeneic haematopoietic stem cell transplantation? A study protocol for a randomized controlled trial (the NEPHA study)

BACKGROUND

Myeloablative allogeneic haematopoietic stem cell transplantation (allo-HSCT) is a major procedure usually accompanied by multifactorial malnutrition, prompting the recommendation of systematic artificial nutritional support. Parenteral nutrition (PN) is usually administered during allo-HSCT, essentially for practical reasons. Recently published data suggest that enteral nutrition (EN), given as systematic artificial nutrition support, could decrease grade III-IV graft-versus-host disease (GVHD) and infectious events, which are associated with early toxicity after allo-HSCT and then have an impact on early transplant-related mortality (D100 mortality).

METHODS/DESIGN

We report on the NEPHA trial: an open-label, prospective, randomised, multi-centre study on two parallel groups, which has been designed to evaluate the effect of EN compared to PN on early toxicity after an allo-HSCT procedure. Two hundred forty patients treated with allo-HSCT for a haematological malignancy will be randomly assigned to two groups to receive either EN or PN. The primary endpoint will assess the effect of EN on D100 mortality. Secondary endpoints will compare EN and PN with regards to the main haematological, infectious and nutritional outcomes.

DISCUSSION

The impacts of nutritional support should exceed the limits of nutritional status improvement: EN may directly reduce immunological and infectious events, as well as decrease early transplant-related morbidity and mortality. EN and PN need to be prospectively compared in order to assess their impacts and to provide treatment guidelines. (Clinical trials gov number: NCT01955772; registration: July 19th, 2013).

16S rRNA gene pyrosequencing reveals shift in patient faecal microbiota during high-dose chemotherapy as conditioning regimen for bone marrow transplantation

Gastrointestinal disturbances are a side-effect frequently associated with haematological malignancies due to the intensive cytotoxic treatment given in connection with bone marrow transplantation (BMT). However, intestinal microbiota changes during chemotherapy remain poorly described, probably due to the use of culture-based and low-resolution molecular methods in previous studies. The objective of our study was to apply a next generation DNA sequencing technology to analyse chemotherapy-induced changes in faecal microbiota. We included eight patients with non-Hodgkin's lymphoma undergoing one course of BMT conditioning chemotherapy. We collected a prechemotherapy faecal sample, the day before chemotherapy was initiated, and a postchemotherapy sample, collected 1 week after the initiation of chemotherapy. Total DNA was extracted from faecal samples, denaturing high-performance liquid chromatography based on amplification of the V6 to V8 region of the 16S ribosomal RNA (rRNA) gene, and 454-pyrosequencing of the 16 S rRNA gene, using PCR primers targeting the V5 and V6 hypervariable 16S rRNA gene regions were performed. Raw sequence data were screened, trimmed, and filtered using the QIIME pipeline. We observed a steep reduction in alpha diversity and significant differences in the composition of the intestinal microbiota in response to chemotherapy. Chemotherapy was associated with a drastic drop in Faecalibacterium and accompanied by an increase of Escherichia. The chemotherapy-induced shift in the intestinal microbiota could induce severe side effects in immunocompromised cancer patients. Our study is a first step in identifying patients at risk for gastrointestinal disturbances and to promote strategies to prevent this drastic shift in intestinal microbiota.

Parenteral nutrition increases susceptibility of ileum to invasion by E coli

BACKGROUND

Parenteral nutrition (PN), with the lack of enteral feeding, compromises mucosal immune function and increases the risk of infections. We developed an ex vivo intestinal segment culture (EVISC) model to study the ex vivo effects of PN on susceptibility of the ileum to invasion by extra-intestinal pathogenic Escherichia coli (ExPEC) and on ileal secretion of antimicrobial secretory phospholipase A2 (sPLA2) in response to the pathogen.

MATERIALS AND METHODS

Study 1: Using mouse (n = 7) ileal tissue, we examined the effects of ileal region (proximal versus distal) and varying ExPEC inoculum concentrations on ex vivo susceptibility to ExPEC invasion and sPLA2 secretion. Study 2: Ten mice were randomized to oral chow or intravenous PN feeding for 5 d (n = 5/group). Using the EVISC model, we compared the susceptibility of ileal tissue to invasion by ExPEC and sPLA2 secretion in response to the pathogen.

RESULTS

Study 1: The proximal ileum was more susceptible to invasion (P < 0.0001) and secreted lower amounts of sPLA2 (P = 0.0002) than the distal ileum. Study 2: Ileal tissue from PN-fed animals was more susceptible (approximately 4-fold, P = 0.018) to invasion than those from chow-fed animals. Ileal tissue from PN-fed animals secreted less sPLA2 (P < 0.02) than those from chow-fed animals.

CONCLUSIONS

The data illustrate EVISC as a reproducible model for studying host-pathogen interactions and the effects of diet on susceptibility to infections. Specifically, the findings support our hypothesis that PN with the lack of enteral feeding decreases mucosal responsiveness to pathogen exposure and provides a plausible mechanism by which PN is associated with increased risk of infectious complication.

Effects of perioperative synbiotic treatment on infectious complications, intestinal integrity, and fecal flora and organic acids in hepatic surgery with or without cirrhosis

BACKGROUND

The aim of this study was to assess the effect of preoperative and postoperative synbiotic treatment in hepatectomy patients with or without liver cirrhosis.

METHODS

Sixty-one patients with hepatic cancer were assigned randomly to receive either oral synbiotics that consisted of Bifidobacterium, Lactobacillus, and galactooligosaccharides or no synbiotics (control) preoperatively for 14 days and postoperatively for 11 days. Infectious complications, intestinal mucosal integrity as measured by serum diamine oxidase (DAO) activity, and fecal flora and organic acid concentrations were compared between synbiotic treatment (n = 32) and control (n = 29) groups.

RESULTS

Fecal flora culture and organic acid concentrations were changed after hepatectomy in both groups. The postsurgery decrease in DAO activity was less profound in the synbiotic-treated group (P < .01) and was correlated negatively with serum interleukin 6 and C-reactive protein concentrations (P < .001). Infectious complications occurred in 5 (17.2%) patients in the control group and no patients in the synbiotic-treated group (P < .05).

CONCLUSION

Perioperative synbiotic treatment attenuated the decrease in intestinal integrity and reduced the rate of infectious complications in patients with or without liver cirrhosis who underwent hepatic surgery.

Mechanisms, prevention, and management of diarrhea in enteral nutrition

PURPOSE OF REVIEW

Diarrhea is a common and problematic complication of enteral nutrition, about which there has been considerable recent research. This article briefly reviews the mechanisms of diarrhea during enteral nutrition and then critically appraises the recent and emerging evidence for the prevention and management of this distressing complication.

RECENT FINDINGS

For many years, fiber was extensively investigated for its role in preventing diarrhea; however, a more recent focus has been the investigation of specific fiber blends, including soluble fibers and prebiotics, for which there is now considerable quality evidence. Enteral nutrition may result in deleterious effects on the gastrointestinal microbiota, including reductions in bifidobacteria and key butyrate producers. Their modulation by prebiotics has been confirmed in studies on healthy individuals, but convincing evidence in acutely ill patients is required. Probiotics have undergone extensive recent research and their effect on preventing diarrhea in enteral nutrition would seemingly be strain dependent. Further research is required on systematic approaches to treating diarrhea during enteral nutrition.

SUMMARY

A number of factors contribute to the pathogenesis of diarrhea in enteral nutrition, meaning that approaches to its prevention and management are necessarily multifaceted. Approaches to prevent diarrhea during enteral nutrition, and a clinical algorithm to manage it, are now presented.

[Microbiota and enteral nutrition]

Enteral nutrition is a nutritional therapy that is used in up to 10% of hospitalized patients. It involves a dramatic change in the provision of nutrients to the intestine and this, along with metabolic stress and drugs used, is responsible for a marked dysbiosis. Even though there is a huge level of between-subject variability, this dysbiosis is characterized by a decrease in the dominant flora, an increase in potentially pathogenic microorganisms and a reduction in the number of individual strains. The main characteristic of these changes in the microbiota is diarrhea, which has many consequences in these patients. Saccharomyces boulardii is able to prevent enteral nutrition-associated diarrhea, probably through an increase in short-chain fatty acid production. Alongside its role in the onset and prevention of diarrhea, the microbiota may be involved in energy harvesting and changes in the nutritional status. Manipulations of the microbiota may therefore be a novel way to increase feeding efficiency in tube-fed patients.

Nutritional consequences and nutrition therapy in Crohn's disease

75% of hospital patients with Crohn's disease (CD) suffer from malnutrition and one third of CD patients have a body mass index below 20. Inflammatory bowel diseases (IBD) patients have many vitamin and nutrient deficiencies which can lead to important consequences such as hyperhomocysteinemia which is associated with a higher risk of thromboembolic disease. Nutritional deficiencies in IBD patients are the result of insufficient intake, malabsorption and protein-losing enteropathy as well as the metabolic distubances directly induced by the chronic disease and its treatments, in particular corticosteroids. Screening for nutritional deficiencies in chronic disease patients is warranted. Managing the deficiencies involves simple nutritional guidelines, vitamin supplements, and nutritional support in the worst cases, in particular in children in order to limit the impact of IBD on growth. In active CD, enteral nutrition is the first line therapy in children and should be used as sole therapy in adults mainly when treatment with corticosteroids is not feasible.

Diarrhoea in the enterally fed patient

Diarrhoea complicating enteral feeding is very common in all clinical settings. The major risk factor is the use of concomitant antibiotics. The underlying mechanisms for the diarrhoea mainly relate to alterations in the colonic flora and physiological responses to the mode of feed delivery although a clear understanding of what is actually happening in vivo remains elusive. Management of diarrhoea includes rationalising medications, excluding relevant comorbidity and using antidiarrhoeal medications. Altering the method and site of feed delivery-for example, continuous to bolus, gastric to postpyloric-can also be tried in the more difficult cases.

Beneficial effects of probiotic and food borne yeasts on human health

Besides being important in the fermentation of foods and beverages, yeasts have shown numerous beneficial effects on human health. Among these, probiotic effects are the most well known health effects including prevention and treatment of intestinal diseases and immunomodulatory effects. Other beneficial functions of yeasts are improvement of bioavailability of minerals through the hydrolysis of phytate, folate biofortification and detoxification of mycotoxins due to surface binding to the yeast cell wall.

ESPEN Guidelines on Parenteral Nutrition: gastroenterology

Undernutrition as well as specific nutrient deficiencies has been described in patients with Crohn's disease (CD), ulcerative colitis (UC) and short bowel syndrome. In the latter, water and electrolytes disturbances may be a major problem. The present guidelines provide evidence-based recommendations for the indications, application and type of parenteral formula to be used in acute and chronic phases of illness. Parenteral nutrition is not recommended as a primary treatment in CD and UC. The use of parenteral nutrition is however reliable when oral/enteral feeding is not possible. There is a lack of data supporting specific nutrients in these conditions. Parenteral nutrition is mandatory in case of intestinal failure, at least in the acute period. In patients with short bowel, specific attention should be paid to water and electrolyte supplementation. Currently, the use of growth hormone, glutamine and GLP-2 cannot be recommended in patients with short bowel.

Tumor necrosis factor-alpha mediates hyperglycemia-augmented gut barrier dysfunction in endotoxemia

OBJECTIVE

To examine whether hyperglycemia would augment gut barrier dysfunction and inflammatory responses in endotoxemic rats, and simultaneously to clarify the roles of tumor necrosis factor (TNF)-alpha in alterations of gut mucosal permeability associated with hyperglycemia.

DESIGN

Prospective randomized animal study.

SETTING

University research laboratory.

SUBJECTS

: Male Wistar rats treated with lipopolysaccharide (LPS) injection.

INTERVENTIONS

After LPS injection (4 mg/kg), rats were randomly allocated into group S (n = 6), group G (n = 7), or group GI (n = 8) with continuous infusion of different fluid solutions: normal saline, 40% glucose or 10% glucose mixed with insulin, respectively. Blood glucose, insulin, and proinflammatory cytokines, accompanied by gut mucosal permeability using an in situ loop preparation of gut with fluorescence isothiocyanate-conjugated dextran, were measured. Bacterial growth or alterations in mesenteric lymph nodes and cecal contents were also assessed. We further determined the roles of TNF-alpha using an inhibitor of TNF-alpha converting enzyme in gut barrier dysfunction under the same experimental settings.

MEASUREMENTS AND MAIN RESULTS

Hyperglycemia over 400 mg/dL was achieved and kept in group G during the study period whereas normoglycemia was preserved in group S and GI, the latter of which showed the similar extent of hyperinsulinemia to group G. Plasma concentrations of fluorescence-labeled dextran and TNF-alpha in group G were significantly higher vs. group S and GI, and the number of bacteria found in mesenteric lymph nodes in group G was greater compared with group S. Intestinal environments including microflora and organic acids were not altered by blood glucose or insulin level. Inhibiting conversion of membrane-bound to soluble type of TNF-alpha restored gut mucosal permeability augmented by hyperglycemia.

CONCLUSIONS

These findings indicate that hyperglycemia deteriorates LPS-elicited gut barrier dysfunction and bacterial translocation independently of plasma insulin level, and that TNF-alpha mediates such mucosal dysfunction of gut in endotoxemia.

Microbial ecology shifts in the ileum of broilers during feed withdrawal and dietary manipulations

Broilers are withheld from feed for 8 to 24 h before processing to empty the gastrointestinal tract and reduce potential carcass contamination from gastrointestinal tract contents. Intestinal microbial changes during feed withdrawal (FW) have not been thoroughly defined. Two experiments were conducted to examine the effects of diet and FW on the microbial ecology in the small intestine. In experiment 1, 42-d-old broilers were fed diets containing no additive (control), 250 ppm of CuSO(4), or bacitracin (BMD; 30 ppm) and were also subjected to FW for 0, 10, and 24 h. Six birds from each dietary treatment were killed at each FW time point and ileal mucosa and digesta were collected. Microbial communities were determined by isolating bacterial DNA, amplifying the V3 region of 16S ribosomal DNA, and performing denaturing gradient gel electrophoresis. The mucosal microbial profiles from birds at 0 h of FW had higher similarity values than those at 24 h of FW, indicating that as FW time increased, uniformity of intestinal microbial populations decreased. Numbers of bands (an indicator of numbers of bacterial species present) at 0 h (9.38) were greater than those at 10 and 24 h (5.39 and 5.78, respectively), suggesting a reduction in microbial species and diversity as FW time increased. Copper-fed birds had greater similarity coefficients than either the control or BMD-fed birds, but BMD-fed birds had greater band numbers. No interaction between diet and FW was observed and no digesta differences were observed. In experiment 2, 62-d-old birds fed corn-soy diets in floor pens were subjected to 0, 8, 12, and 24 h of FW. Ileal mucosal tissue was collected and analyzed as in experiment 1. Mucosal microbiota similarities were greater at 0 h of FW than at 8, 12, or 24 h of FW and band numbers were reduced between 0 and 24 h of FW. Data from these studies suggest that FW and dietary treatments alter the microbial community of the intestine by decreasing bacterial diversity in the ileum.

Impact of antibiotics on the gut microbiota of critically ill patients

We evaluated the relationship between the intestinal microbiota composition and clinical outcome in a group of 15 high-risk patients admitted for acute infection and/or surgical/accidental trauma who were treated with systemic antibiotics according to standard intensive care unit (ICU) protocols. There was a high mortality rate amongst these patients, each of whom had a considerable organ failure score at admission, respiratory assistance during the most of their ICU stay and a long length of stay. All of these individuals received sedation and enteral nutrition, and the majority also received insulin, vasoactive drugs and some stress-ulcer prophylaxis agents. The intestinal microbiota composition was assessed using denaturing gradient gel electrophoresis (DGGE), a molecular biology tool used to characterize bacterial ecosystems. As all of the patient subjects were in good health prior to their acute illness and admission to the ICU, the first faecal samples obtained from this group showed a DGGE banding pattern that was similar to that of healthy subjects. After 1 week of critical illness, coupled with intensive care treatment, including antibiotics, a very definite alteration in the overall microbiota composition was evident, as revealed by a reduction in the number of DGGE bands. Further pronounced changes to the DGGE banding profiles could be observed in patients remaining in the ICU for 2 weeks. Moreover, a dominant band, identified by sequencing as highly related to Enterococcus, was detected in the DGGE profile of some of our patient subjects. We also performed real-time PCR and obtained results that were in agreement with our qualitative evaluations using DGGE. The degree of organ failure and ICU mortality was significantly higher in patients for whom a high reduction in microbiota biodiversity was coupled with a massive presence of enterococci. A statistically significant link between these two ecological traits and the use of clindamycin was also found.

Enteral-tube-feeding diarrhoea: manipulating the colonic microbiota with probiotics and prebiotics

Diarrhoea is a common and serious complication of enteral tube feeding. Its pathogenesis involves antibiotic prescription, enteropathogenic colonization and abnormal colonic responses, all of which involve an interaction with the colonic microbiota. Alterations in the colonic microbiota have been identified in patients receiving enteral tube feeding and these changes may be associated with the incidence of diarrhoea. Preventing negative alterations in the colonic microbiota has therefore been investigated as a method of reducing the incidence of diarrhoea. Probiotics and prebiotics may be effective because of their suppression of enteropathogenic colonization, stimulation of immune function and modulation of colonic metabolism. Randomized controlled trials of probiotics have produced contrasting results, although Saccharomyces boulardii has been shown to reduce the incidence of diarrhoea in patients in the intensive care unit receiving enteral tube feeding. Prebiotic fructo-oligosaccharides have been shown to increase the concentration of faecal bifidobacteria in healthy subjects consuming enteral formula, although this finding has not yet been confirmed in patients receiving enteral tube feeding. Furthermore, there are no clinical trials investigating the effect of a prebiotic alone on the incidence of diarrhoea. Further trials of the efficacy of probiotics and prebiotics, alone and in combination, in preventing diarrhoea in this patient group are warranted.

Improvement of nutritional status and incidence of infection in hospitalised, enterally fed elderly by feeding of fermented milk containing probiotic Lactobacillus johnsonii La1 (NCC533)

Probiotics have potential to improve host immunity; however, there is less evidence showing their efficacy against infections and nutritional status in the elderly. We conducted a double-blinded feeding trial in the elderly to elucidate the effect of fermented milk containing Lactobacillus johnsonii La1 (LC1) on infections and nutritional status. Twenty-four completely enterally fed elderly in-patients aged over 70 years were randomly assigned into two groups. All subjects were administered 3768 kJ (900 kcal)/d of total enteral nutrition (EN) through tube feeding for 12 weeks. Subjects in the LC1 group were administered 373 kJ (89 kcal)/d of LC1 fermented milk after feeding of 3395 kJ (811 kcal)/d of EN for 12 weeks. In the control group, 373 kJ/d of the same EN was replaced from the fermented milk. In the LC1 group, the percentage of days with infections during the run-in observation period was 15.4 (SD 17.3) %, which significantly decreased to 5.7 (SD 8.1) % during the intervention period (P = 0.018), and the reduction was larger than that of the control group (P = 0.047). Blood Hb increased (P < 0.05), and there was a tendency towards an increase in serum albumin and a decrease in TNF-alpha (a pro-inflammatory cytokine) in the LC1 group. There was a trend towards an increase in blood phagocytic activity (a natural immunity marker) in the subjects whose initial level was low in the LC1 group. There were no changes in those parameters in the control group. Administration of fermented milk containing the probiotic L. johnsonii La1 may contribute to suppressing infections by improving nutritional and immunological status in the elderly.

Short-chain fatty acids: ready for prime time?

The concept of colonic health has become a major target for the development of functional foods such as probiotics, prebiotics, and synbiotics. These bioactive agents have a profound effect on the composition of the microflora, as well as on the physiology of the colon, and display distinct health benefits. Dietary carbohydrates escaping digestion/absorption in the small bowel and prebiotics undergo fermentation in the colon and give rise to short-chain fatty acids (SCFA). As the main anions of the colon and the major source of energy for colonocytes, SCFA are rapidly absorbed by nonionic diffusion mostly but also by active transport mediated by a sodium-coupled transporter, thereby fostering the absorption of sodium and water. SCFA in general and butyrate in particular enhance the growth of lactobacilli and bifidobacteria and play a central role on the physiology and metabolism of the colon. The effect of prebiotics on cell proliferation, differentiation, apoptosis, mucin production, immune function, mineral absorption, lipid metabolism, and gastrointestinal (GI) peptides has been well documented experimentally. These effects seem to be largely mediated by SCFA, but evidence from human studies remains inconsistent. The food industry is making a leap of faith in their efforts to commercialize prebiotics and exploit potential health benefits. The future lies with the design of studies to further explore basic mechanisms, and gene expression in particular, but emphasis should be placed on human intervention trials.

Effects of Saccharomyces boulardii on fecal short-chain fatty acids and microflora in patients on long-term total enteral nutrition

AIM: To assess the effects of Sb on fecal flora and short-chain fatty acids (SCFA) in patients on long-term TEN.

METHODS: Ten patients (3 females, 7 males, 59±5.5 years), on TEN for a median of 13 mo (1-125), and 15 healthy volunteers (4 females, 11 males, 32±2.0 years) received Sb (0.5 g bid PO) for 6 d. Two stool samples were taken before, on the last 2 d and 9-10 d after treatment, for SCFA measurement and for culture and bacterial identification. Values (mean±SE) were compared using sign tests and ANOVA.

RESULTS: Fecal butyrate levels were lower in patients (10.1±2.9 mmol/kg) than in controls (19.2±2.9, P = 0.02). Treatment with Sb increased total fecal SCFA levels in patients (150.2±27.2vs 107.5?8.2 mmol/kg, P = 0.02) but not in controls (129.0±28.6 vs 113.0±15.2 mmol/kg, NS). At the end of treatment with Sb, patients had higher fecal butyrate (16.0±4.4 vs 10.1 [2.9] mmol/kg, P = 0.004). Total SCFAs remained high 9 d after treatment was discon-tinued. Before the treatment, the anaerobe to aerobe ratio was lower in patients compared to controls (2.4±2.3 vs 69.8±1.8, P = 0.003). There were no significant changes in the fecal flora of TEN patients.

CONCLUSION: Sb-induced increase of fecal SCFA concentrations (especially butyrate) may explain the preventive effects of this yeast on TEN-induced diarrhea.

Colonic Crohn's disease in children does not respond well to treatment with enteral nutrition if the ileum is not involved

Data supporting a response to treatment with exclusive enteral nutrition in pediatric colonic Crohn's disease are few. We examined clinical and biochemical responses of ileal, colonic, and ileocolonic Crohn's disease and assessed the endoscopic and histological colonic mucosal response in the colonic and ileocolonic groups. We prospectively enrolled 65 children (age: 8-17 years) with acute intestinal Crohn's disease (Pediatric Crohn's Disease Activity Index [PCDAI] >20). After ileocolonoscopy, gastroscopy, and a barium meal and follow-through, they were distributed into three groups (ileal, n = 12, ileocolonic, n = 39; and colonic, n = 14). All patients received exclusive polymeric feed as treatment, with a repeat endoscopy at completion of treatment. At enrollment the ileal group had significantly less severe disease (P = 0.05) compared to the colonic and ileocolonic groups. However, the colonic disease group showed the least fall in PCDAI scores at completion of treatment with enteral nutrition (P = 0.03), with the lowest remission rate (50%, vs 82.1% in the ileocolonic and 91.7% in the ileal group [chi2 test, P = 0.021]). Endoscopic and histologic colonic mucosal assessment showed a post-treatment improvement in the ileocolonic (P < or = 0.01) but not in the colonic disease group (P = ns). Children with disease in the colon respond better to enteral nutrition if the ileum is also involved. This may be due to different underlying inflammatory mechanisms. Detailed pretreatment assessment in studies of Crohn's disease according to disease distribution with appropriate individualized tailoring of treatment may be important in this regard.

Synbiotics reduce postoperative infectious complications: a randomized controlled trial in biliary cancer patients undergoing hepatectomy

BACKGROUND AND AIMS

The clinical value of synbiotics in surgical patients remains unclear. The aim of this study was to investigate the effect of synbiotics on intestinal integrity and microflora, as well as on surgical outcome, in patients undergoing high-risk hepatectomy.

METHODS

Fifty-four patients with biliary cancer were randomly allocated to two groups before hepatectomy. One group received postoperative enteral feeding that included synbiotics; the other received enteral feeding only. Lactulose/mannitol (L/M) ratio, serum diamine oxidase (DAO) activity, and fecal microflora and organic acid concentrations were determined. Postoperative infectious complications were recorded.

RESULTS

Of the 54 patients, 44 completed the trial (21 receiving synbiotics and 23 others as controls). Postoperative changes in L/M ratios and serum DAO activities were identical between the two groups. Numbers of beneficial bacteria increased in the synbiotics group after surgery but decreased in controls. Numbers of harmful microorganisms decreased in the synbiotics group but increased in controls. Total organic acid concentrations increased in the synbiotics group but decreased in controls. Incidence of infectious complications was 19% (4/21) in the synbiotics group and 52% (12/23) in controls (P<0.05). All study patients tolerated surgery (mortality 0%).

CONCLUSIONS

Synbiotics, combined with early enteral nutrition, can reduce postoperative infections. This beneficial effect presumably involves correction of an intestinal microbial imbalance induced by surgical stress.

DNA microarray analysis of predominant human intestinal bacteria in fecal samples

A microarray method was developed for the detection of 40 bacterial species reported in the literature to be predominant in the human gastrointestinal tract. The 40 species include seven species each of Bacteroides and Clostridium, six species of Ruminococcus, five species of Bifidobacterium, four species of Eubacterium, two species each of Fusobacterium, Lactobacillus and Enterococcus, and single species each of Collinsella, Eggerthella, Escherichia, Faecalibacterium and Finegoldia. Three 40-mer oligos specific for each bacterial species were designed based on comparison of the 16S rDNA sequences available in the GenBank database, and were used to make the DNA-array on epoxy slides. Using two universal primers, the 16S rRNA gene from bacteria present in fecal samples were amplified and labeled with Cyanine5-dCTP by PCR, and then hybridized to the DNA-array. After resolving some difficulties caused by sequence conflicts in GenBank and inaccurate reference strains, all 40 bacterial reference species gave positive results. The microarray method was used to screen fecal samples obtained from 11 healthy human volunteers for the presence of these intestinal bacteria. The results indicated that 25-37 of the 40 species could be detected in each fecal sample and that 33 of the species were found in a majority of the samples.

Enteral feeding: the effect on faecal output, the faecal microflora and SCFA concentrations

Enteral tube feeding is common in both the hospital and community environment; however, patients can suffer alterations in faecal output that can have serious clinical sequelae. Problems associated with accurate characterisation of faecal output and definition of diarrhoea impede the comparison of research studies and prevent standardised assessment of therapeutic interventions in clinical practice. The colonic microflora may protect the patient against diarrhoea by preventing enteropathogenic infection and by producing SCFA that stimulate colonic water absorption. However, studies in healthy volunteers suggest that the composition of the enteral formula may have a negative impact on the microflora and SCFA concentrations. The addition of fructo-oligosaccharides to the enteral formula may partially prevent negative alterations to the microflora, although conclusive data from studies in patients are not yet available. Modification of the microflora with probiotics and prebiotics may hold potential in prophylaxis against diarrhoea during enteral tube feeding.

Risk factors for multidrug-resistant Pseudomonas aeruginosa nosocomial infection

A case-control study was conducted in a university hospital to determine the risk factors for nosocomial infection with multidrug-resistant Pseudomonas aeruginosa (MDR-PA) among all hospitalized patients and among those with a nosocomial infection due to P. aeruginosa. Eighty patients infected with MDR-PA, 75 infected with a non-MDR phenotype and 240 random controls were included in the 12-month study. Among all hospitalized patients, age, severity index, having a bedridden condition, transfer from other units, nasogastric feeding, urinary catheterization and exposure to beta-lactams (OR=2.5) or fluoroquinolones (OR=4.1) in the seven days before infection were linked to nosocomial infection due to MDR-PA. Among patients infected by P. aeruginosa, exposure to fluoroquinolones (OR=4.7) or surgery (OR=0.5) were linked to the isolation of MDR-PA. This study showed that, in addition to urinary catheterization, nasogastric feeding is an important risk factor in MDR-PA infection. Indeed, an imbalance in gut flora, modifications to the mucous membranes due to the use of nasogastric feeding and the selection pressures exerted by antibiotics were implicated in the occurrence of this infection.

Clinical experience with probiotics in the elderly on total enteral nutrition

BACKGROUND

Recent data support that after 2 years of age, intestinal microflora remains relatively constant over time, except in elderly people, who harbor fewer bifidobacteria and a higher population of fungi and enterobacteria than young adults. Diet supplementation with probiotics may improve the nutritional status and reduce the impaired immunity associated with aging. The goal of this study was to establish the effect on bifidobacteria fecal counts, and some clinical parameters, of bifidobacteria supplementation to elderly patients in total parenteral nutrition.

METHODS

Thirteen patients (6 men and 7 women; mean age, 69 years; range, 65-76 years) affected by permanent vegetative status (PVS) and fed by total enteral nutrition (TEN) were studied. Bifidobacteria and clostridia were investigated by microbiologic and molecular biology methods in stool specimens collected twice at basal time (T-2 and T0) and after 12 and 15 days (T12 and T15, respectively). Seven patients with basal bifidobacteria counts less than 10 were supplemented with Bifidobacterium longum W 11 for 12 days. The remaining 6 patients were used as control subjects. For 1 month diarrhea and fever episodes, use of antibiotics, and nutritional status (BMI) were assessed.

RESULTS

In the 7 patients with bifidobacteria counts less than 10, the administration of B. longum W 11 resulted in a 1 log increase in 6 of 7 patients at T12. No statistically significant difference in episodes of fever or diarrhea, use of antibiotics, or BMI was observed between the treatment and control groups.

CONCLUSION

The administration of B. longum W11 in PVS patients fed by TEN is effective in increasing the population of bifidobacteria. Larger studies with longer follow-up could demonstrate the influence of these microbiologic changes in a clinical setting.

Trophic and cytoprotective nutrition for intestinal adaptation, mucosal repair, and barrier function

Intestinal epithelial cell turnover (proliferation, migration, differentiation, and apoptosis) and gut barrier functions are dynamic processes that are markedly affected by nutritional status, the route of feeding, and the adequacy of specific nutrients in the diet. Emerging studies are defining potential therapeutic roles for specific nutrients and diet-derived compounds (including arginine, glutamate, glutamine, glutathione, glycine, vitamin A, zinc, and specific lipids) in gut mucosal turnover, repair, adaptation after massive bowel resection, and barrier function. The role and regulation of endogenous bowel flora in generating short-chain fatty acids from diet-derived fiber and other diet-derived compounds and the effects of these agents on gut function are increasingly being elucidated. Results of these investigations should define new nutritional methods for trophic and cytoprotective effects on the intestine in conditions such as inflammatory bowel disease, malnutrition, and short bowel syndrome.

Gut changes attributed to ageing: effects on intestinal microflora

PURPOSE OF REVIEW

There is increased evidence of several impaired gastrointestinal functions with ageing. In the elderly, however, most gastrointestinal functions remain relatively intact because of the large reserve capacity of the intestine and the great secretion capacity of the pancreas. This review will focus on changes in gut microflora observed in the elderly and on the potential benefit of probiotics in this population.

RECENT FINDINGS

Recent studies suggest that age affects the intestinal microflora with a decrease in anaerobes and bifidobacteria population and an increase in enterobacteria. These changes and the reduced intestinal immunity of the aged may favour gastrointestinal infections that are frequent in the elderly. Clostridium difficile-associated diarrhoea, one of the most common nosocomial infections in the elderly, has a profound effect on morbidity, mortality and health costs. Probiotics may have interesting positive effects on intestinal function, and the efficacy of treatment with Lactobacilli and Saccharomyces boulardii in Clostridium difficile-associated diarrhoea has been well established in a recent meta-analysis. Studies performed in healthy elderly patients suggest that diet supplementation with probiotics may reduce the impaired immunity associated with ageing.

SUMMARY

Important changes in intestinal microflora of the elderly have recently been demonstrated and may have important clinical consequences. Further studies should be conducted to determine if the consumption of probiotics is associated with a lower infection rate and a higher effectiveness of vaccines.

Development of a membrane-array method for the detection of human intestinal bacteria in fecal samples

A membrane-array method was developed for the detection of human intestinal bacteria in fecal samples without using the expensive microarray-arrayer and laser-scanner. The 16S rDNA sequences of 20 predominant human intestinal bacterial species were used to design oligonucleotide probes. Three 40-mer oligonucleotides specific for each bacterial species (total 60 probes) were synthesized and applied to nitrocellulose membranes. Digoxigenin (DIG)-labeled 16S rDNAs were amplified by polymerase chain reaction (PCR) from human fecal samples or pure cultured bacteria using two universal primers, and were hybridized to the membrane-array. Hybridization signals were read by NBT/BCIP color development. The 20 intestinal bacterial species tested were Bacteroides thetaiotaomicron, B. vulgatus, B. fragilis, B. distasonis, Clostridium clostridiiforme, C. leptum, Fusobacterium prausnitzii, Peptostreptococcus productus, Ruminococcus obeum, R. bromii, R. callidus, R. albus, Bifidobacterium longum, B. adolescentis, B. infantis, Eubacterium biforme, E. aerofaciens, Lactobacillus acidophilus,Escherichia coli, and Enterococcus faecium. The two universal primers were able to amplify full size 16S rDNA from all of the 20 bacterial species tested. The hybridization results indicated that the membrane-array method is a reliable technique for the detection of predominant human intestinal bacteria in the fecal samples. The result was also confirmed by using specific PCR methods for these bacteria.

Design and evaluation of oligonucleotide-microarray method for the detection of human intestinal bacteria in fecal samples

An oligonucleotide-microarray method was developed for the detection of intestinal bacteria in fecal samples collected from human subjects. The 16S rDNA sequences of 20 predominant human intestinal bacterial species were used to design oligonucleotide probes. Three 40-mer oligonucleotides specific for each bacterial species (total 60 probes) were synthesized and applied to glass slides. Cyanine5 (CY5)-labeled 16S rDNAs were amplified by polymerase chain reaction (PCR) from human fecal samples or bacterial DNA using two universal primers and were hybridized to the oligo-microarray. The 20 intestinal bacterial species tested were Bacteroides thetaiotaomicron, Bacteroides vulgatus, Bacteroides fragilis, Bacteroides distasonis, Clostridium clostridiiforme, Clostridium leptum, Fusobacterium prausnitzii, Peptostreptococcus productus, Ruminococcus obeum, Ruminococcus bromii, Ruminococcus callidus, Ruminococcus albus, Bifidobacterium longum, Bifidobacterium adolescentis, Bifidobacterium infantis, Eubacterium biforme, Eubacterium aerofaciens, Lactobacillus acidophilus, Escherichia coli, and Enterococcus faecium. The two universal primers were able to amplify full size 16S rDNA from all of the 20 bacterial species tested. The hybridization results indicated that the oligo-microarray method developed in this study is a reliable method for the detection of predominant human intestinal bacteria in the fecal samples.