Updated meta-analysis of probiotics for preventing necrotizing enterocolitis in preterm neonates

Bifidobacteria: their impact on gut microbiota composition and their applications as probiotics in infants

This review is aimed at describing the most recent advances in the gut microbiota composition of newborns and infants with a particular emphasis on bifidobacteria. The newborn gut microbiota is quite unstable, whereas after weaning, it becomes more stable and gets closer to the typical adult microbiota. The newborn and infant gut microbiota composition is impaired in several enteric and non-enteric pathologies. The core of this review is the description of the most recent documented applications of bifidobacteria to newborns and infants for their prevention and treatment. Acute diarrhea is the most studied disease for which bifidobacteria are applied with great success, Bifidobacterium longum and Bifidobacterium breve being the most applied species. Moreover, the most recent updates in the use of bifidobacteria for the prevention and treatment of pathologies typical of newborns, such as necrotizing enterocolitis, colics, and streptococcal infections, are presented. In addition, a number of not strictly enteric pathologies have in recent years evidenced a strict correlation with an aberrant gut microbiota in infants, in particular showing a reduced level of bifidobacteria. These diseases represent new potential opportunities for probiotic applications. Among them, allergic diseases, celiac disease, obesity, and neurologic diseases are described in this review. The preliminary use of bifidobacteria in in vitro systems and animal models is summarized as well as preliminary in vivo studies. Only after validation of the results via human clinical trials will the potentiality of bifidobacteria in the prevention and cure of these pathologies be definitely assessed.

Bacterial colonization and intestinal mucosal barrier development

The intestinal tract is colonized soon after birth with a variety of ingested environmental and maternal microflora. This process is influenced by many factors including mode of delivery, diet, environment, and the use of antibiotics. Normal intestinal microflora provides protection against infection, ensures tolerance to foods, and contributes to nutrient digestion and energy harvest. In addition, enteral feeding and colonization with the normal commensal flora are necessary for the maintenance of intestinal barrier function and play a vital role in the regulation of intestinal barrier function. Intestinal commensal microorganisms also provide signals that foster normal immune system development and influence the ensuing immune responses. There is increasingly recognition that alterations of the microbial gut flora and associated changes in intestinal barrier function may be related to certain diseases of the gastrointestinal tract. This review summarizes recent advances in understanding the complex ecosystem of intestinal microbiota and its role in regulating intestinal barrier function and a few common pediatric diseases. Disruption in the establishment of a stable normal gut microflora may contribute to the pathogenesis of diseases including inflammatory bowel disease, nosocomial infection, and neonatal necrotizing enterocolitis.

Probiotics, feeding tolerance, and growth: a comparison between HIV-exposed and unexposed very low birth weight infants

OBJECTIVE

The aim of this study was to compare the effect of administration of probiotics on feeding tolerance and growth outcomes of HIV-exposed (but uninfected) versus HIV non-exposed preterm infants. The null hypothesis of this study states that there will be no difference in the feeding tolerance and growth outcomes for both probiotic-exposed and unexposed premature very low birth weight infants.

METHODS

A randomized, double-blind, placebo-controlled trial was conducted during the period from July 2011 to August 2012. HIV-exposed and non-exposed premature (<34 wk gestation) infants with a birth weight of ≥500 g and ≤1250 g were randomized to receive either a probiotic mixture or placebo. The multispecies probiotic mixture consisted of 1 × 10(9) CFU, Lactobacillus rhamnosus GG and Bifidobacterium infantis per day and was administered for 28 d. Anthropometrical parameters, daily intakes, and feeding tolerance were monitored.

RESULTS

Seventy-four HIV-exposed and 110 unexposed infants were enrolled and randomized (mean birth weight 987 g ± 160 g, range, 560-1244 g; mean gestational age 28.7 wk). In all 4227 probiotic doses were administered (mean 22.9/infant). There was no difference in the average daily weight gain for treatment groups or HIV exposure. The HIV-exposed group achieved significantly higher z scores for length and head circumference at day 28 than the unexposed group (P < 0.01 and P = 0.03, respectively). There were no differences in the incidence of any signs of feeding intolerance and abdominal distension between the groups.

CONCLUSION

Probiotic supplementation did not affect growth outcomes or the incidence of any signs of feeding intolerance in HIV exposure.

Necrotizing enterocolitis: have we made any progress in reducing the risk?

Necrotizing enterocolitis (NEC) is a disease affecting premature infants with potentially devastating complications in the neonatal intensive care unit (NICU). Inadequate knowledge regarding the underlying pathophysiology of this disease has contributed to the minimal progress made in decreasing the incidence and severity of NEC. Because of an improved survival rate of the most immature infants, the number of diagnosed cases of NEC is anticipated to increase. Unfortunately, decades of research have failed to reduce the risk or improve the prognosis of NEC, magnifying the need for risk-reduction strategies for decreasing significant NEC-related morbidity and mortality. Advancements in our understanding of this disease process have facilitated the development of several strategies that have been investigated in the risk reduction of NEC. This article discusses the pathophysiology and causes of NEC and presents strategies investigated regarding risk reduction of this devastating disease.

Feeding intolerance in the preterm infant

Feeding intolerance (FI), defined as the inability to digest enteral feedings associated to increased gastric residuals, abdominal distension and/or emesis, is frequently encountered in the very preterm infant and often leads to a disruption of the feeding plan. In most cases FI represents a benign condition related to the immaturity of gastrointestinal function, however its presentation may largely overlap with that of an impending necrotizing enterocolitis. As a consequence, individual interpretation of signs of FI represents one of the most uncontrollable variables in the early nutritional management of these infants, and may lead to suboptimal nutrition, delayed attainment of full enteral feeding and prolonged intravenous nutrition supply. Strategies aimed at preventing and/or treating FI are diverse, although very few have been validated in large RCT and systematic reviews. The purpose of this paper is to summarize the existing information on this topic, spanning from patho-physiological and clinical aspects to the prevention and treatment strategies tested in clinical studies, with specific attention to practical issues.

A Pocock approach to sequential meta-analysis of clinical trials

Three recent papers have provided sequential methods for meta-analysis of two-treatment randomized clinical trials. This paper provides an alternate approach that has three desirable features. First, when carried out prospectively (i.e., we only have the results up to the time of our current analysis), we do not require knowledge of the information fraction (the fraction of the total information that is available at each analysis). Second, the methods work even if the expected values of the effect sizes vary from study to study. Finally, our methods have easily interpretable metrics that make sense under changing effect sizes. Although the other published methods can be adapted to be “group sequential” (recommended), meaning that a set number and timing of looks are specified, rather than looking after every trial, ours can be used in both a continuous or group sequential manner. We provide an example on the role of probiotics in preventing necrotizing enterocolitis in preterm infants.

Probiotic administration in congenital heart disease: a pilot study

OBJECTIVE

To investigate the impact of probiotic Bifidobacterium longum ssp. infantis on the fecal microbiota and plasma cytokines in neonates with congenital heart disease.

STUDY DESIGN

Sixteen infants with congenital heart disease were randomly assigned to receive either B. infantis (4.2 × 10(9) colony-forming units two times daily) or placebo for 8 weeks. Stool specimens from enrolled infants and from six term infants without heart disease were analyzed for microbial composition. Plasma cytokines were analyzed weekly in the infants with heart disease.

RESULTS

Healthy control infants had increased total bacteria, total Bacteroidetes and total bifidobacteria compared to the infants with heart disease, but there were no significant differences between the placebo and probiotic groups. Plasma interleukin (IL)10, interferon (IFN)γ and IL1β levels were transiently higher in the probiotic group.

CONCLUSION

Congenital heart disease in infants is associated with dysbiosis. Probiotic B. infantis did not significantly alter the fecal microbiota. Alterations in plasma cytokines were found to be inconsistent.

Microbial activation of gut dendritic cells and the control of mucosal immunity

Current data support a role for gut colonization in maintaining balanced mucosal and systemic immune responses and have suggested aberrant innate immune recognition of enteric bacteria as an initiator of the adaptive immune damage associated with inflammatory bowel disease (Crohn's disease and ulcerative colitis). In fact, data from human studies and experimental mouse models have implicated transformation of the gut microbiota from a beneficial symbiotic state to one of imbalance or "dysbiosis" in the pathogenesis of several autoinflammatory diseases, including allergic skin and respiratory disorders, rheumatoid arthritis, type I diabetes, and colorectal cancer. The host has evolved to co-exist and maintain a mutualistic relationship with the commensal microbes of the gut, and it is the function of the host innate immune system to initiate and maintain this homeostasis, while retaining the ability to respond appropriately to pathogenic organisms. In this review, we discuss the molecular and cellular interactions of the mucosal immune system that decide this delicate balance of mutualism. Furthermore, we will highlight the role of dendritic cells in preserving this precarious balance and how gene products of commensal microbes may play an integral role in re-establishing this balance once it has gone awry.

Microbial activation of gut dendritic cells and the control of mucosal immunity

Current data support a role for gut colonization in maintaining balanced mucosal and systemic immune responses and have suggested aberrant innate immune recognition of enteric bacteria as an initiator of the adaptive immune damage associated with inflammatory bowel disease (Crohn's disease and ulcerative colitis). In fact, data from human studies and experimental mouse models have implicated transformation of the gut microbiota from a beneficial symbiotic state to one of imbalance or "dysbiosis" in the pathogenesis of several autoinflammatory diseases, including allergic skin and respiratory disorders, rheumatoid arthritis, type I diabetes, and colorectal cancer. The host has evolved to co-exist and maintain a mutualistic relationship with the commensal microbes of the gut, and it is the function of the host innate immune system to initiate and maintain this homeostasis, while retaining the ability to respond appropriately to pathogenic organisms. In this review, we discuss the molecular and cellular interactions of the mucosal immune system that decide this delicate balance of mutualism. Furthermore, we will highlight the role of dendritic cells in preserving this precarious balance and how gene products of commensal microbes may play an integral role in re-establishing this balance once it has gone awry.

Microbial activation of gut dendritic cells and the control of mucosal immunity

Current data support a role for gut colonization in maintaining balanced mucosal and systemic immune responses and have suggested aberrant innate immune recognition of enteric bacteria as an initiator of the adaptive immune damage associated with inflammatory bowel disease (Crohn's disease and ulcerative colitis). In fact, data from human studies and experimental mouse models have implicated transformation of the gut microbiota from a beneficial symbiotic state to one of imbalance or "dysbiosis" in the pathogenesis of several autoinflammatory diseases, including allergic skin and respiratory disorders, rheumatoid arthritis, type I diabetes, and colorectal cancer. The host has evolved to co-exist and maintain a mutualistic relationship with the commensal microbes of the gut, and it is the function of the host innate immune system to initiate and maintain this homeostasis, while retaining the ability to respond appropriately to pathogenic organisms. In this review, we discuss the molecular and cellular interactions of the mucosal immune system that decide this delicate balance of mutualism. Furthermore, we will highlight the role of dendritic cells in preserving this precarious balance and how gene products of commensal microbes may play an integral role in re-establishing this balance once it has gone awry.

Evaluating the impact of database heterogeneity on observational study results

Clinical studies that use observational databases to evaluate the effects of medical products have become commonplace. Such studies begin by selecting a particular database, a decision that published papers invariably report but do not discuss. Studies of the same issue in different databases, however, can and do generate different results, sometimes with strikingly different clinical implications. In this paper, we systematically study heterogeneity among databases, holding other study methods constant, by exploring relative risk estimates for 53 drug-outcome pairs and 2 widely used study designs (cohort studies and self-controlled case series) across 10 observational databases. When holding the study design constant, our analysis shows that estimated relative risks range from a statistically significant decreased risk to a statistically significant increased risk in 11 of 53 (21%) of drug-outcome pairs that use a cohort design and 19 of 53 (36%) of drug-outcome pairs that use a self-controlled case series design. This exceeds the proportion of pairs that were consistent across databases in both direction and statistical significance, which was 9 of 53 (17%) for cohort studies and 5 of 53 (9%) for self-controlled case series. Our findings show that clinical studies that use observational databases can be sensitive to the choice of database. More attention is needed to consider how the choice of data source may be affecting results.

The gut mucosal immune system in the neonatal period

Invasive sepsis in the newborn period is a major cause of childhood morbidity and mortality worldwide. The infant immune system undoubtedly differs intrinsically from the mature adult immune system. Current understanding is that the newborn infant immune system displays a range of competencies and is developing rather than deficient. The infant gut mucosal immune system is complex and displays a plethora of phenotypic and functional irregularities that may be clinically important. Various factors affect and modulate the infant gut mucosal immune system: components of the intestinal barrier, the infant gut microbiome, nutrition and the maternal-infant hybrid immune system. Elucidation of the phenotypic distribution of immune cells, their functional significance and the mucosa-specific pathways used by these cells is essential to the future of research in the field of infant immunology.

Efficacy of different probiotic combinations on death and necrotizing enterocolitis in a premature rat model

OBJECTIVE

The aim of the present study was to investigate the most effective probiotic combinations to prevent death and necrotizing enterocolitis (NEC) in a premature rat model.

METHODS

One hundred fifty-eight premature Sprague-Dawley premature rats were enrolled. Probiotic strains Bifidobacterium bifidum, B longum, Lactobacillus acidophilus, L plantarum, and B breve were fed as a single strain or mixture with 2 or 3 strains for a total of 9 study groups; control groups received no exogenous probiotic supplement. Fecal samples were collected for 72 hours to detect probiotic strains and pathologic strains by real-time polymerase chain reaction. Colony counts of probiotic strains Escherichia coli and Klebsiella were compared between groups before and after 36 hours of the study period. The incidence of death and NEC were compared via Fisher exact test between groups.

RESULTS

The results demonstrated that L plantarum alone (P = 0.0026) and B bifidum with B longum together (P = 0.0017) were more effective in reducing NEC as compared with the control group. All of the study groups except B breve and B bifidum with B breve definitely prevented death compared with controls. B bifidum and B longum together had significantly lower mortality than the control group (P < 0.0001). Colony counts of E coli and Klebsiella in stool samples were significantly decreased in the B bifidum, B longum, and L plantarum group compared with the other study and control groups after 36 hours.

CONCLUSIONS

Administration of a mixture of probiotic strains with B bifidum and B longum was most effective in preventing death and NEC in this animal model, and these observations provide an evidence-based strategy for designing further neonatal clinical trials.

Current status and future promise of the human microbiome

The human-associated microbiota is diverse, varies between individuals and body sites, and is important in human health. Microbes in human body play an essential role in immunity, health, and disease. The human microbiome has been studies using the advances of next-generation sequencing and its metagenomic applications. This has allowed investigation of the microbial composition in the human body, and identification of the functional genes expressed by this microbial community. The gut microbes have been found to be the most diverse and constitute the densest cell number in the human microbiota; thus, it has been studied more than other sites. Early results have indicated that the imbalances in gut microbiota are related to numerous disorders, such as inflammatory bowel disease, colorectal cancer, diabetes, and atopy. Clinical therapy involving modulating of the microbiota, such as fecal transplantation, has been applied, and its effects investigated in some diseases. Human microbiome studies form part of human genome projects, and understanding gleaned from studies increase the possibility of various applications including personalized medicine.

Necrotizing enterocolitis: pathophysiology, platelet-activating factor, and probiotics

Although smaller and younger preterm neonates can now survive long term due to advances in neonatal medicine, necrotizing enterocolitis (NEC) continues to plague the clinicians caring for these tiny patients. Research studies have contributed to our understanding of this complex disease, including the role of platelet-activating factor (PAF), but preventative and treatment strategies remain limited. One promising preventative measure in recent years has been enteral supplementation of probiotics, but concerns remain regarding the optimal use of these organisms, and safe administration must be assured. This chapter reviews NEC pathophysiology, including the role of PAF, as well as literature on the use of probiotics in the preterm infant.

Evidence-based prevention and surgical treatment of necrotizing enterocolitis-a review of randomized controlled trials

Necrotizing enterocolitis remains a common cause of morbidity and mortality in the neonatal period. Despite many advances in the management of the critically ill neonate, the exact etiology, attempts at prevention and determining best treatment for NEC have been elusive. Unfortunately, the overall survival for this poorly understood and complex condition has not improved. NEC is a condition that can and should be studied with randomized prospective trials (RCTs). This chapter reviews the current evidence-based trials for this condition thus far performed.

Probiotics and the mechanism of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a severe intestinal inflammatory disorder in newborns. Although the pathogenesis of NEC is not completely understood, we reviewed the literature and our previous studies to explore the mechanism of NEC and to evaluate the role for probiotics in this disease. NEC may be associated with an inappropriate innate immune and excessive inflammatory response of the immature intestine. Probiotics are widely used in promoting human health and adjunctive therapy of human disease. There are growing clinical trials and research studies that support a beneficial role for probiotics for NEC. We have reviewed the literature associated with the use of probiotics in NEC.

Neonatal infectious diseases: evaluation of neonatal sepsis

Neonatal sepsis remains a feared cause of morbidity and mortality in the neonatal period. Maternal, neonatal, and environmental factors are associated with risk of infection, and a combination of prevention strategies, judicious neonatal evaluation, and early initiation of therapy are required to prevent adverse outcomes. This article reviews recent trends in epidemiology and provides an update on risk factors, diagnostic methods, and management of neonatal sepsis.

Distribution dynamics of recombinant Lactobacillus in the gastrointestinal tract of neonatal rats

One approach to deliver therapeutic agents, especially proteins, to the gastro-intestinal (GI) tract is to use commensal bacteria as a carrier. Genus Lactobacillus is an attractive candidate for use in this approach. However, a system for expressing exogenous proteins at a high level has been lacking in Lactobacillus. Moreover, it will be necessary to introduce the recombinant Lactobacillus into the GI tract, ideally by oral administration. Whether orally administered Lactobacillus can reach and reside in the GI tract has not been explored in neonates. In this study, we have examined these issues in neonatal rats. To achieve a high level of protein expression in Lactobacillus, we tested the impact of three promoters and two backbones on protein expression levels using mRFP1, a red fluorescent protein, as a reporter. We found that a combination of an L-lactate dehydrogenase (ldhL) promoter of Lactobacillus sakei with a backbone from pLEM415 yielded the highest level of reporter expression. When this construct was used to transform Lactobacillus casei, Lactobacillus delbrueckii and Lactobacillus acidophilus, high levels of mRFP1 were detected in all these species and colonies of transformed Lactobacillus appeared pink under visible light. To test whether orally administered Lactobacillus can be retained in the GI tract of neonates, we fed the recombinant Lactobacillus casei to neonatal rats. We found that about 3% of the bacteria were retained in the GI tract of the rats at 24 h after oral feeding with more recombinant Lactobacillus in the stomach and small intestine than in the cecum and colon. No mortality was observed throughout this study with Lactobacillus. In contrast, all neonatal rats died within 24 hours after fed with transformed E. coli. Taken together, our results indicate that Lactobacillus has the potential to be used as a vehicle for the delivery of therapeutic agents to neonates.

Therapeutic use of prebiotics, probiotics, and postbiotics to prevent necrotizing enterocolitis: what is the current evidence?

Necrotizing enterocolitis (NEC) is a leading cause of neonatal morbidity and mortality, and preventive therapies that are both effective and safe are urgently needed. Current evidence from therapeutic trials suggests that probiotics are effective in decreasing NEC in preterm infants, and probiotics are currently the most promising therapy for this devastating disease. However, concerns regarding safety and optimal dosing have limited the widespread adoption of routine clinical use of probiotics in preterm infants. This article summarizes the current evidence regarding the use of probiotics, prebiotics, and postbiotics in the preterm infant, including their therapeutic role in preventing NEC.

The altered gut microbiome and necrotizing enterocolitis

Current evidence highlights the importance of developing a healthy intestinal microbiota in the neonate. Many aspects that promote health or disease are related to the homeostasis of these intestinal microbiota. Their delicate equilibrium could be strongly influenced by the intervention that physicians perform as part of the medical care of the neonate, especially preterm infants. As awareness of the importance of the development and maintenance of these intestinal flora increase and newer molecular techniques are developed, it will be possible to provide better care of infants with interventions that will have long-lasting effects.

Strategies to improve feeding tolerance in preterm infants

Postnatal growth restriction and failure to thrive is a major issue in preterm, especially extremely low-birth-weight infants. Optimization of enteral nutrition, without increasing the risk of necrotizing enterocolitis (NEC), has thus become a priority for the neonatologist, who often has to face the challenge of interpreting the clinical and prognostic significance of common and aspecific signs of feeding intolerance (FI). The neonatologist often prescribes enteral nutrition as if walking on a tightrope between the purposed attainment of full enteral feeding and the fear of NEC. Despite advances in neonatal intensive care, NEC still remains one of the leading causes of mortality (15-30%) and morbidity in very-low-birth-weight infants. However, the relationship between FI and NEC remains unknown. Feeding intolerance often leads to discontinuation of enteral feeds, delayed attainment of full enteral feeding and prolongation of hospitalization. Strategies aimed at preventing and/or treating episodes of feeding intolerance are diverse and not always supported by scientific evidence.

Probiotics: a new frontier for infection control

Probiotics are live micro-organisms administered to provide health benefits. Probiotics are being increasingly used in healthcare contexts both in research studies and routine practice, for example in neonatal intensive care. Currently there is a paucity of guidelines or regulations governing the mitigation of infection risks associated with the use of probiotics in clinical practice. We propose a number of recommendations to mitigate risks. These include the communication of probiotic use to appropriate stakeholders, ensuring that routine laboratories can identify and test the susceptibility of probiotic strains, assuring standards for preparation and administration, and ensuring surveillance designed to capture adverse events.

Enteral L-arginine supplementation for prevention of necrotizing enterocolitis in very low birth weight neonates: a double-blind randomized pilot study of efficacy and safety

BACKGROUND

Necrotizing enterocolitis (NEC) is the most common acquired gastrointestinal disease in premature infants and has high mortality and morbidity. Endothelial nitric oxide is an important regulator of vascular perfusion and is synthetized from the amino acid L-arginine. Hypoargininemia is frequently observed in preterm neonates and may predispose them to NEC. Our objective was to determine the effect of enteral L-arginine supplementation on the incidence and severity of NEC in very low birth weight (VLBW) neonates.

MATERIALS AND METHODS

We conducted a parallel blind randomized pilot study, comprising VLBW neonates with birth weight ≤1500 g and gestational age ≤34 weeks. VLBW neonates were randomly assigned to receive enteral L-arginine supplementation (1.5 mmol/kg/d bid) between the 3rd and 28th day of life or placebo. Diagnosis and classification of NEC were done according to modified Bell's criteria.

RESULTS

Eighty-three neonates were randomized to the arginine (n = 40) or placebo (n = 43) group. No adverse effects were observed in neonates receiving L-arginine supplementation. The incidence of NEC stage III was significantly lower in the arginine-supplemented group (2.5% vs 18.6%, P = .030).

CONCLUSIONS

Enteral L-arginine supplementation of 1.5 mmol/kg/d bid can be safely administered in VLBW neonates from the 3rd to the 28th day of life. Enteral L-arginine supplementation appears to reduce the incidence of stage III NEC in VLBW infants. Larger studies are needed to further evaluate the effect of L-arginine supplementation in preventing NEC in VLBW infants.

Probiotics prevent necrotizing enterocolitis by modulating enterocyte genes that regulate innate immune-mediated inflammation

Necrotizing enterocolitis (NEC), an extensive intestinal inflammatory disease of premature infants, is caused, in part, by an excessive inflammatory response to initial bacterial colonization due to the immature expression of innate immune response genes. In a randomized placebo-controlled clinical trial, supplementation of very low birth weight infants with probiotics significantly reduced the incidence of NEC. The primary goal of this study was to determine whether secreted products of these two clinically effective probiotic strains, Bifidobacterium infantis and Lactobacillus acidophilus, prevented NEC by accelerating the maturation of intestinal innate immune response genes and whether both strains are required for this effect. After exposure to probiotic conditioned media (PCM), immature human enterocytes, immature human intestinal xenografts, and primary enterocyte cultures of NEC tissue (NEC-IEC) were assayed for an IL-8 and IL-6 response to inflammatory stimuli. The latter two models were also assayed for innate immune response gene expression. In the immature xenograft, PCM exposure significantly attenuated LPS and IL-1β-induced IL-8 and IL-6 expression, decreased TLR2 mRNA and TLR4 mRNA, and increased mRNA levels of specific negative regulators of inflammation, SIGIRR and Tollip. In NEC-IEC, PCM decreased TLR2-dependent IL-8 and IL-6 induction and increased SIGIRR and Tollip expression. The attenuated inflammatory response with PCM was reversed with Tollip siRNA-mediated knockdown. The anti-inflammatory secreted factor is a 5- to 10-kDa molecule resistant to DNase, RNase, protease, heat stress, and acid exposure. B. infantis-conditioned media showed superior anti-inflammatory properties to that of L. acidophilus in immature human enterocytes, suggesting a strain specificity to this effect. We conclude that PCM promotes maturation of innate immune response gene expression, potentially explaining the protective effects of probiotics in clinical NEC.

Probiotics and prebiotics: role in prevention of nosocomial sepsis in preterm infants

Nosocomial sepsis is associated with increased mortality and morbidity including neurodevelopmental impairment and prolonged hospital stay. Prevention of sepsis especially in the preterm infants in the neonatal intensive care unit remains a major challenge. The gastrointestinal tract is an important source of potential pathogens causing nosocomial sepsis as the immature intestinal epithelium can permit translocation of bacteria and yeast. The intestinal tract and its microflora play an important role in the immunity. Altering the gut microflora has been extensively studied for immunomodulation in preterm infants. Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. Probiotics have been used for prevention and treatment of various medical conditions in children and adults. Studies on probiotics in premature infants have focused on normalizing intestinal flora, improvement in feeding intolerance, prevention of necrotizing enterocolitis and sepsis. In this paper, we discuss the intestinal bacterial colonization pattern; the rational for probiotics and prebiotic therapy with special focus on the prevention of nosocomial sepsis in preterm infants.

Effectiveness of probiotics in the prophylaxis of necrotizing enterocolitis in preterm neonates: a systematic review and meta-analysis

OBJECTIVE

To elucidate the benefits of using probiotics in the prevention of necrotizing enterocolitis (NEC) and its complications in preterm newborns.

METHOD

This was a systematic review of randomized controlled trials, which included studies retrieved from three databases (MEDLINE, Embase, and LILACS), using a combination of the terms (necrotizing enterocolitis) AND (probiotics).

RESULTS

11 randomized trials were included, totaling 2,887 patients, 1,431 in the probiotic group and 1,456 in the control group. There was a reduction in the incidence of NEC (NNT=25), overall death (NNT=34), and neonatal sepsis (NNT=34) in the probiotic group compared to the control group. Patients that received probiotic supplementation had lower food reintroduction time (p<0.001) and hospitalization time (p<0.001) when compared to those not receiving probiotics. There was no difference in mortality caused by NEC.

CONCLUSION

In premature newborns, the use of probiotics is effective as a prophylaxis for NEC and its complications.

Probiotics supplementation increases intestinal blood flow velocity in extremely low birth weight preterm infants

OBJECTIVE

To determine whether probiotics supplementation affects intestinal blood flow velocity in extremely low birth weight neonates.

STUDY DESIGN

In this randomized, double-blind, placebo-controlled study, probiotics were added to the first enteral feeding and continued until discharge or 34 weeks postmenstrual age. Pulsed Doppler was used to measure preprandial and postprandial (at 30 and 60 min) time-averaged mean velocity (TAMV), peak systolic velocity (PSV) and end diastolic velocity (EDV) during the second week of life after ≥ 7 days of probiotics supplementation.

RESULT

A total of 31 infants were studied, 15 were randomized to the probiotic and 16 to the placebo groups. There was a significant postprandial increase in TAMV for the probiotic vs the placebo group (P=0.035), with PSV and EDV showing a trend. Demographic and clinical variables were similar between the groups.

CONCLUSION

Probiotics administration significantly increases postprandial intestinal blood flow in extremely low birth weight preterm neonates when compared with the placebo group.

Pro- und Präbiotika

Die rasante Entwicklung der Molekularbiologie und eine inzwischen beachtliche Fülle an Daten aus klinischen Studien haben in der vergangenen Dekade eine neue solide wissenschaftliche Basis für den Einsatz probiotischer Bakterien, speziell von Laktobazillen und Bifidobakterien ergeben. Entgegen manchen Postulierungen existiert jedoch ganz offenkundig sowohl in experimentellen als auch in klinischen Studien eine strenge Stammspezifik von Funktionen und Wirkungen dieser Spezies probiotischer Bakterien. Eine wissenschaftliche Rationale für die Nutzung von Laktobazillen und Bifidobakterien als Probiotika ist bisher nur für vergleichsweise wenige Stämme nachgewiesen worden. Dies gilt für lebende und hitzebehandelte Bakterien gleichermaßen, ob mit oder ohne Mitverwendung ihres Kulturüberstands in den Studienansätzen.

Functions of intestinal microflora in children

PURPOSE OF REVIEW

This review discusses the structural composition of intestinal microbiota, the functional relationship between the latter and the host, and the role of abnormal microflora in chronic diseases.

RECENT FINDINGS

A more complete view of the gut microbiota is being developed following the Human Microbiome Project. The microflora in children is plastic, susceptible to changes in response to diet modifications, antibiotic treatment and other events, providing the opportunity to study its functional role. Increasing evidence highlights the role of nutrition in the age-related development of microflora. Eubiosis, that is, a normal microflora structure, provides protection against infections, educates the immune system, ensures tolerance to foods, and contributes to nutrient digestion and energy harvest. Changes in microflora, consisting in the overpresence of harmful species or underpresence of commensal species, or dysbiosis produce dysfunctions, such as intestinal inflammation or dysmotility. Moreover abnormal pattern of microflora have been consistently detected in specific diseases.

SUMMARY

A relationship exists between eubiosis and functions and conversely between dysbiosis and dysfunctions or even diseases. Abnormalities in microflora composition may trigger or contribute to specific diseases. This raises the hypothesis to target microflora in order to restore eubiosis through the use of antibiotics, probiotics or nutrients.

Probiotic prophylaxis after pullthrough for Hirschsprung disease to reduce incidence of enterocolitis: a prospective, randomized, double-blind, placebo-controlled, multicenter trial

OBJECTIVE

Hirschsprung-associated enterocolitis (HAEC) is one of the most troublesome problems encountered after a pullthrough. We hypothesized that prophylactic administration of probiotics after a pullthrough procedure would decrease the incidence of HAEC.

STUDY DESIGN

A prospective, double-blind, placebo-controlled, randomized trial was conducted at 2 children's hospitals. Infants undergoing pullthrough were randomized to probiotic or placebo for a period of 3 months post-pullthrough. Primary outcome was incidence of post-operative HAEC. Other outcomes included severity of HAEC by clinical grade, number of HAEC episodes and extent of aganglionosis. Pearson Chi Square analysis, as well as logistic regression, was used for statistical analysis.

RESULTS

Sixty-two patients were recruited (Sites: A=40; B=22). One was lost to follow up and one immediate post-op death was not included in final analysis. Probiotics were administered to 32 patients. Distribution of placebo/probiotics was equal between sites (P=0.858). Mean age at pullthrough was 6.5 ± 8.1(± SD) months. The incidence of HAEC was 28.3%. The incidence of HAEC was not statistically different between probiotic and placebo study groups.

CONCLUSIONS

Incidence of HAEC was not reduced with prophylactic probiotics. Future studies are needed to better determine the etiology and possible ways of preventing this complex condition.

Lactobacillus rhamnosus (LGG) regulates IL-10 signaling in the developing murine colon through upregulation of the IL-10R2 receptor subunit

The intestinal microflora is critical for normal development, with aberrant colonization increasing the risk for necrotizing enterocolitis (NEC). In contrast, probiotic bacteria have been shown to decrease its incidence. Multiple pro- and anti-inflammatory cytokines have been identified as markers of intestinal inflammation, both in human patients with NEC and in models of immature intestine. Specifically, IL-10 signaling attenuates intestinal responses to gut dysbiosis, and disruption of this pathway exacerbates inflammation in murine models of NEC. However, the effects of probiotics on IL-10 and its signaling pathway, remain poorly defined. Real-time PCR profiling revealed developmental regulation of MIP-2, TNF-α, IL-12, IL-10 and the IL-10R2 subunit of the IL-10 receptor in immature murine colon, while the expression of IL-6 and IL-18 was independent of postnatal age. Enteral administration of the probiotic Lactobacillus rhamnosus GG (LGG) down-regulated the expression of TNF-α and MIP-2 and yet failed to alter IL-10 mRNA and protein expression. LGG did however induce mRNA expression of the IL-10R2 subunit of the IL-10 receptor. IL-10 receptor activation has been associated with signal transducer and activator of transcription (STAT) 3-dependent induction of members of the suppressors of cytokine signaling (SOCS) family. In 2 week-old mice, LGG also induced STAT3 phosphorylation, increased colonic expression of SOCS-3, and attenuated colonic production of MIP-2 and TNF-α. These LGG-dependent changes in phosphoSTAT3, SOCS3, MIP-2 and TNF-α were all inhibited by antibody-mediated blockade of the IL-10 receptor. Thus LGG decreased baseline proinflammatory cytokine expression in the developing colon through upregulation of IL-10 receptor-mediated signaling, most likely due to the combined induction of phospho-STAT3 and SOCS3. Furthermore, LGG-dependent increases in IL-10R2 were associated with reductions in TNF-α, MIP-2 and disease severity in a murine model of intestinal injury in the immature colon.

Probiotics in the development and treatment of allergic disease

Gut microbiota composition can discriminate between allergic and healthy children, and the distinction may precede clinical manifestations of disease. The mother provides the first inoculum of bacteria, which influences the risk of becoming allergic later in life. Bifidobacterium species are major determinants of disease risk. Specific probiotics may modulate early microbial colonization, which represents the first intervention target in allergic disease, together with their ability to reverse the increased intestinal permeability characteristic of children with atopic eczema and food allergy. Probiotics also enhance gut-specific IgA responses, which are frequently defective in children with food allergy. In addition, probiotics have the potential to alleviate allergic inflammation locally and systemically.

Treatment of necrotizing enterocolitis with probiotics

Necrotizing enterocolitis (NEC) is a devastating condition characterized by diffuse intestinal inflammation and necrosis in preterm infants. It is the most common gastrointestinal emergency in the neonatal intensive care unit and is associated with significant morbidity and mortality. Primary risk factors include prematurity and low birth weight. Although the pathogenesis of NEC is complex and not entirely understood, it is known that an interplay between immature intestinal immune responses and the process of bacterial colonization is required for the development of this disease.

A commentary on the safety of probiotics

Probiotics have a long record of safety, which relates primarily to lactobacilli and bifidobacteria. Experience with other forms of probiotic is more limited. There is no such thing as zero risk, particularly in the context of certain forms of host susceptibility. There is poor public understanding of the concept of risk, in general, and risk/benefit analysis, in particular. Uncertainty persists regarding the potential for transfer of antibiotic resistance with probiotics, but the risk seems to be low with currently available probiotic products. As with other forms of therapeutics, the safety of probiotics should be considered on a strain-by-strain basis.

Time to recognize our fellow travellers

It is increasingly apparent that human health is reliant on our fellow travellers, the innumerable microorganisms that inhabit our bodies. This realization has led to the concept of the superorganism, which suggests that shared metabolic and signalling pathways are crucial for optimal existence of both host and commensal microflora. This commentary focuses on implications of this paradigm for personalized medicine and therapeutics. Study of the microbiome, the collection of microorganisms inhabiting the body, may identify disease-associated microbial profiles with pathophysiological and diagnostic value. As with genomics, companies will emerge offering direct to consumer microbiome analysis. Probiotics can potentially modulate the superorganism for therapeutic benefit. However, the probiotics industry will need to undergo a transformation, with increased focus on stringent manufacturing guidelines and high-quality clinical trials. Ultimately, we suggest that healthcare will move beyond its prevailing focus on human physiology, and embrace the superorganism as a paradigm to understand disease.

Probiotic bacteria in the prevention and the treatment of inflammatory bowel disease

Definitive curative strategies for inflammatory bowel disease remain challenging for physicians and patients. For decades, probiotic organisms have been used in various gastrointestinal diseases. Only recently has comprehension of the pathophysiology of inflammatory bowel disease developed to the point where the significance of the host gastrointestinal microbial population is seen to have marked influence on the initiation and ongoing inflammatory processes of Crohn disease and ulcerative colitis. Well-designed, large randomized controlled trials using probiotics in patients with inflammatory bowel disease are required for probiotics to become mainstream therapy.

Probiotics for human health -new innovations and emerging trends

The role of the gut microbiome in human health and disease with a particular emphasis on therapeutic use of probiotics under specific medical conditions was mainly highlighted in 1st Annual conference of Probiotic Association of India (PAi) and International Symposium on “Probiotics for Human Health - New Innovations and Emerging Trends” held on 27th-28th August, 2012 at New Delhi, India. There is increasing recognition of the fact that dysbiosis or alteration of this gut microbiome may be implicated in gastro-intestinal disorders including diarrheal diseases, ulcerative colitis, inflammatory bowel diseases, life style diseases viz. Diabetes Mellitus-2 and obesity etc. This report summarizes the proceedings of the conference and the symposium comprehensively. Although, research on probiotics has been continuing for the past few decades, the subject has been currently the major focus of attention across the world due to recent advances and new developments in genomics, transcriptomics, proteomics, metabolomics and emergence of new generation of high through put sequencing technologies that have immensely helped in understanding the probiotic functionality and mode of action from nutritional and health perspectives. There is now sufficient evidence backed up with good quality scientific clinical data to suggest that probiotic interventions could indeed be effective in various types of diarrheal diseases, other chronic gastrointestinal inflammatory disorders like pouchitis, necrotizing entero-colitis, allergic responses and lactose intolerance etc. This report makes a modest attempt to give all the stake holders involved in development of probiotic based functional/health foods an overview of the current status of probiotics research at the Global and National level. The most crucial issues that emerged from the lead talks delivered by the eminent speakers from India and abroad were the major focus of discussions in different plenary and technical sessions. By discussing some of these issues from scientific perspectives, the conference could achieve its prime objective of disseminating the current knowledge on the prospects of probiotics as potential biotherapeutics in the management of human health and diseases.

Adaptation of bifidobacteria to the gastrointestinal tract and functional consequences

Members of the genus Bifidobacterium are considered to be important constituents of the microbiota of animals, from insects to mammals. They are gut commensals extensively used by the food industry as probiotic microorganisms, since some strains have been shown to have specific beneficial effects. However, the molecular processes underlying their functional capacities to promote a healthy status in the host, as well as those involved in survival, colonization and persistence of bifidobacteria in the gut, are far from being completely understood. This review summarizes the current knowledge on the mechanisms used by bifidobacteria to cope with gastrointestinal factors and to adapt to them, and discusses the advantages of the adaptive traits acquired by these microorganisms as a consequence of their interactions with the gastrointestinal tract environment, as well as the impact of such adaptations in the functional characteristics of bifidobacteria.