Probiotics for the prevention of necrotising enterocolitis in very low-birth-weight infants: a meta-analysis and systematic review

Current Patterns of Probiotic Use in U.S. Neonatal Intensive Care Units: A Multi-Institution Survey

OBJECTIVE

Probiotic supplementation is associated with health benefits in preterm infants. The 2021 American Academy of Pediatrics (AAP) statement on probiotic use advised caution, citing heterogeneity and absence of federal regulation. We assessed the impact of the AAP statement and current institution-wide patterns of probiotic use across neonatal intensive care units (NICU) across the United States.

STUDY DESIGN

A cross-sectional web-based institutional survey using REDCap was emailed to 430 Children's Hospital Neonatal Consortium (CHNC) and Pediatrix Medical Group institutions. The survey captured data on probiotic formulations, supplementation, initiation and cessation criteria, reasons for discontinuation, interest in initiating, and AAP statement's impact.

RESULTS

Ninety-five (22.1%) hospitals, including 42/46 (91%) CHNC and 53/384 (14%) Pediatrix institutions, completed the survey. Thirty-seven (39%) currently use probiotics. Fourteen different probiotic formulations were reported. The common criteria for initiation were birth weight <1,500 g and gestational age <32 weeks. Parental consent or assent was obtained at only 30% of institutions. Five hospitals (11%) with prior probiotic use discontinued solely due to the AAP statement. Overall, 23 (24%) of hospitals indicated that the AAP statement significantly influenced their decision regarding probiotic use. Nineteen of 51 nonusers (37%) are considering initiation.

CONCLUSION

Probiotic use in preterm infants is likely increasing in NICUs across the United States, but significant variability exists. The 2021 AAP statement had variable impact on NICUs' decision regarding probiotic use. The growing interest in adopting probiotics and the significant interhospital variability highlight the need for better regulation and consensus guidelines to ensure standardized use.

KEY POINTS

· Probiotic use in preterm infants is likely increasing in U.S. NICUs, but clinical variability exists.. · The AAP statement on probiotic use in preterm infants had a modest impact on current practices.. · There's a need for better product regulation and consensus guidelines to ensure standardized use..

Probiotic supplementation and risk of necrotizing enterocolitis and mortality among extremely preterm infants-the Probiotics in Extreme Prematurity in Scandinavia (PEPS) trial: study protocol for a multicenter, double-blinded, placebo-controlled, and registry-based randomized controlled trial

BACKGROUND

Extremely preterm infants, defined as those born before 28 weeks' gestational age, are a very vulnerable patient group at high risk for adverse outcomes, such as necrotizing enterocolitis and death. Necrotizing enterocolitis is an inflammatory gastrointestinal disease with high incidence in this cohort and has severe implications on morbidity and mortality. Previous randomized controlled trials have shown reduced incidence of necrotizing enterocolitis among older preterm infants following probiotic supplementation. However, these trials were underpowered for extremely preterm infants, rendering evidence for probiotic supplementation in this population insufficient to date.

METHODS

The Probiotics in Extreme Prematurity in Scandinavia (PEPS) trial is a multicenter, double-blinded, placebo-controlled and registry-based randomized controlled trial conducted among extremely preterm infants (n = 1620) born at six tertiary neonatal units in Sweden and four units in Denmark. Enrolled infants will be allocated to receive either probiotic supplementation with ProPrems® (Bifidobacterium infantis, Bifidobacterium lactis, and Streptococcus thermophilus) diluted in 3 mL breastmilk or placebo (0.5 g maltodextrin powder) diluted in 3 mL breastmilk per day until gestational week 34. The primary composite outcome is incidence of necrotizing enterocolitis and/or mortality. Secondary outcomes include incidence of late-onset sepsis, length of hospitalization, use of antibiotics, feeding tolerance, growth, and body composition at age of full-term and 3 months corrected age after hospital discharge.

DISCUSSION

Current recommendations for probiotic supplementation in Sweden and Denmark do not include extremely preterm infants due to lack of evidence in this population. However, this young subgroup is notably the most at risk for experiencing adverse outcomes. This trial aims to investigate the effects of probiotic supplementation on necrotizing enterocolitis, death, and other relevant outcomes to provide sufficiently powered, high-quality evidence to inform probiotic supplementation guidelines in this population. The results could have implications for clinical practice both in Sweden and Denmark and worldwide.

TRIAL REGISTRATION

( Clinicaltrials.gov ): NCT05604846.

Neonatal outcomes following introduction of routine probiotic supplementation to very preterm infants

AIM

To evaluate the combined outcome of death and/or severe grade necrotising enterocolitis (NEC) in very preterm infants admitted to Cork University Maternity Hospital, Ireland, before and after introduction of routine supplementation with Bifidobacterium bifidum and Lactobacillus acidophilus probiotics (Infloran®).

METHODS

A retrospective study of infants <32 weeks gestation and < 1500 g surviving beyond 72 h of life was performed. Two 6-year epochs; pre-probiotics (Epoch 1: 2008-2013) and with probiotics (Epoch 2: 2015-2020), were evaluated. The primary outcome was defined as death after 72 h or NEC Bell stage 2a or greater.

RESULTS

Seven-hundred-and-forty-four infants were included (Epoch 1: 391, Epoch 2: 353). The primary outcome occurred in 67 infants (Epoch 1: 37, Epoch 2: 30, p = 0.646). After adjustment, the difference was significant (OR [95% CI]: 0.53 [0.29 to 0.97], p = 0.038). Differences between epochs did not depend on gestational age group (<28 weeks; ≥28 weeks).

CONCLUSION

There was an associated reduction of the composite outcome of severe grade NEC and/or death, after adjustment for confounding variables, with introduction of routine administration of a B. bifidum and L. acidophilus probiotic at our institution.

Effectiveness of a probiotic combination on the neurodevelopment of the very premature infant

Probiotics have shown a benefit in reducing necrotising enterocolitis in the premature infant, however the study of their effect on premature neonates' neurodevelopment is limited. The aim of our study was to elucidate whether the effect of Bifidobacterium bifidum NCDO 2203 combined with Lactobacillus acidophilus NCDO 1748 could positively impact the neurodevelopment of the preterm neonates. Quasi-experimental comparative study with a combined treatment of probiotics in premature infants < 32 weeks and < 1500 g birth weight, cared for at a level III neonatal unit. The probiotic combination was administered orally to neonates surviving beyond 7 days of life, until 34 weeks postmenstrual age or discharge. Globally, neurodevelopment was evaluated at 24 months corrected age. A total of 233 neonates were recruited, 109 in the probiotic group and 124 in the non-probiotic group. In those neonates receiving probiotics, there was a significant reduction in neurodevelopment impairment at 2 years of age RR 0.30 [0.16-0.58], and a reduction in the degree of impairment (normal-mild vs moderate-severe, RR 0.22 [0.07-0.73]). Additionally, there was a significant reduction in late-onset sepsis (RR 0.45 [0.21-0.99]). The prophylactic use of this probiotic combination contributed to improving neurodevelopmental outcome and reduced sepsis in neonates born at < 32 weeks and < 1500 g.Per style, a structured abstract is not allowed so we have changed the structured abstract to an unstructured abstract. Please check and confirm.Accepted.

Probiotics to prevent necrotizing enterocolitis and reduce mortality in neonates: A meta-analysis

BACKGROUND

Probiotics are gradually being used as a supplementation to prevent necrotizing enterocolitis (NEC) and reduce mortality in neonates. We performed an updated meta-analysis to systematically evaluate the efficacy and safety of prophylactic probiotic supplementation for preventing NEC.

METHODS

The databases including PubMed, Embase, Scopus, Web of Science, and China National Knowledge Infrastructure were used to search the relevant articles. The latest retrieval date was up to December 2021. The meta-analysis was performed using Stata version 10.0. Finally, a total of 70 studies containing 8319 cases and 9283 controls were included. The strength of the association between the supplementation of probiotics and NEC was measured by risk ratios (RRs) with 95% confidence intervals (CIs). Pooled effect sizes across studies were performed by a random effect model.

RESULTS

The results showed that the probiotics could significantly reduce the incidence of NEC (stage II or more) (RR = 0.436, 95% CI = 0.357-0.531, P < .001), the overall mortality (RR = 0.651, 95% CI = 0.506-0.836, P < .001), and NEC-related mortality (RR = 0.639, 95% CI = 0.423-0.966, P = .034). Due to the lack of sufficient sample size, we did not perform the subgroup analysis by types of probiotic strain.

CONCLUSION

This meta-analysis indicates that the use of probiotics can effectively reduce the occurrence of NEC and mortality in neonates.

Microbiome-targeting therapies in the neonatal intensive care unit: safety and efficacy

Microbiome-targeting therapies have received great attention as approaches to prevent disease in infants born preterm, but their safety and efficacy remain uncertain. Here we summarize the existing literature, focusing on recent meta-analyses and systematic reviews that evaluate the performance of probiotics, prebiotics, and/or synbiotics in clinical trials and studies, emphasizing interventions for which the primary or secondary outcomes were prevention of necrotizing enterocolitis, late-onset sepsis, feeding intolerance, and/or reduction in hospitalization length or all-cause mortality. Current evidence suggests that probiotics and prebiotics are largely safe but conclusions regarding their effectiveness in the neonatal intensive care unit have been mixed. To address this ambiguity, we evaluated publications that collectively support benefits of probiotics with moderate to high certainty evidence in a recent comprehensive network meta-analysis, highlighting limitations in these trials that make it difficult to support with confidence the routine, universal administration of probiotics to preterm infants.

Parents' Perspective on Probiotics in Preschool Children: A Cross-sectional Survey

Introduction

The composition of the human gut microbiota, which can also be regulated by the consumption of probiotics, has a significant impact on host health. The main source of probiotics can be foods such as fermented foods, yogurts, fermented drinks and/or probiotic supplements. While parents play a critical role in ensuring the well-being of their children, this cross-sectional study is focused on parents' perspectives regarding the use of probiotics in the preschool period.

Methods

The self-administered online survey consisted of 24 questions arranged across two thematic sections. The final data analysis included 102 parents (96% F; 4% M), aged between 22 and 47. Their children were aged up to 6 years.

Results

The majority (52%) of the parents were familiar with the term 'probiotics' and 86.3% were including probiotics in their children's diet at the time of the survey. The main source was probiotic food (36.3%), of which yoghurt was the most commonly consumed (87.2%). The inclusion of probiotic supplements in a child's diet was positively correlated with parents' consumption and level of knowledge about the term 'probiotics'. Digestive tract-related disorders were the most frequently reported motive for the initial introduction of probiotics into children's diet.

Conclusions

Based on our study results, parents are familiar with probiotics and include them in their children's diet. However, an attempt should be made to close the gaps in parents' knowledge that our research identified. Further studies are needed to determine the recommended amount of probiotic foods, as well as strategies to educate parents about the benefits of including probiotic foods in their children's diet.

Manipulating the neonatal gut microbiome: current understanding and future perspectives

The development of a healthy intestinal microbiome following birth contributes to the overall health of the infant during childhood and into adulthood. However, modern birth practices such as caesarean delivery, feeding, antibiotic exposure as well as maternal factors have the potential to greatly impact infant microbiome development. Aberrant microbiome development may be a key factor in the increasing incidence of inflammatory and gut diseases. This review will summarise the current understanding of how modern birth practices may contribute to deficiencies in neonatal gut microbiome development and will also present potential methods of microbiome engineering that aim to ensure the development of a healthy and robust microbiome to protect the host from disease throughout their life.

Next-Generation Probiotic Therapy to Protect the Intestines From Injury

Probiotics are live microorganisms that, when administered in adequate amounts, provide health benefits to the host. Some strains of the probiotic Lactobacillus reuteri (L. reuteri) have both antimicrobial and anti-inflammatory properties that may be exploited for the treatment and prevention of different gastrointestinal diseases, including necrotizing enterocolitis (NEC) and Clostridioides difficile (C. difficile) infection. Our laboratory has developed a new delivery system for L. reuteri in which the probiotic is incubated with biocompatible, semipermeable, porous dextranomer microspheres (DM) that can be loaded with beneficial and diffusible cargo. L. reuteri can be induced to form a biofilm by incubating the bacteria on the surface of these microspheres, which enhances the efficacy of the probiotic. Loading the DM with sucrose or maltose induces L. reuteri to produce more biofilm, further increasing the efficacy of the probiotic. Using a rat model of NEC, L. reuteri administered in its biofilm state significantly increases animal survival, reduces the incidence of NEC, preserves gut barrier function, and decreases intestinal inflammation. In a murine model of Clostridiodes difficile infection, L. reuteri administered in its biofilm state decreases colitis when administered either before or after C. difficile induction, demonstrating both prophylactic and therapeutic efficacy. There are currently no FDA-approved probiotic preparations for human use. An FDA-approved phase I clinical trial of L. reuteri in its biofilm state in healthy adults is currently underway. The results of this trial will be used to support a phase 1 clinical trial in neonates, with the goal of utilizing L. reuteri in its biofilm state to prevent NEC in premature neonates in the future.

Probiotic sepsis in preterm neonates-a systematic review

Sepsis due to the administered probiotic strain/s is a barrier against adoption of prophylactic probiotic supplementation in preterm infants to reduce the risk of necrotising enterocolitis (NEC ≥ Stage II), all-cause mortality, late-onset sepsis, and feeding intolerance. We aimed to conduct a systematic review for reports of probiotic sepsis in preterm infants (gestation < 37 weeks). Databases including PubMed, Embase, Emcare, Cochrane Central library, and Google Scholar were searched in August 2021 and updated in Jan 2022. Probiotic sepsis was defined as positive blood/CSF culture isolating administered probiotic strain with symptoms suggestive of infection. Data collection included birth weight, gestation, comorbidities (e.g. gut surgery, NEC), presence of central venous catheters, treatment, and outcome. Literature search revealed 1569 studies. A total of 16 reports [randomised control trial (RCT): none; non-RCT: 1; case series: 8; case report: 7] involving 32 preterm infants with probiotic sepsis were included after exclusions for various reasons. Majority of the cases were born < 32 weeks' gestation. Bifidobacterium (N = 19) was the most commonly isolated organism followed by Lactobacillus (N = 10), and Saccharomyces (N = 3). A total of 25/32 cases were confirmed to be due to the administered probiotic strain on full genomic analysis. Two studies reported one neonatal death each. Twelve neonates had comorbidities. Majority were treated with antibiotics (29/32) whereas others (3/32) required antifungal treatment.

CONCLUSION

Probiotics sepsis is relatively an uncommon event in preterm infants. Majority of the cases recovered after antibiotic or antifungal treatment. The importance of optimal surveillance and treatment of probiotic sepsis and research towards alternatives to probiotics (e.g. postbiotics) is emphasised.

WHAT IS KNOWN

• Probiotics have been shown to reduce necrotising enterocolitis, late-onset sepsis, all-cause mortality, and time to reach full enteral feeds in preterm infants. • Despite the evidence, use of probiotics is not universal due to concerns regarding probiotic-associated sepsis in preterm infants.

WHAT IS NEW

• This comprehensive systematic review showed that probiotic sepsis is a relatively rare phenomenon in preterm infants. • All except one case where the diagnosis was uncertain recovered after antimicrobial therapy.

Exploring the long-term colonisation and persistence of probiotic-prophylaxis species on the gut microbiome of preterm infants: a pilot study

Preterm infants suffer from a higher incidence of acute diseases such as necrotising enterocolitis and sepsis. This risk can be mitigated through probiotic prophylaxis during admission. This reduction in risk is likely the result of acute modulation of the gut microbiome induced by probiotic species, which has been observed to occur up until discharge. We aimed to determine if this modulation, and the associated probiotic species, persisted beyond discharge. We conducted both a cross-sectional analysis (n = 18), at ~ 18 months of age, and a longitudinal analysis (n = 6), from admission to 18 months of the gut microbiome of preterm infants using both shotgun metagenomics and 16S rRNA profiling respectively. The 16S amplicon sequencing revealed that the microbial composition of the probiotic-supplemented infants changed dramatically over time, stabilising at discharge. However, species from the probiotic Infloran^®, as well as positive modulatory effects previously associated with supplementation, do not appear to persist beyond discharge and once prophylaxis has stopped.    Conclusions: Although differences exist between supplemented and non-supplemented groups, the implications of these differences remain unclear. Additionally, despite a lack of long-term colonisation, the presence of probiotics during early neonatal life may still have modulatory effects on the microbiome assembly and immune system training. What is Known: • Evidence suggests modulation of the microbiome occurs during probiotic prophylaxis, which may support key taxa that exert positive immunological benefits. • Some evidence suggests that this modulation can persist post-prophylaxis. What is New: • We present support for long-term modulation in association with probiotic prophylaxis in a cohort of infants from North Queensland Australia. • We also observed limited persistence of the probiotic species post-discharge.

Risk factors for hyperglycemia in extremely low birth weight infants during the first 14 days

BACKGROUND

There are limited data regarding the risk factors for hyperglycemia in extremely low birth weight infants (ELBWIs). The aim of this observational study was to investigate the incidence of hyperglycemia among ELBWIs during the first 14 days of life and identify independent risk factors for hyperglycemia development.

METHODS

We retrospectively evaluated 55 ELBWIs (32 male infants) between January 2015 and March 2020. Hyperglycemia was diagnosed when the glucose level was ≥180 mg/dL. Demographic and clinical data were extracted from the patients' medical records. The risk factors associated with the onset of hyperglycemia were identified by Cox proportional hazards regression analysis with variables that had previously been identified as risk factors for hyperglycemia.

RESULTS

Hyperglycemia developed in 23 patients (41.8%) within the first 14 days of life. Gestational age, chorioamnionitis, postnatal intravenous glucocorticoids, and probiotic type were included in the analysis. The results indicated that hyperglycemia was significantly associated with gestational age (hazard ratio [HR], 0.65; 95% confidence interval [CI], 0.48-0.87; P = 0.004). Further, Bifidobacterium breve (B. breve M-16V) use was related to hyperglycemia in ELBWIs (HR, 2.95; 95% CI, 1.10-7.87; P = 0.031).

CONCLUSION

Hyperglycemia was strongly associated with lower gestational age and B. breve M-16V use in our study population. Although probiotic supplementation may be beneficial for preterm infants to reduce the incidence of necrotizing enterocolitis, the dextrin used as an excipient in B. breve M-16V may lead to an undesirable carbohydrate load in ELBWIs.

To Probiotic or Not to Probiotic: A Metagenomic Comparison of the Discharge Gut Microbiome of Infants Supplemented With Probiotics in NICU and Those Who Are Not

BACKGROUND

Preterm birth is associated with the development of both acute and chronic disease, and the disruption of normal gut microbiome development. Recent studies have sought to both characterize and understand the links between disease and the microbiome. Probiotic treatment may correct for these microbial imbalances and, in turn, mitigate disease. However, the criteria for probiotic supplementation in NICU's in North Queensland, Australia limits its usage to the most premature (<32 weeks gestation) and small for gestational age infants (<1,500 g). Here we use a combination of amplicon and shotgun metagenomic sequencing to compare the gut microbiome of infants who fulfill the criteria for probiotic-treatment and those who do not. The aims of this study were to determine if probiotic-supplemented preterm infants have significantly different taxonomic and functional profiles when compared to non-supplemented preterm infants at discharge.

METHODS

Preterm infants were recruited in North Queensland, Australia, with fecal samples collected just prior to discharge (36 ± 0.5 weeks gestation), to capture potential changes that could be probiotic induced. All samples underwent 16S rRNA gene amplicon sequencing, with a subset also used for shotgun metagenomics. Mixed effects models were used to assess the effect of probiotics on alpha diversity, beta diversity and taxonomic abundance, whilst accounting for other known covariates.

RESULTS

Mixed effects modeling demonstrated that probiotic treatment had a significant effect on overall community composition (beta diversity), characterized by greater alpha diversity and differing abundances of several taxa, including Bifidobacterium and Lactobacillus, in supplemented infants.

CONCLUSION

Late preterm-infants who go without probiotic-supplementation may be missing out on stabilizing-effects provided through increased alpha diversity and the presence of commensal microbes, via the use of probiotic-treatment. These findings suggest that late-preterm infants may benefit from probiotic supplementation. More research is needed to both understand the consequences of the differences observed and the long-term effects of this probiotic-treatment.

Clinical implications of preterm infant gut microbiome development

Perturbations to the infant gut microbiome during the first weeks to months of life affect growth, development and health. In particular, assembly of an altered intestinal microbiota during infant development results in an increased risk of immune and metabolic diseases that can persist into childhood and potentially into adulthood. Most research into gut microbiome development has focused on full-term babies, but health-related outcomes are also important for preterm babies. The systemic physiological immaturity of very preterm gestation babies (born earlier than 32 weeks gestation) results in numerous other microbiome-organ interactions, the mechanisms of which have yet to be fully elucidated or in some cases even considered. In this Perspective, we compare assembly of the intestinal microbiome in preterm and term infants. We focus in particular on the clinical implications of preterm infant gut microbiome composition and discuss the prospects for microbiome diagnostics and interventions to improve the health of preterm babies.

Empirical Antimicrobial Therapy of Neonates with Necrotizing Enterocolitis: A Systematic Review

OBJECTIVE

 Necrotizing enterocolitis (NEC) is an inflammatory disease of the gastrointestinal tract characterized by ischemic necrosis of the intestinal mucosa, mostly affecting premature neonates. Management of NEC includes medical care and surgical approaches, with supportive care and empirical antibiotic therapy recommended to avoid any disease progression. However, there is still no clear evidence-based consensus on empiric antibiotic strategies or surgical timing. This study was aimed to review the available evidence on the effectiveness and safety of different antibiotic regimens for NEC.

STUDY DESIGN

 MEDLINE, EMBASE, Cochrane CENTRAL, and CINAHL databases were systematically searched through May 31, 2020. Randomized controlled trials (RCTs) and nonrandomized interventions reporting data on predefined outcomes related to NEC treatments were included. Clinical trials were assessed using the criteria and standard methods of the Cochrane risk of bias tool for randomized trials, while the risk of bias in nonrandomized studies of interventions was evaluated using the ROBINS-I tool. The certainty in evidence of each outcome's effects was assessed using the Grading of Recommendations Assessment, Development, and Evaluation approach.

RESULTS

 Five studies were included in this review, two RCTs and three observational studies, for a total amount of 3,161 patients. One RCT compared the outcomes of parenteral (ampicillin plus gentamicin) and oral (gentamicin) treatment with parenteral only. Three studies (one RCT and two observational) evaluated adding anaerobic coverage to different parenteral regimens. The last observational study compared two different parenteral antibiotic combinations (ampicillin and gentamicin vs. cefotaxime and vancomycin).

CONCLUSION

 No antimicrobial regimen has been shown to be superior to ampicillin and gentamicin in decreasing mortality and preventing clinical deterioration in NEC. The use of additional antibiotics providing anaerobic coverage, typically metronidazole, or use of other broad-spectrum regimens as first-line empiric therapy is not supported by the very limited current evidence. Well-conducted, appropriately sized comparative trials are needed to make evidence-based recommendations.

KEY POINTS

· Ampicillin and gentamicin are effective in decreasing mortality and preventing clinical deterioration in NEC.. · Metronidazole could be added in patients with surgical NEC.. · No study with high-quality evidence was found..

Lactobacillus reuteri Colonisation of Extremely Preterm Infants in a Randomised Placebo-Controlled Trial

Lactobacillus reuteri DSM 17938 supplementation reduces morbidities in very low birth weight infants (<1500 g), while the effect on extremely low birth weight infants (ELBW, <1000 g) is still questioned. In a randomised placebo-controlled trial (ClinicalTrials.gov ID NCT01603368), head growth, but not feeding tolerance or morbidities, improved in L. reuteri-supplemented preterm ELBW infants. Here, we investigate colonisation with the probiotic strain in preterm ELBW infants who received L. reuteri DSM 17938 or a placebo from birth to postmenstrual week (PMW) 36. Quantitative PCR was used on 582 faecal DNA samples collected from 132 ELBW infants at one, two, three, and four weeks, at PMW 36, and at two years of age. Human milk oligosaccharides were measured in 31 milk samples at two weeks postpartum. At least 86% of the ELBW infants in the L. reuteri group were colonised with the probiotic strain during the neonatal period, despite low gestational age, high antibiotic pressure, and independent of infant feeding mode. Higher concentrations of lacto-N-tetraose, sialyl-lacto-N-neotetraose c, and 6′-sialyllactose in mother’s milk weakly correlated with lower L. reuteri abundance. Within the L. reuteri group, higher L. reuteri abundance weakly correlated with a shorter time to reach full enteral feeding. Female sex and L. reuteri colonisation improved head growth from birth to four weeks of age. In conclusion, L. reuteri DSM 17938 supplementation leads to successful colonisation in ELBW infants.

Effects of Lactobacillus reuteri supplementation on the gut microbiota in extremely preterm infants in a randomized placebo-controlled trial

Extremely low birth weight (ELBW) infants often develop an altered gut microbiota composition, which is related to clinical complications, such as necrotizing enterocolitis and sepsis. Probiotic supplementation may reduce these complications, and modulation of the gut microbiome is a potential mechanism underlying the probiotic effectiveness. In a randomized, double-blind, placebo-controlled trial, we assessed the effect of Lactobacillus reuteri supplementation, from birth to post-menstrual week (PMW)36, on infant gut microbiota. We performed 16S amplicon sequencing in 558 stool samples from 132 ELBW preterm infants at 1 week, 2 weeks, 3 weeks, 4 weeks, PMW36, and 2 years. Probiotic supplementation results in increased bacterial diversity and increased L. reuteri abundance during the 1^st month. At 1 week, probiotic supplementation also results in a lower abundance of Enterobacteriaceae and Staphylococcaceae. No effects were found at 2 years. In conclusion, probiotics may exert benefits by modulating the gut microbiota composition during the 1^st month in ELBW infants.

L. reuteri DSM 17938 dominates the microbiota in supplemented ELBW infants

Supplemented ELBW infants have higher gut microbiota richness and diversity

Supplemented infants have lower abundance of Enterobacteriaceae and Staphylococcaceae

No effects of probiotic supplementation on the gut microbiota at PMW36 and 2 years

Prophylactic Probiotic Supplementation for Preterm Neonates-A Systematic Review and Meta-Analysis of Nonrandomized Studies

Systematic review and meta-analyses of randomized controlled trials (RCTs) show that probiotics reduce the risk of necrotizing enterocolitis (NEC ≥ Stage II), late onset sepsis (LOS), all-cause mortality, and feeding intolerance in preterm neonates. Data from observational studies is important to confirm probiotic effects in clinical practice. We aimed to compare outcomes before and after implementing routine probiotic supplementation (RPS) in preterm neonates (<37 weeks of gestation) by performing a systematic review of non-RCTs using Cochrane methodology. Databases including PubMed, The Cumulative Index to Nursing and Allied Health Literature (CINAHL), Embase, Cochrane Central library, and Google Scholar were searched in May 2020. A meta-analysis was performed using a random effects model. Categorical measure of effect size was expressed as OR and 95% CI. Statistical heterogeneity was assessed by the chi-squared test, I2 statistic. The level of evidence (LOE) was summarized using GRADE (Grading of Recommendations Assessment, Development, and Evaluation) guidelines. Primary outcomes were NEC ≥ Stage II, LOS, and all-cause mortality. Secondary outcomes included probiotic sepsis. Thirty good-quality non-RCTs (n = 77,018) from 18 countries were included. The meta-analysis showed RPS was associated with significantly reduced: 1) NEC ≥ Stage II (30 studies, n = 77,018; OR: 0.60; 95% CI: 0.50, 0.73; P <0.00001, I2: 65%; LOE: Moderate), 2) LOS: (21 studies, n = 65,858; OR: 0.85; 95% CI: 0.74, 0.97; P = 0.02, I2: 74%; LOE: Low), and 3) all-cause mortality (27 non-RCTs, n = 70,977; OR: 0.77; 95% CI: 0.68, 0.88; P = 0.0001, I2: 49%; LOE: Low). Subgroups: 1) extremely low birth weight (ELBW: birth weight <1000 g) neonates: RPS was associated with significantly reduced NEC ≥ Stage II (4.5% compared with 7.9%). However, there was no difference in LOS and mortality. 2) Multistrain RPS was more effective than single strain. One study reported 3 nonfatal cases of probiotic sepsis. In summary, moderate- to low-quality evidence indicates that RPS was associated with significantly reduced NEC ≥ Stage II, LOS, and all-cause mortality in neonates <37 weeks of gestation and NEC ≥ Stage II in ELBW neonates.

Probiotics for Preventing Necrotizing Enterocolitis in Preterm Infants: A Network Meta-Analysis

BACKGROUND

Recent evidence supports a role of probiotics in preventing necrotizing enterocolitis (NEC) in preterm infants.

METHODS

A systematic review and network meta-analysis of randomized controlled trials (RCTs) on the role of probiotics in preventing NEC in preterm infants, focusing on the differential effect of type of feeding, was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A random-effects model was used; a subgroup analysis on exclusively human milk (HM)-fed infants vs. infants receiving formula (alone or with HM) was performed.

RESULTS

Fifty-one trials were included (10,664 infants, 29 probiotic interventions); 31 studies (19 different probiotic regimens) were suitable for subgroup analysis according to feeding. In the overall analysis, Lactobacillus acidophilus LB revealed the most promising effect for reducing NEC risk (odds ratio (OR), 0.03; 95% credible intervals (CrIs), 0.00-0.21). The subgroup analysis showed that Bifidobacterium lactis Bb-12/B94 was associated with a reduced risk of NEC stage ≥2 in both feeding type populations, with a discrepancy in the relative effect size in favour of exclusively HM-fed infants (OR 0.04; 95% CrIs <0.01-0.49 vs. OR 0.32; 95% CrIs 0.10-0.36).

CONCLUSIONS

B. lactis Bb-12/B94 could reduce NEC risk with a different size effect according to feeding type. Of note, most probiotic strains are evaluated in few trials and relatively small populations, and outcome data according to feeding type are not available for all RCTs. Further trials are needed to confirm the present findings.

Evidence-Based Practices Reduce Necrotizing Enterocolitis and Improve Nutrition Outcomes in Very Low-Birth-Weight Infants

BACKGROUND

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in preterm infants. Survivors may suffer both short- and long-term morbidities. Current evidence suggests that the incidence of NEC can be reduced by standardizing the care delivery in addressing key risk factors including an altered gut microbiome, use of formula milk, hyperosmolar feeds, and unrestricted use of high-risk medications METHODS: Since 2014, the department has a workgroup who analyzed all cases of NEC within a month of diagnosis to identify preventable risk factors. Existing evidence-based quality improvement strategies were revised and new ones were implemented sequentially over the next 4 years. These strategies include (1) a standardized feeding protocol, (2) early initiation of enteral feeding using human milk, (3) optimization of the osmolality of preterm milk feeds using standardized dilution guidelines for additives, and (4) promotion of healthy microbiome by use of probiotics, early oral care with colostrum and by restricting high-risk medications and prolonged use of empirical antibiotics RESULTS: Baseline characteristics of the patients including sex, gestational age, and birth weight were similar during the study period. After implementing the evidence-based practices successively over 4 years, the incidence of NEC in very- low birth-weight (VLBW) infants dropped from 7% in 2014 to 0% (P < .001) in 2018. The duration of parenteral nutrition, use of central line, and days to full feeds were also reduced significantly (P < .05) CONCLUSION: Adopting evidence-based best practices resulted in a significant decrease in the incidence of NEC and improved the nutrition outcomes in VLBW infants.

Probiotics and Human Milk Oligosaccharides in Premature Infants

Intestinal dysbiosis precedes and is a likely causative factor in necrotizing enterocolitis (NEC) and many cases of late-onset sepsis. Randomized controlled trials and observational cohort studies demonstrate decreased risk of NEC, sepsis, and death with the administration of probiotic microbes and decreased risk of NEC and sepsis with feeding of human milk. Animal studies suggest promising mechanisms by which probiotic microbes and human milk oligosaccharides alter the composition of the intestinal microbiota and may prevent disease in premature infants. Inclusion of parents in discussions of the risks and benefits of human milk and probiotics for premature infants is essential.

Does probiotic bacteremia in premature infants impact clinically relevant outcomes? A case report and updated review of literature

Prophylactic use of probiotics decreases the incidence of necrotizing enterocolitis (NEC) in premature infants. However, there are ongoing concerns related to the routine use of probiotics including inconsistent literature regarding optimal dose and strain, lack of regulatory standards in production and reports regarding potential side effects. There is limited data regarding the incidence of probiotic bacteremia and its impact on relevant clinical outcomes in the premature population. We report the first case of Bifidobacterium longum bacteremia in our center since the routine introduction of probiotics. The neonate had NEC with perforation on day of life 7, which likely led to translocation of the probiotic strain to the blood stream. The neonate did not have any hemodynamic instability and the repeat blood culture was negative after starting antibiotic therapy. We also conducted a literature review and found 13 other cases of probiotic bacteremia in premature or very low birth weight neonates. Although the incidence of probiotic bacteremia is low, it can impact several clinical outcomes including prolonged exposure to antibiotics, removal of central lines and additional laboratory testing such as lumbar puncture. There has been no mortality attributable to probiotic bacteremia and there is no data regarding long term neurodevelopmental outcomes.

Targeting Gut Microbial Biofilms-A Key to Hinder Colon Carcinogenesis?

Colorectal cancer (CRC) is a global public health issue which poses a substantial humanistic and economic burden on patients, healthcare systems and society. In recent years, intestinal dysbiosis has been suggested to be involved in the pathogenesis of CRC, with specific pathogens exhibiting oncogenic potentials such as Fusobacterium nucleatum, Escherichia coli and enterotoxigenic Bacteroides fragilis having been found to contribute to CRC development. More recently, it has been shown that initiation of CRC development by these microorganisms requires the formation of biofilms. Gut microbial biofilm forms in the inner colonic mucus layer and is composed of polymicrobial communities. Biofilm results in the redistribution of colonic epithelial cell E-cadherin, increases permeability of the gut and causes a loss of function of the intestinal barrier, all of which enhance intestinal dysbiosis. This literature review aims to compile the various strategies that target these pathogenic biofilms and could potentially play a role in the prevention of CRC. We explore the potential use of natural products, silver nanoparticles, upconverting nanoparticles, thiosalicylate complexes, anti-rheumatic agent (Auranofin), probiotics and quorum-sensing inhibitors as strategies to hinder colon carcinogenesis via targeting colon-associated biofilms.

Grading the evidence to identify strategies to modify risk for necrotizing enterocolitis

Although risk for necrotizing enterocolitis (NEC) is often presented from the perspective of a premature infant's vulnerability to nonmodifiable risk factors, in this paper we describe the evidence and present recommendations to manage modifiable risks that are amenable to clinical actions. Using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria, we present recommendations in the context of their supporting evidence in a way that balances risks (e.g. potential harm, cost) and benefits. Across the prenatal, intrapartum, early and late clinical course, strategies to limit NEC risk in premature infants are presented. Our goal is to summarize modifiable NEC risk factors, grade the evidence to offer quality improvement (QI) targets for healthcare teams and offer a patient-family advocate's perspective on how to engage parents to recognize and reduce NEC risk.

Probiotics and Preterm Infants: A Position Paper by the European Society for Paediatric Gastroenterology Hepatology and Nutrition Committee on Nutrition and the European Society for Paediatric Gastroenterology Hepatology and Nutrition Working Group for Probiotics and Prebiotics

More than 10,000 preterm infants have participated in randomised controlled trials on probiotics worldwide, suggesting that probiotics in general could reduce rates of necrotising enterocolitis (NEC), sepsis, and mortality. Answers to relevant clinical questions as to which strain to use, at what dosage, and how long to supplement are, however, not available. On the other hand, an increasing number of commercial products containing probiotics are available from sometimes suboptimal quality. Also, a large number of units around the world are routinely offering probiotic supplementation as the standard of care despite lacking solid evidence. Our recent network meta-analysis identified probiotic strains with greatest efficacy regarding relevant clinical outcomes for preterm neonates. Efficacy in reducing mortality and morbidity was found for only a minority of the studied strains or combinations. In the present position paper, we aim to provide advice, which specific strains might potentially be used and which strains should not be used. In addition, we aim to address safety issues of probiotic supplementation to preterm infants, who have reduced immunological capacities and occasional indwelling catheters. For example, quality reassurance of the probiotic product is essential, probiotic strains should be devoid of transferable antibiotic resistance genes, and local microbiologists should be able to routinely detect probiotic sepsis. Provided all safety issues are met, there is currently a conditional recommendation (with low certainty of evidence) to provide either Lactobacillus rhamnosus GG ATCC53103 or the combination of Bifidobacterium infantis Bb-02, Bifidobacterium lactis Bb-12, and Streptococcus thermophilus TH-4 in order to reduce NEC rates.

Nutritional interventions to reduce rates of infection, necrotizing enterocolitis and mortality in very preterm infants

Observational studies demonstrating reduced rates of infections, necrotizing enterocolitis (NEC), and mortality in preterm infants fed their own mother's milk, as opposed to formula, have prompted endeavors to achieve similar effects with the right choice of food and food additives. In a systematic review of meta-analyses and randomized controlled trials (RCTs), we considered nutritional interventions aimed at reducing the rates of infections, NEC, or mortality in very preterm infants. The overall effects of particular interventions were presented as risk ratios with 95% confidence intervals. In RCTs, pasteurized human donor milk, as opposed to formula, reduced NEC but not infections or mortality. No differences emerged between infants receiving human or bovine milk-based fortifiers. Pooled data of small trials and a recent large RCT suggested that bovine lactoferrin reduced rates of fungal sepsis without impact on other infections, NEC, or mortality. Pooled data of RCTs assessing the use of prebiotic oligosaccharides found reduced infection but not mortality. Enteral L-glutamine (six RCTs) lowered infection rates, and enteral L-arginine (three RCTs) reduced NEC. A meta-analysis sensitivity approach found multiple-strain (but not single-strain) probiotics to be highly effective in reducing NEC and mortality. Thus, selected food components may help to improve outcomes in preterm infants.

Incidence, Treatment, and Outcome Trends of Necrotizing Enterocolitis in Preterm Infants: A Multicenter Cohort Study

Background: Data regarding the incidence and mortality of necrotizing enterocolitis trends are scarce in the literature. Recently, some preventive strategies have been confirmed (probiotics) or increased (breastfeeding rate). This study aims to describe the trends of necrotizing enterocolitis incidence, treatment, and mortality over the last decade in Spain. Methods: Multicenter cohort study with data from the Spanish Neonatal Network-SEN1500 database. The study period comprised from January 2005 to December 2017. Preterm infants <32 weeks of gestational age at birth without major congenital malformations were included for analysis. The main study outcomes were necrotizing enterocolitis incidence, co-morbidity (bronchopulmonary dysplasia, late-onset sepsis, cystic periventricular leukomalacia, retinopathy of prematurity, acute kidney injury), mortality, and surgical/non-surgical treatment. Results: Among the 25,821 included infants, NEC incidence was 8.8% during the whole study period and remained stable when comparing 4-year subperiods. However, more cases were surgically treated (from 48.8% in 2005-2008 to 70.2% in 2015-2017, p < 0.001). Mortality improved from 36.7% in the 2005-2008 to 26.6% in 2015-2017 (p < 0.001). Breastfeeding rates improved over the studied years (24.3% to 40.5%, p < 0.001), while gestational age remained invariable (28.5 weeks, p = 0.20). Prophylactic probiotics were implemented during the study period in some units, reaching 18.6% of the patients in 2015-2017. Conclusions: The incidence of necrotizing enterocolitis remained stable despite the improvement regarding protective factors frequency. Surgical treatment became more frequent over the study period, whereas mortality decreased.

Implementation of a probiotic protocol to reduce rates of necrotizing enterocolitis

OBJECTIVE

To utilize a probiotic protocol to achieve a 50% reduction in rates of necrotizing enterocolitis (NEC) ≥ Bell Stage 2 within 2 years of protocol implementation.

STUDY DESIGN

Literature review guided probiotic selection and protocol design. A driver diagram identified key drivers to achieve our aim. A U chart followed monthly NEC ≥ Bell Stage 2 per 100 patient days and per monthly admissions. The process measure was protocol compliance and the balancing measure was probiotic sepsis.

RESULTS

NEC ≥ Bell Stage 2 decreased from 0.14 to 0.04 per 100 patient days in infants < 33 weeks gestation or <1500 g, or a yearly rate of 7-2%. Protocol compliance was 98% and there were no cases of probiotic sepsis.

CONCLUSION

Implementation of a probiotic protocol was associated with a decrease in rates of NEC.

Historical aspects of probiotic use to prevent necrotising enterocolitis in preterm babies

Over the last few decades, numerous studies have evaluated probiotic use for the prevention of necrotising enterocolitis in preterm babies. Early 'proof of concept' studies evaluating whether probiotics are capable of colonising the preterm gut have translated into multiple observational studies, small and large randomised controlled trials. Some show evidence of benefit while others have produced disappointing results. In this paper, we review the history of probiotic use in preterm babies for NEC prevention in an attempt to explain why uncertainty exists and why this intervention has not been universally adopted into routine neonatal practice.

To start or not: Factors to consider when implementing routine probiotic use in the NICU

Supplementation of probiotics to very low birth weight (VLBW) infants has been extensively studied, with multiple meta-analyses reporting probiotics decrease the risk of necrotizing enterocolitis (NEC) and death. Despite availability of this evidence, the decision to initiate routine probiotic supplementation to preterm infants continues to be a complex one. There are uncertainties regarding the use of probiotics, including selecting the appropriate product, dose and target population. Additionally, availability of specific probiotic products and regulatory oversight varies by country, raising concerns regarding the safety and efficacy of specific probiotic products. In this review, we summarize the latest evidence on probiotic use in preterm infants and discuss considerations that may help guide clinicians who are considering routine probiotic supplementation.

The future of probiotics in the preterm infant

Probiotic administration to preterm infants is not universal despite randomised trial data from >10,000 infants, significant observational data and multiple meta-analyses. Advocates point to reductions in necrotising enterocolitis and sepsis, 'sceptics' hold concerns over data quality/interpretation or risks. Issues revolve around different products, primary outcomes, uncertain dosing strategies and individual large 'negative' trials alongside probiotic associated sepsis and quality control concerns. We review concerns and how to move probiotic use forward. Surprisingly little is known about parental perspectives, vital to inform next steps. How to share information and decisions around probiotic use now, and how this impacts on future available strategies is discussed. We address placebo controlled trials and propose alternate designs, including head to head studies, using 'routine' data collection systems, opt out consents and 'learning technologies' embedded in health care systems. We also raise the importance of underpinning mechanistic work to inform future trials.

Probiotics may not prevent the deterioration of necrotizing enterocolitis from stage I to II/III

BACKGROUND

Probiotic therapy can reduce the incidence of NEC. Therapeutic use of probiotics after NEC diagnosis reduces the severity of NEC in preterm infants or full-term infants is unclear. To evaluate the effect of probiotics on preventing the deterioration of necrotizing enterocolitis (NEC) from stage I to II/III.

METHODS

A retrospective matched cohort study was performed. Included patients were ultimately divided into two groups: the probiotic treatment group (probiotics were used ≥4 days) and the no probiotic treatment group. The differences in deterioration trends between the two groups were compared. Additionally, the risk factors associated with the deterioration of NEC were further analyzed with a case-control study.

RESULTS

A total of 231 infants met the inclusion criteria. Eighty-one pairs were matched according to similar gestational age and birth weight. Before matching, we found that the rate of deterioration of NEC from stage I to II/III in the group with probiotic treatment was similar to that in the group without probiotic treatment (23.1% [25/108] vs 26.0% [32/123], P = 0.614). After matching, the rate of deterioration of NEC between the two groups still had no significant difference (21.0% [17/81] vs 27.2% [22/81], P = 0.358). Logistic regression analysis showed that sepsis after NEC was an independent risk factor for NEC deteriorating from stage I to II/III (OR 2.378, 95% CI 1.005-5.628, P = 0.049).

CONCLUSION

Probiotics may not prevent the deterioration of NEC from stage I to II/III in infants, but this conclusion should be treated with caution.

Dysbiosis and Prematurity: Is There a Role for Probiotics?

Healthy microbiota is a critical mediator in maintaining health and it is supposed that dysbiosis could have a role in the pathogenesis of a number of diseases. Evidence supports the hypothesis that maternal dysbiosis could act as a trigger for preterm birth; aberrant colonization of preterm infant gut might have a role in feeding intolerance and pathogenesis of necrotizing enterocolitis. Despite several clinical trials and meta-analyses, it is still not clear if modulation of maternal and neonatal microbiota with probiotic supplementation decreases the risk of preterm birth and its complications.

New insights into necrotizing enterocolitis: From laboratory observation to personalized prevention and treatment

BACKGROUND/PURPOSE

Necrotizing enterocolitis (NEC) is a devastating disease of prematurity that develops after feeding, often without warning, and results in diffuse intestinal necrosis leading to sepsis and death in many cases. The lack of improvement in overall survival is influenced by nonspecific diagnostic modalities as well as inexact and nonpersonalized treatment strategies.

METHODS/RESULTS

Recently, we and others have shown that NEC develops in response to exaggerated bacterial signaling in the premature intestine, as a consequence of elevated expression and activity of the bacterial receptor toll-like receptor 4 (TLR4), which is important for normal gut development. Breast milk is a powerful TLR4 inhibitor, while mutations in TLR4 genes lead to increased NEC risk in humans, providing proof-of-concept for its role in NEC. Recently, a drug discovery approach has revealed a novel class of TLR4 inhibitors which are being developed for personalized approaches to NEC treatment.

CONCLUSION

This review will highlight the current understanding of the role of bacterial signaling in NEC pathogenesis, and will describe advances in diagnosis, prevention and treatment of NEC that may hopefully improve survival for these most fragile patients.

SYSTEMATIC REVIEW

Level of Evidence: Level II.

Probiotics and the prevention of necrotizing enterocolitis

BACKGROUND

Immaturity of the host immune system and alterations in the intestinal microbiome appear to be key factors in the pathogenesis of necrotizing enterocolitis (NEC). The aim of this paper is to weigh the evidence for the use of probiotics to prevent NEC in premature infants.

METHODS

Animal studies, randomized controlled trials, observational cohort studies and meta-analyses involving administration of probiotic products for the prevention of NEC were reviewed. This review of the evidence summarizes the available preclinical and clinical data.

RESULTS

In animal models probiotic microbes alter the intestinal microbiome, decrease inflammation and intestinal permeability and decrease the incidence and severity of experimental NEC. In randomized, placebo-controlled trials and cohort studies of premature infants, probiotic microbes decrease the risk of NEC, death and sepsis.

CONCLUSION

Evidence is strong for the prevention of NEC with the use of combination probiotics in premature infants who receive breast milk. The potential risks and benefits of probiotic administration to premature infants should be carefully reviewed with parents.

TYPE OF STUDY

Therapeutic.

LEVEL OF EVIDENCE

I.

Probiotics for preterm infants - time to end all controversies

Mortality, necrotising enterocolitis (NEC), late onset sepsis (LOS) and feeding intolerance are significant issues for very preterm (< 32 weeks) and extremely preterm (< 28 weeks) infants. The complications of ≥ Stage II NEC [e.g. Resection of the gangrenous gut, survival with intestinal failure, recurrent infections, prolonged hospital stay, and long-term neurodevelopmental impairment (NDI)] impose a significant health burden. LOS also carries significant burden including long-term NDI due to adverse effects of inflammation on the preterm brain during the critical phase of development. Frequent stopping of feeds due to feeding intolerance is a significant iatrogenic contributor to postnatal growth failure in extremely preterm infants. Over 25 systematic reviews and meta-analyses of RCTs (~12 000 participants) have reported that probiotics significantly reduce the risk of all-cause mortality, NEC ≥ Stage II, LOS and feeding intolerance in preterm infants. Systematic reviews and meta-analysis of non-RCTs have also shown that the benefits after adopting probiotics as a standard prophylaxis for preterm infants are similar to those reported in RCTs. No intervention comes close to probiotics when it comes to significant reduction in death, NEC, LOS and feeding intolerance at a cost of less than a dollar a day irrespective of the setting and baseline incidence of NEC. The common controversies that are preventing the rapid uptake of probiotics for preterm infants are addressed in this paper.

Impact of an In-House Pediatric Surgery Unit and Human Milk Centered Enteral Nutrition on Necrotizing Enterocolitis

The importance for mortality and morbidity of an in-house pediatric surgery unit for premature infants with necrotizing enterocolitis (NEC) remains undefined. Data on 389 consecutive very low birth weight infants with a birth weight <1250 g admitted between 2009 and 2014 was retrospectively analyzed in two almost identical neonatal intensive care units. Epidemiological data (n=172 and n=217, respectively) were comparable. Incidence of NEC stage II+ was significantly higher in center 1 (15.1 versus 5.5%, n=18 versus 6). This correlated with a significantly lower rate of exclusive human milk feeding compared to center 2 (24.2 versus 59.3%). Probiotic treatment did not differ. Importantly, in case of surgery the length of removed intestine (49.9 versus 19.5 cm) and the rate of severe short-bowel syndrome (38.9 versus 0 %) were significantly higher in center 1 (no in-house pediatric surgery). Furthermore, long-term morbidity assessment revealed more impaired motoric (-4.2 versus -2.2 months, p=0.21) and psychologic (-4.3 versus -1.6 months, p=0.09) development in center 1. Mortality was similar in both centers. Conclusions. Short- and possibly also long-term morbidity of NEC is clearly associated with the presence of an on-site pediatric surgery unit. Enteral nutrition with human milk seems to be a strong protective factor against NEC.

Low Diversity of Human Milk Oligosaccharides is Associated with Necrotising Enterocolitis in Extremely Low Birth Weight Infants

Difference in human milk oligosaccharides (HMO) composition in breast milk may be one explanation why some preterm infants develop necrotizing enterocolitis (NEC) despite being fed exclusively with breast milk. The aim of this study was to measure the concentration of 15 dominant HMOs in breast milk during the neonatal period and investigate how their levels correlated to NEC, sepsis, and growth in extremely low birth weight (ELBW; <1000 g) infants who were exclusively fed with breast milk. Milk was collected from 91 mothers to 106 infants at 14 and 28 days and at postmenstrual week 36. The HMOs were analysed with high-performance anion-exchange chromatography with pulsed amperometric detection. The HMOs diversity and the levels of Lacto-N-difucohexaose I were lower in samples from mothers to NEC cases, as compared to non-NEC cases at all sampling time points. Lacto-N-difucohexaose I is only produced by secretor and Lewis positive mothers. There were also significant but inconsistent associations between 3′-sialyllactose and 6′-sialyllactose and culture-proven sepsis and significant, but weak correlations between several HMOs and growth rate. Our results suggest that the variation in HMO composition in breast milk may be an important factor explaining why exclusively breast milk fed ELBW infants develop NEC.

Probiotics in Autoimmune and Inflammatory Disorders

Probiotics have been used to ameliorate gastrointestinal symptoms since ancient times. Over the past 40 years, probiotics have been shown to impact the immune system, both in vivo and in vitro. This interaction is linked to gut microbes, their polysaccharide antigens, and key metabolites produced by these bacteria. At least four metabolic pathways have been implicated in mechanistic studies of probiotics, based on mechanistic studies in animal models. Microbial⁻immune system crosstalk has been linked to: short-chain fatty acid production and signaling, tryptophan metabolism and the activation of aryl hydrocarbon receptors, nucleoside signaling in the gut, and activation of the intestinal histamine-2 receptor. Several randomized controlled trials have now shown that microbial modification by probiotics may improve gastrointestinal symptoms and multiorgan inflammation in rheumatoid arthritis, ulcerative colitis, and multiple sclerosis. Future work will need to carefully assess safety issues, selection of optimal strains and combinations, and attempts to prolong the duration of colonization of beneficial microbes.

Filling the Gaps: Current Research Directions for a Rational Use of Probiotics in Preterm Infants

The use of probiotics among very low-birth-weight infants is constantly increasing, as probiotics are believed to reduce the incidence of severe diseases such as necrotizing enterocolitis and late-onset sepsis and to improve feeding tolerance. However, despite the enthusiasm towards these products in neonatal medicine, theoretical knowledge and clinical applications still need to be improved. The purpose of this review is to give an overview of the most important gaps in the current literature about potential uses of probiotics in preterm infants, highlighting promising directions for future research. Specifically, further well-designed studies should aim at clarifying the impact of the type of feeding (mother's milk, donor milk, and formula) on the relationship between probiotic supplementation and clinical outcome. Moreover, future research is needed to provide solid evidence about the potential greater efficacy of multi-strain probiotics compared to single-strain products. Safety issues should also be addressed properly, by exploring the potential of paraprobiotics and risks connected to antibiotic resistance in preterm infants. Last, in light of increasing commercial and public interests, the long-term effect of routine consumption of probiotics in such a vulnerable population should be also evaluated.

Probiotics for Preterm Infants: A Strain-Specific Systematic Review and Network Meta-analysis

OBJECTIVES

Several randomized controlled trials (RCTs) on the use of probiotics to reduce morbidity and mortality in preterm infants have provided inconsistent results. Although meta-analyses that group all of the used strains together are suggesting efficacy, it is not possible to determine the most effective strain that is more relevant to the clinician. We therefore used a network meta-analysis (NMA) approach to identify strains with greatest efficacy.

METHODS

A PubMed search identified placebo-controlled or head-to-head RCTs investigating probiotics in preterm infants. From trials that recorded mortality, necrotizing enterocolitis, late-onset sepsis, or time until full enteral feeding as outcomes, data were extracted and Bayesian hierarchical random-effects models were run to construct a NMA.

RESULTS

Fifty-one RCTs involving 11,231 preterm infants were included. Most strains or combinations of strains were only studied in one or a few RCTs. Only 3 of 25 studied probiotic treatment combinations showed significant reduction in mortality rates. Seven treatments reduced necrotizing enterocolitis incidence, 2 reduced late-onset sepsis, and 3 reduced time until full enteral feeding. There was no clear overlap of strains, which were effective on multiple outcome domains.

CONCLUSIONS

This NMA showed efficacy in reducing mortality and morbidity only in a minority of the studied strains or combinations. This may be due to an inadequate number, or size, of RCTs, or due to a true lack of effect for certain species. Further large and adequately powered RCTs using strains with the greatest apparent efficacy will be needed to more precisely define optimal treatment strategies.

Probiotics and necrotizing enterocolitis

In this review, we summarize existing knowledge regarding the effects of probiotics on necrotizing enterocolitis (NEC). We review the role of the microbiome in NEC and pre-clinical data on mechanisms of probiotic action. Next, we summarize existing randomized controlled trials and observational studies of probiotics to prevent NEC. We also summarize findings from several recent meta-analyses and report a new cumulative meta-analysis of probiotic trials. Finally, we review data from cohorts routinely using commercially available probiotics. Our goal is to inform clinicians about the risks and benefits of probiotics, which may be helpful for those considering use in preterm infants to prevent NEC, death, or sepsis.

Probiotic supplementation in preterm infants does not affect the risk of retinopathy of prematurity: a meta-analysis of randomized controlled trials

Retinopathy of prematurity (ROP) is a vascular disorder of the developing retina in preterm infants and is a leading cause of childhood blindness. Perinatal infection plays a pathogenic role in ROP. Probiotic supplementation reduces the risk of late onset sepsis (LOS) in preterm infants but it remains to be determined whether this reduction translates into a reduction of other complications. We conducted a systematic review and meta-analysis to evaluate the possible role of probiotics in altering the risk of ROP. Eleven randomized controlled trials (4250 infants; probiotics: 2121) were included in the meta-analysis that showed a significantly decreased rate of LOS with a risk ratio (RR) of 0.807 and a 95% confidence interval (CI) of 0.705 to 0.924 (P = 0.010; fixed effects model) but could not demonstrate a significant effect of probiotics on any stage ROP (RR 1.053, 95% CI 0.903 to 1.228, P = 0.508, 4 studies), or severe ROP (RR 0.841, 95% CI 0.666 to 1.063, P = 0.148, 9 studies). Meta-regression did not show any significant association between the RR for LOS and the RR for severe ROP. In conclusion, our results suggest that infection prevention by probiotics does not affect the risk of developing ROP in preterm infants.