Histamine-2 receptor blockers alter the fecal microbiota in premature infants

Development of antibiotic resistome in premature infants

Preterm birth is a major concern in neonatal care, significantly impacting infant survival and long-term health. The gut microbiome, essential for infant development, often becomes imbalanced in preterm infants, making it crucial to understand the effects of antibiotics on its development. Our study analyzed weekly, 6-month, and 1-year stool samples from 100 preterm infants, correlating clinical data on antibiotic use and feeding patterns. Comparing infants who received no antibiotics with those given empirical post-birth treatment, we observed notable alterations in the gut microbiome's composition and an increase in antibiotic resistance gene abundance early in life. Although these effects diminished over time, their long-term clinical impacts remain unclear. Human milk feeding was associated with beneficial microbiota like Actinobacteriota and reduced antibiotic resistance genes, underscoring its protective role. This highlights the importance of judicious antibiotic use and promoting human milk to foster a healthy gut microbiome in preterm infants.

Sociodemographic Factors and Intestinal Microbiome Development in Preterm, Very Low Birth Weight Infants

OBJECTIVE

Preterm very low birth weight (VLBW) infants are at risk for intestinal morbidities and dysbiotic development of the intestinal microbiome. Despite the influence of sociodemographic factors on premature infant health outcomes, whether they shape the intestinal microbiome early in life is not clear. The objective was to explore the associations between race, sex, and socioeconomic status and the intestinal microbiome of VLBW infants during the first 4 weeks of life.

STUDY DESIGN

This was a secondary analysis of data from an ongoing randomized trial of 79 infants ≤30 weeks' gestation and ≤1,500 g. Stool samples were collected at week 1 through week 4, frozen to -80°C and analyzed by 16S rRNA sequencing of the V4 region using Illumina MiSeq. Reads were analyzed to measure α and β diversity as well as relative abundance of bacteria in the intestinal microbiome.

RESULTS

Of the 79 infants, 63 had at least one sample available. Twenty-three (37%) of infants were African American, 30 (48%) were male, and 44 (71%) had Medicaid insurance. There were no statistically significant (<0.05) differences in α diversity or β diversity, and the differential abundance analysis suggests limited patterns of distinction in the intestinal microbiome between non-African American and African American infants, male and female infants, and infants with maternal private or Medicaid insurance.

CONCLUSION

Our results suggest race, sex, and socioeconomic status shape colonization of specific microorganisms to a limited extent. Future studies should confirm these findings and determine clinical relevance through further study of differentially abundant microorganisms and additional factors contributing to colonization patterns.

KEY POINTS

· Diversity of the gut microbiome was similar between infants of varying race, sex, and socioeconomic status.. · We observed sociodemographic-linked differences in colonization of individual taxa.. · Further study is required to confirm these results and the clinical relevance of these findings..

Exposure to prescribed medication in early life and impacts on gut microbiota and disease development

The gut microbiota during early life plays a crucial role in infant development. This microbial-host interaction is also essential for metabolism, immunity, and overall human health in later life. Early-life pharmaceutical exposure, mainly referring to exposure during pregnancy, childbirth, and infancy, may change the structure and function of gut microbiota and affect later human health. In this Review, we describe how healthy gut microbiota is established in early life. We summarise the commonly prescribed medications during early life, including antibiotics, acid suppressant medications and other medications such as antidepressants, analgesics and steroid hormones, and discuss how these medication-induced changes in gut microbiota are involved in the pathological process of diseases, including infections, inflammatory bowel disease, metabolic diseases, allergic diseases and neurodevelopmental disorders. Finally, we review some critical methods such as dietary therapy, probiotics, prebiotics, faecal microbiota transplantation, genetically engineered phages, and vagus nerve stimulation in early life, aiming to provide a new strategy for the prevention of adverse health outcomes caused by prescribed medications exposure in early life.

Gastroesophageal reflux and PPI exposure alter gut microbiota in very young infants

Importance

Infants with symptomatic Gastroesophageal reflux are treated with pharmacological therapy that includes proton pump inhibitors (PPI) with clinical improvement. The alterations to gut microbiome profiles in comparison to infants without reflux is not known.

Objective

To determine the effect of PPI therapy on gut bacterial richness, diversity, and proportions of specific taxa in infants when compared to infants not exposed to acid suppressive therapy.

Design setting and participants

This cohort study was conducted at the Stony Brook Hospital in Stony Brook, NY between February 2016, and June 2019. Infants meeting inclusion criteria were enrolled in a consecutive fashion.

Results

A total of 76 Infants were recruited and 60 were enrolled in the study, Twenty nine infants met clinical criteria for reflux and were treated with PPI therapy: median [IQR] gestation: 38.0 weeks [34.7-39.6 weeks]; median [IQR] birthweight: 2.95 Kg [2.2-3.4]; 14 [46.7%] male) and 29 infant were healthy controls median [IQR] gestation: 39.1 weeks [38-40 weeks]; median [IQR] birthweight: 3.3 Kg [2.2-3.4]; 17 [58.6%] male); 58 stool samples from 58 infants were analyzed. There were differences in Shannon diversity between the reflux and control groups. The reflux group that was exposed to PPI therapy had increased relative abundance of a diverse set of genera belonging to the phylum Firmicutes. On the other hand, the control group microbiota was dominated by Bifidobacterium, and a comparatively lower level of enrichment and abundance of microbial taxa was observed in this group of infants.

Conclusions and relevance

We observed significant differences in both α- and β-diversity of the microbiome, when the two groups of infants were compared. The microbiome in the reflux group had more bacterial taxa and the duration of PPIs exposure was clearly associated with the diversity and abundance of gut microbes. These findings suggest that PPI exposure among infants results in early enrichment of the intestinal microbiome.

Araújo J, Marques C, Sousa L, Morais J, Castela I, Faria A, Neto MT, Cordeiro-Ferreira G, Virella D, Pita A, Pereira-da-Silva L, Calhau C. Changes in Microbiota Profile in the Proximal Remnant Intestine in Infants Undergoing Surgery Requiring Enterostomy

Early-life gut dysbiosis has been associated with an increased risk of inflammatory, metabolic, and immune diseases later in life. Data on gut microbiota changes in infants undergoing intestinal surgery requiring enterostomy are scarce. This prospective cohort study examined the enterostomy effluent of 29 infants who underwent intestinal surgery due to congenital malformations of the gastrointestinal tract, necrotizing enterocolitis, or spontaneous intestinal perforation. Initial effluent samples were collected immediately after surgery and final effluent samples were collected three weeks later. Gut microbiota composition was analysed using real-time PCR and 16S rRNA gene sequencing. Three weeks after surgery, an increase in total bacteria number (+21%, p = 0.026), a decrease in Staphylococcus (-21%, p = 0.002) and Candida spp. (-16%, p = 0.045), and an increase in Lactobacillus (+3%, p = 0.045) and in less abundant genera belonging to the Enterobacteriales family were found. An increase in alpha diversity (Shannon's and Simpson's indexes) and significant alterations in beta diversity were observed. A correlation of necrotizing enterocolitis with higher Staphylococcus abundance and higher alpha diversity was also observed. H2-blockers and/or proton pump inhibitor therapy were positively correlated with a higher total bacteria number. In conclusion, these results suggest that positive changes occur in the gut microbiota profile of infants three weeks after intestinal surgery.

Differential impact of proton pump inhibitor on survival outcomes of patients with advanced urothelial carcinoma treated with chemotherapy versus pembrolizumab

OBJECTIVES

We clarified the effect of concomitant proton pump inhibitor use on oncological outcomes in patients with advanced urothelial carcinoma treated either with chemotherapy or immune checkpoint inhibitor.

METHODS

We retrospectively reviewed patients with advanced urothelial carcinoma who received paclitaxel-gemcitabine therapy or pembrolizumab after platinum-based chemotherapy. The patients were divided into four groups based on the treatment regimen and the concomitant use of proton pump inhibitor. We compared survival outcomes between the groups and determined which factors predicted overall survival.

RESULTS

Among the 60 and 75 patients treated with paclitaxel-gemcitabine and pembrolizumab, 15 and 29 used a concomitant proton pump inhibitor. Progression-free and overall survival was significantly shorter in patients who were administered pembrolizumab with concomitant proton pump inhibitor compared to those without. The use of a concomitant proton pump inhibitor had no effect on survival outcomes in patients who received paclitaxel-gemcitabine therapy. Furthermore, progression-free and overall survival were significantly shorter in patients treated with paclitaxel-gemcitabine therapy compared to those treated with pembrolizumab among patients without concomitant proton pump inhibitor. In contrast, there was no difference in survival outcomes between the two regimens among patients with concomitant proton pump inhibitor. Concomitant proton pump inhibitor use was associated with poor overall survival only in patients treated with pembrolizumab.

CONCLUSION

The use of a concomitant proton pump inhibitor use had no impact on oncological outcomes in patients with advanced urothelial carcinoma treated with paclitaxel-gemcitabine therapy, different from those treated with pembrolizumab.

State-of-the-art review and update of in vivo models of necrotizing enterocolitis

NEC remains one of the most common causes of mortality and morbidity in preterm infants. Animal models of necrotizing enterocolitis (NEC) have been crucial in improving our understanding of this devastating disease and identifying biochemical pathways with therapeutic potential. The pathogenesis of NEC remains incompletely understood, with no specific entity that unifies all infants that develop NEC. Therefore, investigators rely on animal models to manipulate variables and provide a means to test interventions, making them valuable tools to enhance our understanding and prevent and treat NEC. The advancements in molecular analytic tools, genetic manipulation, and imaging modalities and the emergence of scientific collaborations have given rise to unique perspectives and disease correlates, creating novel pathways of investigation. A critical review and understanding of the current phenotypic considerations of the highly relevant animal models of NEC are crucial to developing novel therapeutic and preventative strategies for NEC.

The Nonbacterial Microbiome: Fungal and Viral Contributions to the Preterm Infant Gut in Health and Disease

The intestinal microbiome is frequently implicated in necrotizing enterocolitis (NEC) pathogenesis. While no particular organism has been associated with NEC development, a general reduction in bacterial diversity and increase in pathobiont abundance has been noted preceding disease onset. However, nearly all evaluations of the preterm infant microbiome focus exclusively on the bacterial constituents, completely ignoring any fungi, protozoa, archaea, and viruses present. The abundance, diversity, and function of these nonbacterial microbes within the preterm intestinal ecosystem are largely unknown. Here, we review findings on the role of fungi and viruses, including bacteriophages, in preterm intestinal development and neonatal intestinal inflammation, with potential roles in NEC pathogenesis yet to be determined. In addition, we highlight the importance of host and environmental influences, interkingdom interactions, and the role of human milk in shaping fungal and viral abundance, diversity, and function within the preterm intestinal ecosystem.

Models of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of death and disability from gastrointestinal disease in premature infants. The mortality of patients with NEC is approximately 30%, a figure that has not changed in many decades, reflecting the need for a greater understanding of its pathogenesis. Progress towards understanding the cellular and molecular mechanisms underlying NEC requires the study of highly translational animal models. Such animal models must mimic the biology and physiology of premature infants, while still allowing for safe experimental manipulation of environmental and microbial factors thought to be associated with the risk and severity of NEC. Findings from animal models have yielded insights into the interactions between the host, the colonizing microbes, and the innate immune receptor Toll-like Receptor 4 (TLR4) in driving disease development. This review discusses the relative strengths and weaknesses of available in vivo, in vitro, and NEC-in-a-dish models of this disease. We also highlight the unique contributions that each model has made to our understanding of the complex interactions between enterocytes, microbiota, and immune cells in the pathogenesis of NEC. The overall purpose of this review is to provide a menu of options regarding currently available animal models of NEC, while in parallel hopefully reducing the potential uncertainty and confusion regarding NEC models to assist those who wish to enter this field from other disciplines.

Prevention of Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is considered to be one of the most devastating intestinal diseases seen in neonatal intensive care. Measures to treat NEC are often too late, and we need effective preventative measures to alleviate the burden of this disease. The purpose of this review is to summarize currently used measures, and those showing future promise for prevention.

A systematic review of the factors influencing microbial colonization of the preterm infant gut

Prematurity coupled with the necessary clinical management of preterm (PT) infants introduces multiple factors that can interfere with microbial colonization. This study aimed to review the perinatal, physiological, pharmacological, dietary, and environmental factors associated with gut microbiota of PT infants. A total of 587 articles were retrieved from a search of multiple databases. Sixty studies were included in the review after removing duplicates and articles that did not meet the inclusion criteria. Review of this literature revealed that evidence converged on the effect of postnatal age, mode of delivery, use of antibiotics, and consumption of human milk in the composition of gut microbiota of PT infants. Less evidence was found for associations with race, sex, use of different fortifiers, macronutrients, and other medications. Future studies with rich metadata are needed to further explore the impact of the PT exposome on the development of the microbiota in this high-risk population.

The Relationship Between Maternal and Neonatal Microbiota in Spontaneous Preterm Birth: A Pilot Study

The newborn's microbiota composition at birth seems to be influenced by maternal microbiota. Maternal vaginal microbiota can be a determining factor of spontaneous Preterm Birth (SP^PTB), the leading cause of perinatal mortality. The aim of the study is to investigate the likelihood of a causal relationship between the maternal vaginal microbiota composition and neonatal lung and intestinal microbiota profile at birth, in cases of SP^PTB. The association between the lung and/or meconium microbiota with the subsequent development of bronchopulmonary dysplasia (BPD) was also investigated. Maternal vaginal swabs, newborns' bronchoalveolar lavage fluid (BALF) (1st, 3rd, 7th day of life) and first meconium samples were collected from 20 women and 23 preterm newborns with gestational age ≤ 30 weeks (12 = SP^PTB; 11 = Medically Indicated Preterm Birth-MI^PTB). All the samples were analyzed for culture examination and for microbiota profiling using metagenomic analysis based on the Next Generation Sequencing (NGS) technique of the bacterial 16S rRNA gene amplicons. No significant differences in alpha e beta diversity were found between the neonatal BALF samples of SP^PTB group and the MI^PTB group. The vaginal microbiota of mothers with SP^PTB showed a significant difference in alpha diversity with a decrease in Lactobacillus and an increase in Proteobacteria abundance. No association was found between BALF and meconium microbiota with the development of BPD. Vaginal colonization by Ureaplasma bacteria was associated with increased risk of both SP^PTB and newborns' BPD occurrence. In conclusion, an increase in α-diversity values and a consequent fall in Lactobacillus in vaginal environment could be associated to a higher risk of SP^PTB. We could identify neither a specific neonatal lung or meconium microbiota profiles in preterm infants born by SP^PTB nor a microbiota at birth suggestive of subsequent BPD development. Although a strict match has not been revealed between microbiota of SP^PTB mother-infant couples, a relationship cannot be excluded. To figure out the reciprocal influence of the maternal-neonatal microbiota and its potential role in the pathogenesis of SP^PTB and BPD further research is needed.

Malnutrition, poor post-natal growth, intestinal dysbiosis and the developing lung

In extremely preterm infants, poor post-natal growth, intestinal dysbiosis and bronchopulmonary dysplasia are common, and each is associated with long-term complications. The central hypothesis that this review will address is that these three common conditions are interrelated. Challenges to studying this hypothesis include the understanding that malnutrition and poor post-natal growth are not synonymous and that there is not agreement on what constitutes a normal intestinal microbiota in this evolutionarily new population. If this hypothesis is supported, further study of whether "correcting" intestinal dysbiosis in extremely preterm infants reduces postnatal growth restriction and/or bronchopulmonary dysplasia is indicated.

Gastro-oesophageal reflux disease

Gastro-oesophageal reflux disease (GERD) is a common disorder in adults and children. The global prevalence of GERD is high and increasing. Non-erosive reflux disease is the most common phenotype of GERD. Heartburn and regurgitation are considered classic symptoms but GERD may present with various atypical and extra-oesophageal manifestations. The pathophysiology of GERD is multifactorial and different mechanisms may result in GERD symptoms, including gastric composition and motility, anti-reflux barrier, refluxate characteristics, clearance mechanisms, mucosal integrity and symptom perception. In clinical practice, the diagnosis of GERD is commonly established on the basis of response to anti-reflux treatment; however, a more accurate diagnosis requires testing that includes upper gastrointestinal tract endoscopy and reflux monitoring. New techniques and new reflux testing parameters help to better phenotype the condition. In children, the diagnosis of GERD is primarily based on history and physical examination and treatment vary with age. Treatment in adults includes a combination of lifestyle modifications with pharmacological, endoscopic or surgical intervention. In refractory GERD, optimization of proton-pump inhibitor treatment should be attempted before a series of diagnostic tests to assess the patient's phenotype.

Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is an inflammatory disease affecting premature infants. Intestinal microbial composition may play a key role in determining which infants are predisposed to NEC and when infants are at highest risk of developing NEC. It is unclear how to optimize antibiotic therapy in preterm infants to prevent NEC and how to optimize antibiotic regimens to treat neonates with NEC. This article discusses risk factors for NEC, how dysbiosis in preterm infants plays a role in the pathogenesis of NEC, and how probiotic and antibiotic therapy may be used to prevent and/or treat NEC and its sequelae.

Antacid exposure and immunotherapy outcomes among patients with advanced hepatocellular carcinoma

BACKGROUND

Antibiotic exposure has been associated with worse outcomes with immune checkpoint inhibitors (ICIs) in cancer patients, likely due to disruption of the gut microbiome. Other commonly prescribed medications, such as proton pump inhibitors (PPIs) and histamine-2-receptor antagonists (H2RAs), are also known to disrupt the microbiome, but data on their association with ICI outcomes are conflicting.

METHODS

We conducted a retrospective, multicenter, international cohort study including 314 hepatocellular carcinoma (HCC) patients treated with ICIs from 2017 to 2019 to assess the association between PPI or H2RA exposure (up to 30 days before ICI) and overall survival. Secondary outcomes included overall response rate (ORR) and development of any treatment-related adverse events (AEs).

RESULTS

Baseline PPI/H2RA exposure was not associated with overall survival in univariable (HR 1.01, 95% CI 0.75-1.35) or multivariable analysis (HR 0.98, 95% CI 0.71-1.36). Baseline PPI/H2RA exposure was not associated with either ORR (OR 1.32, 95% CI 0.66-2.65) or AEs (OR 1.07, 95% CI 0.54-2.12) in multivariable analysis.

CONCLUSIONS

Our results suggest that exposure to PPI/H2RA prior to ICIs does not adversely affect outcomes in HCC patients.

Methods for exploring the faecal microbiome of premature infants: a review

The premature infant gut microbiome plays an important part in infant health and development, and recognition of the implications of microbial dysbiosis in premature infants has prompted significant research into these issues. The approaches to designing investigations into microbial populations are many and varied, each with its own benefits and limitations. The technique used can influence results, contributing to heterogeneity across studies. This review aimed to describe the most common techniques used in researching the preterm infant microbiome, detailing their various limitations. The objective was to provide those entering the field with a broad understanding of available methodologies, so that the likely effects of their use can be factored into literature interpretation and future study design. We found that although many techniques are used for characterising the premature infant microbiome, 16S rRNA short amplicon sequencing is the most common. 16S rRNA short amplicon sequencing has several benefits, including high accuracy, discoverability and high throughput capacity. However, this technique has limitations. Each stage of the protocol offers opportunities for the injection of bias. Bias can contribute to variability between studies using 16S rRNA high throughout sequencing. Thus, we recommend that the interpretation of previous results and future study design be given careful consideration.

The Effects of Genetic Relatedness on the Preterm Infant Gut Microbiota

The preterm infant gut microbiota is influenced by environmental, endogenous, maternal, and genetic factors. Although siblings share similar gut microbial composition, it is not known how genetic relatedness affects alpha diversity and specific taxa abundances in preterm infants. We analyzed the 16S rRNA gene content of stool samples, ≤ and >3 weeks postnatal age, and clinical data from preterm multiplets and singletons at two Neonatal Intensive Care Units (NICUs), Tampa General Hospital (TGH; FL, USA) and Carle Hospital (IL, USA). Weeks on bovine milk-based fortifier (BMF) and weight gain velocity were significant predictors of alpha diversity. Alpha diversity between siblings were significantly correlated, particularly at ≤3 weeks postnatal age and in the TGH NICU, after controlling for clinical factors. Siblings shared higher gut microbial composition similarity compared to unrelated individuals. After residualizing against clinical covariates, 30 common operational taxonomic units were correlated between siblings across time points. These belonged to the bacterial classes Actinobacteria, Bacilli, Bacteroidia, Clostridia, Erysipelotrichia, and Negativicutes. Besides the influence of BMF and weight variables on the gut microbial diversity, our study identified gut microbial similarities between siblings that suggest genetic or shared maternal and environmental effects on the preterm infant gut microbiota.

The impact of aspirin on Klebsiella pneumoniae liver abscess in diabetic patients

In this study, we aimed to investigate the impact of aspirin on the risk of pyogenic liver abscess caused by Klebsiella pneumoniae (KP-PLA) and invasive KP-PLA syndrome (IKPS) in diabetic patients. Diabetic patients who were propensity-score matched were retrospectively included from hospital-based database. Kaplan-Meier approach with a log-rank test was used to compare the cumulative incidences of KP-PLA including IKPS between aspirin users and non-users. Totally, 63,500 patients were analyzed after propensity-score matching (1:1). Compared with that of non-users, the incidence of KP-PLA was significantly reduced in aspirin users (0.31% vs. 0.50%, p < 0.01), but not for that of IKPS (0.02% vs. 0.03%, p = 0.29). Patients taking aspirin for ≥ 90 days had a significantly lower risk for KP-PLA (hazard ratio, 0.67; 95%CI, 0.50-0.90). Females, taking clopidogrel or metformin for ≥ 90 days, and taking H2-blockers or proton pump inhibitors (PPIs) for ≥ 5 days were also associated with a lower risk of KP-PLA. However, cholangitis and a glycated hemoglobin ≥ 8.5% were associated with an increased risk of KP-PLA.

Histamine H2-Receptor Antagonists Improve Non-Steroidal Anti-Inflammatory Drug-Induced Intestinal Dysbiosis

Dysbiosis, an imbalance of intestinal flora, can cause serious conditions such as obesity, cancer, and psychoneurological disorders. One cause of dysbiosis is inflammation. Ulcerative enteritis is a side effect of non-steroidal anti-inflammatory drugs (NSAIDs). To counteract this side effect, we proposed the concurrent use of histamine H₂ receptor antagonists (H₂RA), and we examined the effect on the intestinal flora. We generated a murine model of NSAID-induced intestinal mucosal injury, and we administered oral H₂RA to the mice. We collected stool samples, compared the composition of intestinal flora using terminal restriction fragment length polymorphism, and performed organic acid analysis using high-performance liquid chromatography. The intestinal flora analysis revealed that NSAID [indomethacin (IDM)] administration increased Erysipelotrichaceae and decreased Clostridiales but that both had improved with the concurrent administration of H₂RA. Fecal levels of acetic, propionic, and n-butyric acids increased with IDM administration and decreased with the concurrent administration of H₂RA. Although in NSAID-induced gastroenteritis the proportion of intestinal microorganisms changes, leading to the deterioration of the intestinal environment, concurrent administration of H₂RA can normalize the intestinal flora.

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.

Safety and efficacy of probiotic administration to preterm infants: ten common questions

In spite of a large number of randomized placebo-controlled clinical trials and observational cohort studies including >50,000 preterm infants from 29 countries that have demonstrated a decrease in the risk of necrotizing enterocolitis, death, and sepsis, routine prophylactic probiotic administration to preterm infants remains uncommon in much of the world. This manuscript reflects talks given at NEC Society Symposium in 2019 and is not intended to be a state-of-the-art review or systematic review, but a summary of the probiotic-specific aspects of the symposium with limited additions including a recent strain-specific network analysis and position statement from the European Society for Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN). We address ten common questions related to the intestinal microbiome and probiotic administration to the preterm infant.

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.

The infant microbiome and implications for central nervous system development

Neurodevelopmental impairment remains a significant morbidity in former very low birth weight premature infants. There is increasing evidence the microbiome affects neurodevelopment but mechanistic causes are largely unknown. There are many factors which affect the developing microbiome in infants including mode of delivery, feeding, medications, and environmental exposures. The overall impact of these factors may differ between premature and term infants. The microbiome and brain have well recognized bidirectional communication pathways via neural, hormonal, and immunologic mechanisms. Understanding the interplay between these different pathways has been possible with the use of animal models, particularly germ-free mice. The intricate relationship between the microbiome and the brain remains a research priority not only to improve the care, but to also improve the long-term neurodevelopmental outcomes in this vulnerable population.

[Prevention, diagnosis and treatment of necrotising enterocolitis in newborns less than 32 weeks at birth in Spain]

OBJECTIVES

To describe preventive, diagnostic and therapeutic strategies regarding necrotising enterocolitis in Spain and to identify the strengths, areas of further improvement, and future research lines.

METHODS

Two questionnaires on the management of preterm infants less than 32 weeks, at risk of, or with diagnosed necrotising enterocolitis, were distributed among selected representatives of the surgeons and neonatologists of the Spanish Neonatal Network (SEN1500) participant hospitals with a Paediatric Surgery Department.

RESULTS

Percentage of response was 77.1% of contacted surgeons and 88.6% of neonatologists. There is a written protocol on the diagnosis and medical management of necrotising enterocolitis in 52% of the hospitals, and as regards surgical treatment in 33%. There is wide access to donor bank milk and to staff dedicated to breastfeeding promotion (87%). On the contrary, only 52% of the centres perform delayed cord clamping, and probiotics are used in just 23%. The use of abdominal ultrasound is increasing. There are no large differences as regards duration of antibiotic use and bowel rest, whereas there was as regards antibiotic selection, surgical indication, and type of intervention.

CONCLUSIONS

As regards prevention, delayed cord clamping and extended access to donor milk are two possible aspects of further improvement. The observed discrepancies noted in diagnostic and therapeutic aspects are common in precisely the areas where evidence in the literature is weakest.

The Role of Glycosaminoglycans in Protection from Neonatal Necrotizing Enterocolitis: A Narrative Review

Necrotizing enterocolitis, a potentially fatal intestinal inflammatory disorder affecting primarily premature infants, is a significant cause of morbidity and mortality in neonates. While the etiology of the disease is, as yet, unknown, a number of risk factors for the development of necrotizing enterocolitis have been identified. One such risk factor, formula feeding, has been shown to contribute to both increased incidence and severity of the disease. The protective influences afforded by breastfeeding are likely attributable to the unique composition of human milk, an extremely potent, biologically active fluid. This review brings together knowledge on the pathogenesis of necrotizing enterocolitis and current thinking on the instrumental role of one of the more prominent classes of bioactive components in human breast milk, glycosaminoglycans.

Fecal dysbiosis in infants with cystic fibrosis is associated with early linear growth failure

Most infants with cystic fibrosis (CF) have pancreatic exocrine insufficiency that results in nutrient malabsorption and requires oral pancreatic enzyme replacement. Newborn screening for CF has enabled earlier diagnosis, nutritional intervention, and enzyme replacement for these infants, allowing most infants with CF to achieve their weight goals by 12 months of age¹. Nevertheless, most infants with CF continue to have poor linear growth during their first year of life¹. Although this early linear growth failure is associated with worse long-term respiratory function and survival^2,3, the determinants of stature in infants with CF have not been defined. Several characteristics of the CF gastrointestinal (GI) tract, including inflammation, maldigestion and malabsorption, could promote intestinal dysbiosis^4,5. As GI microbiome activities are known to affect endocrine functions^6,7, the intestinal microbiome of infants with CF might also impact growth. We identified an early, progressive fecal dysbiosis that distinguished infants with CF and low length from infants with CF and normal length. This dysbiosis included altered abundances of taxa that perform functions important for GI health, nutrient harvest, and growth hormone signaling, including decreased Bacteroidetes and increased Proteobacteria. Thus, the GI microbiota represent a potential therapeutic target to correct linear growth defects among infants with CF.

Neonatal intestinal dysbiosis

The initial colonization of the neonatal intestinal tract is influenced by delivery mode, feeding, the maternal microbiota, and a host of environmental factors. After birth, the composition of the infant's microbiota undergoes a series of significant changes particularly in the first weeks and months of life ultimately developing into a more stable and diverse adult-like population in childhood. Intestinal dysbiosis is an alteration in the intestinal microbiota associated with disease and appears to be common in neonates. The consequences of intestinal dysbiosis are uncertain, but strong circumstantial evidence and limited confirmations of causality suggest that dysbiosis early in life can influence the health of the infant acutely, as well as contribute to disease susceptibility later in life.

Determinants of the Very Low-Birth-Weight Infant's Intestinal Microbiome: A Systematic Review

The intestinal microbiome is the genetic material from microorganisms residing in the intestinal tract. Very low-birth-weight infants (VLBW; birth weight ≤1500 g) are a physiologically compromised population undergoing a unique period of initial intestinal microbiome establishment. Evidence supports a connection between the intestinal microbiome and gastrointestinal illness that disproportionately affects VLBW infants. Necrotizing enterocolitis, an inflammatory and often necrotic condition of the intestine, and late-onset sepsis, a bloodstream infection occurring after 3 days of life, are thought to be associated with delayed or abnormal intestinal microbiome development. Here, we review the determinants, or factors, that influence the VLBW infant's intestinal microbiome and discuss clinical implications. PubMed, Web of Science, EMBASE, and CINAHL were systematically searched for publications addressing factors with the potential to affect the intestinal microbiome of VLBW infants. Results indicate that infant's age and weight, mode of delivery, antibiotic exposure, medication use, feeding regime, environment, and perinatal-/infant-associated factors may be important determinants of the microbiome in this vulnerable population. Clinicians have opportunities to support positive development of the VLBW infant's intestinal microbiome through antibiotic stewardship, support of human milk feeding, and hygienic care practices.

Intestinal dysbiosis and necrotizing enterocolitis: assessment for causality using Bradford Hill criteria

In recent years, several studies have shown that premature infants who develop NEC frequently display enteric dysbiosis with increased Gram-negative bacteria for several days to weeks prior to NEC onset. The importance of these findings, for the possibility of a causal role of these bacteria in NEC pathogenesis, and for potential value of gut dysbiosis as a biomarker of NEC, is well-recognized. In this review, we present current evidence supporting the association between NEC in premature infants and enteric dysbiosis, and its evaluation using the Bradford Hill criteria for causality. To provide an objective appraisal, we developed a novel scoring system for causal inference. Despite important methodological and statistical limitations, there is support for the association from several large studies and a meta-analysis. The association draws strength from strong biological plausibility of a role of Gram-negative bacteria in NEC and from evidence for temporality, that dysbiosis may antedate NEC onset. The weakness of the association is in the low level of consistency across studies, and the lack of specificity of effect. There is a need for an improved definition of dysbiosis, either based on a critical threshold of relative abundances or at higher levels of taxonomic resolution.

Proinflammatory profile of neonatal monocytes induced by microbial ligands is downmodulated by histamine

Although the neonatal period is characterized by relative immunological immaturity, an inflammatory response due to Toll-like receptor (TLR) activation is observed. Histamine may be one of the factors playing a role in restraining inflammation during the early stages of life. Therefore, we evaluated the responsiveness of human cord blood cells to TLR4 agonists and the immunomodulatory function of histamine in the inflammatory response. Compared with adults, mononuclear cells (MNCs) from newborns (NBs) exhibit impaired production of IFN-γ-inducible chemokines, such as CXCL10 and CXCL9, upon lipopolysaccharide (LPS) stimulation. Notably, LPS induced a 5-fold increase in CCL2 secretion in NBs. Evaluation of the effect of histamine on LPS-induced CCL2 secretion showed an inhibitory effect in the majority of adults, whereas this effect was detectable in all NBs. Histamine receptor (HR) blockage revealed partial involvement of H1R, H2R and H4R in LPS-induced CCL2 inhibition in MNCs from both NBs and adults. As monocytes are the main type of mononuclear cell that produces CCL2, we evaluated genes related to TLR signaling upon LPS stimulation. Monocytes from NBs showed up-regulation of genes associated with JAK/STAT/NF-κB and IFN signaling. Some differentially expressed genes encoding proinflammatory factors were preferentially detected in LPS-activated monocytes from NBs, and markedly down-regulated by histamine. The immunomodulatory role of histamine on CCL2 and CXCL8 was detected at the transcript and protein levels. Our findings show that NBs have enhanced CCL2 responsiveness to LPS, and that histamine acts in immune homeostasis during the neonatal period to counterbalance the robustness of TLR stimulation.

Longitudinal changes in the gut microbiome of infants on total parenteral nutrition

BACKGROUND

Animal studies suggest that total parenteral nutrition (TPN) may alter bacterial colonization of the intestinal tract and contribute to complications. Progressive changes in gut microbiome of infants receiving TPN are not well understood.

METHODS

Infants with and without TPN/soy lipid were enrolled in a prospective, longitudinal study. Weekly fecal samples were obtained for the first 4 weeks of life. High throughput pyrosequencing of 16S rDNA was used for compositional analysis of the gut microbiome.

RESULTS

47 infants were eligible for analyses, 25 infants received TPN, and 22 infants did not (control). Although similar between TPN and control groups in the first week, fecal bacterial alpha diversity was significantly lower in the TPN group compared to controls at week 4 (Shannon index 1.0 vs 1.5, P-value = 0.03). The TPN group had significantly lower Bacteroidetes and higher Verrucomicrobia abundance compared to controls (P-values < 0.05), and these differences became more pronounced over time. At the genus level, TPN was associated with lower abundance of Bacteroides and Bifidobacterium in all weeks.

CONCLUSIONS

TPN is associated with significant loss of biodiversity and alterations in the pattern of gut microbial colonization of infants over time. TPN-associated dysbiosis may predispose infants to adverse NICU outcomes.

Prevention of allergy with diverse and healthy microbiota: an update

PURPOSE OF REVIEW

Microbiota consist of symbiotic microscopic neighbors that interact on and within our bodies in diverse and incompletely understood ways throughout our lifetime. Though various associations with allergic disease have been described, clear effective therapeutic interventions to prevent allergy have been elusive.

RECENT FINDINGS

The human microbiome is influenced by multiple factors, including: mode of infant delivery (vaginal vs. cesarean section), breastfeeding, diet, presence of siblings and pets, exposure to antibiotics and other medications (particularly antacids), lifestyle, and developmental context. Microbial species promoting atopic responses and tolerance have been described. Specific microbiota likely act through distinct metabolic pathways to promote the health of their human hosts, optimally directing the developing immune system away from pro-allergic, Th2-dominated responses to more T-regulatory-influenced behaviors.

SUMMARY

Evidence suggests that specific healthy infant microbiome signatures may influence development of some components of the allergic march of childhood by decreasing atopic dermatitis, asthma, and food allergy. Further understanding of factors that influence healthy microbiota may lead to specific strategies tailored for early intervention and disease prevention.

Association between histamine-2 receptor antagonists and adverse outcomes in neonates: A systematic review and meta-analysis

Background

The use of histamine-2 receptor antagonists (H₂RA) in neonates is still debated because of possible risk of infection, necrotizing enterocolitis (NEC) and increased mortality.

Aim

To review whether the use of H₂RA in neonates admitted to neonatal intensive care units (NICU) is associated with infection, NEC or mortality.

Materials and method

We performed a systematic search in PubMed, Web of Science and SCOPUS databases using the terms “histamine-2 receptor antagonists”, “infection”, “necrotizing enterocolitis”, “mortality”, “neonates” and related terms to identify studies published up to April 30, 2017. We included studies conducted in hospitalized neonates and exposed to H₂RA. The primary outcomes were infection, NEC and mortality. We included reports of infections with clinical signs and positive culture, and NEC according to Bell stages (stage ≥II) based on standardised clinical and radiologic criteria. Among 1,144 studies identified, 10 fulfilled the selection criteria. Information extracted included study design, sample size and number of participants, along with the outcomes of interest. We conducted a meta-analysis of adjusted data and pooled estimates of infection, NEC and mortality are reported as odds ratios (OR) and 95% confidence intervals (95%CI).

Results

Ten studies were analysed. There were substantial associations between H₂RA and infection (pooled OR: 2.09; 95%CI: 1.35–3.24; P = 0.001) and NEC (pooled OR: 2.81, 95%CI: 1.19–6.64; P = 0.02) but not with the mortality risk (pooled OR: 1.76; 95%CI: 0.50–6.16; P: 0.38).

Conclusion

Current evidence suggests that H₂RA is associated with an increased risk of infection and NEC, but not with mortality in neonates admitted to NICU. The use of H₂RA in neonates must be stringently considered when necessary.

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.

Necrotizing Enterocolitis Pathophysiology: How Microbiome Data Alter Our Understanding

Necrotizing enterocolitis is a major cause of mortality and morbidity in the preterm infant population. The gut microbiome is of particular interest in research surrounding necrotizing enterocolitis, because variations in the intestinal microbiota seem to correlate with the risk of inflammation and disease. Recent advances in non-culture-based genomic sequencing have also allowed for more intricate analyses of the intestinal microbiome. Its evolution seems to be influenced by intrauterine and extrauterine factors, ranging from antenatal antibiotic exposure to type of enteral feeds. Ultimately, these alterations in the gut microbiome have the potential to result in devastating diseases like necrotizing enterocolitis.

Antibiotic and acid-suppression medications during early childhood are associated with obesity

OBJECTIVE

Gut microbiota alterations are associated with obesity. Early exposure to medications, including acid suppressants and antibiotics, can alter gut biota and may increase the likelihood of developing obesity. We investigated the association of antibiotic, histamine-2 receptor antagonist (H2RA) and proton pump inhibitor (PPI) prescriptions during early childhood with a diagnosis of obesity.

DESIGN

We performed a cohort study of US Department of Defense TRICARE beneficiaries born from October 2006 to September 2013. Exposures were defined as having any dispensed prescription for antibiotic, H2RA or PPI medications in the first 2 years of life. A single event analysis of obesity was performed using Cox proportional hazards regression.

RESULTS

333 353 children met inclusion criteria, with 241 502 (72.4%) children prescribed an antibiotic, 39 488 (11.8%) an H2RA and 11 089 (3.3%) a PPI. Antibiotic prescriptions were associated with obesity (HR 1.26; 95% CI 1.23 to 1.28). This association persisted regardless of antibiotic class and strengthened with each additional class of antibiotic prescribed. H2RA and PPI prescriptions were also associated with obesity, with a stronger association for each 30-day supply prescribed. The HR increased commensurately with exposure to each additional medication group prescribed.

CONCLUSIONS

Antibiotics, acid suppressants and the combination of multiple medications in the first 2 years of life are associated with a diagnosis of childhood obesity. Microbiota-altering medications administered in early childhood may influence weight gain.

Necrotizing enterocolitis: The intestinal microbiome, metabolome and inflammatory mediators

Necrotizing enterocolitis (NEC) is a disease of preterm infants and associated with significant mortality and morbidity. Although the pathogenesis of NEC is not clear, microbial dysbiosis, with a bloom of the phylum Proteobacteria, has been reported. Antibiotics and the use of H₂ blockers, which affect the gut microbiome, are associated with increased incidence of NEC. In association with dysbiosis, inflammatory processes are upregulated with increased Toll-like receptor signaling, leading to translocation of nuclear factor kappa-β, a transcription factor that induces transcription of various pro-inflammatory cytokines and chemokines. Microbial metabolites, short chain fatty acids including acetate and butyrate, may modulate immunity, inflammation, intestinal integrity and regulate transcription by epigenetic mechanisms. Evaluation of microbiome and metabolome may provide biomarkers for early diagnosis of NEC and microbial therapeutic approaches to correct microbial dysbiosis.

Gastrointestinal Development: Implications for Management of Preterm and Term Infants

The gastrointestinal (GI) system provides digestive, absorptive, neuroendocrine, and immunologic functions to support overall health. If normal development is interrupted, a variety of complications and disease can arise. This article explores normal development of the GI tract and specific clinical challenges pertinent to preterm and term infants. Specific topics include abnormal motility, gastroesophageal reflux, current feeding recommendations for preterm infants, effects of parenteral nutrition, and the relationship between the GI tract and the immune system.

Child Weight Gain Trajectories Linked To Oral Microbiota Composition

Gut and oral microbiota perturbations have been observed in obese adults and adolescents; less is known about their influence on weight gain in young children. Here we analyzed the gut and oral microbiota of 226 two-year-olds with 16S rRNA gene sequencing. Weight and length were measured at seven time points and used to identify children with rapid infant weight gain (a strong risk factor for childhood obesity), and to derive growth curves with innovative Functional Data Analysis (FDA) techniques. We showed that growth curves were associated negatively with diversity, and positively with the Firmicutes-to-Bacteroidetes ratio, of the oral microbiota. We also demonstrated an association between the gut microbiota and child growth, even after controlling for the effect of diet on the microbiota. Lastly, we identified several bacterial genera that were associated with child growth patterns. These results suggest that by the age of two, the oral microbiota of children with rapid infant weight gain may have already begun to establish patterns often seen in obese adults. They also suggest that the gut microbiota at age two, while strongly influenced by diet, does not harbor obesity signatures many researchers identified in later life stages.

Acid suppressant medications and the risk of allergic diseases

INTRODUCTION

Acid suppressant medications (ASMs), such as proton pump inhibitors and histamine-2 receptor antagonists, are used often and throughout the lifespan. These medications have been linked to the development of a variety of allergic diseases. Areas covered: This review discusses prior studies investigating the association between acid ASM exposure and the development of allergic diseases. We performed a thorough literature search to identify potentially relevant studies for inclusion. In summary, exposure to these medications prenatally, in childhood and in adulthood, may increase the risk of allergic diseases. The current evidence is limited by primarily observational study design and potential bias and confounding. The mechanism of action is not yet known, but there are several proposed theories. Expert commentary: There is a growing body of evidence to support that exposure to acid ASMs increases the risk of developing allergic diseases. Further research is needed to not only clarify this relationship but to define the potential mechanism of action. If further research confirms these observations, we believe that could warrant changes in the patterns of prescribing and use of acid ASMs.

Diagnosis and Management of Gastroesophageal Reflux in Preterm Infants

Gastroesophageal reflux (GER), generally defined as the passage of gastric contents into the esophagus, is an almost universal phenomenon in preterm infants. It is a common diagnosis in the NICU; however, there is large variation in its treatment across NICU sites. In this clinical report, the physiology, diagnosis, and symptomatology in preterm infants as well as currently used treatment strategies in the NICU are examined. Conservative measures to control reflux, such as left lateral body position, head elevation, and feeding regimen manipulation, have not been shown to reduce clinically assessed signs of GER in the preterm infant. In addition, preterm infants with clinically diagnosed GER are often treated with pharmacologic agents; however, a lack of evidence of efficacy together with emerging evidence of significant harm (particularly with gastric acid blockade) strongly suggest that these agents should be used sparingly, if at all, in preterm infants.

Neonatal intestinal dysbiosis in necrotizing enterocolitis

Necrotizing Enterocolitis (NEC) is one of the most devastating gastrointestinal diseases in neonates, particularly among preterm infants in whom surgical NEC is the leading cause of morbidity. NEC pathophysiology occurs in the hyper-reactive milieu of the premature gut after bacterial colonization. The resultant activation of the TLR4 pathway appears to be a strongly contributing factor. Advancements in metagenomics may yield new clarity to the relationship between the neonatal intestinal microbiome and the development of NEC. After a century without effective directed treatments, microbiome manipulation offers a promising therapeutic target for the prevention and treatment of this devastating disease.

Acid Suppression for Gastroesophageal Reflux Disease in Infants

Gastroesophageal reflux is a normal physiologic occurrence that is common throughout infancy and usually resolves on its own. Infrequently, reflux causes complications and turns into gastroesophageal reflux disease (GERD), which may warrant intervention. Available interventions vary in invasiveness and supporting data may be lacking for efficacy and safety. Nonpharmacologic interventions are first-line therapy for GERD in infants, whereas pharmacologic and surgical approaches are controversial. Efficacy data are limited for pharmacologic strategies for infantile GERD and safety data have demonstrated serious risks, especially in younger infants. Utilization of these medications should be approached cautiously in this population, if appropriate diagnostic techniques determine acid suppression could be beneficial. A robust monitoring plan with frequent reassessment of need for therapy may optimize benefit and minimize risk.

Impact of prematurity and nutrition on the developing gut microbiome and preterm infant growth

BACKGROUND

Identification of factors that influence the neonatal gut microbiome is urgently needed to guide clinical practices that support growth of healthy preterm infants. Here, we examined the influence of nutrition and common practices on the gut microbiota and growth in a cohort of preterm infants.

RESULTS

With weekly gut microbiota samples spanning postmenstrual age (PMA) 24 to 46 weeks, we developed two models to test associations between the microbiota, nutrition and growth: a categorical model with three successive microbiota phases (P1, P2, and P3) and a model with two periods (early and late PMA) defined by microbiota composition and PMA, respectively. The more significant associations with phase led us to use a phase-based framework for the majority of our analyses. Phase transitions were characterized by rapid shifts in the microbiota, with transition out of P1 occurring nearly simultaneously with the change from meconium to normal stool. The rate of phase progression was positively associated with gestational age at birth, and delayed transition to a P3 microbiota was associated with growth failure. We found distinct bacterial metabolic functions in P1-3 and significant associations between nutrition, microbiota phase, and infant growth.

CONCLUSION

The phase-dependent impact of nutrition on infant growth along with phase-specific metabolic functions suggests a pioneering potential for improving growth outcomes by tailoring nutrient intake to microbiota phase.