Neonatal necrotizing enterocolitis: an update

Necrotizing enterocolitis: current understanding of the prevention and management

Necrotizing enterocolitis (NEC) is one of the diseases in neonates, with a high morbidity and mortality rate, especially in preterm infants. This review aimed to briefly introduce the latest epidemiology, susceptibility factors, and clinical diagnosis and presentation of NEC. We also organized new prevention strategies by risk factors according to different pathogeneses and then discussed new treatment methods based on Bell's staging and complications, and the classification of mild to high severity based on clinical and imaging manifestations. Such a generalization will help clinicians and researchers to gain a deeper understanding of the disease and to conduct more targeted classification, grading prevention, and exploration. We focused on prevention and treatment of the early and suspected stages of NEC, including the discovery of novel biomarkers and drugs to control disease progression. At the same time, we discussed its clinical application, future development, and shortcomings.

Abnormal Vaginal Flora in Cervical Incompetence Patients - the Impact of Escherichia coli

The purpose of this study was to investigate the prevalence of abnormal vaginal colonization in women with cervical incompetence and to analyze its impact on obstetric and neonatal outcomes and placental inflammation. We included 138 pregnant women diagnosed with cervical incompetence and delivered in our hospital. Patients with major fetal anomaly or multifetal pregnancy were excluded. Upper vaginal culture was performed on the day of admission. A total of 60.9% (84/138) of cervical incompetence patients had abnormal bacterial colonization, and Escherichia coli (E. coli) was the most common colonized pathogen (33.3%, 46/138). The positive vaginal E. coli group had a higher rate of prior preterm birth (p = 0.021) and an earlier gestational age at which cervical incompetence was diagnosed (p < 0.01) than the negative group. The positive vaginal E. coli group had higher rates of clinical chorioamnionitis (p = 0.008) and subchorionic microabscess of the placenta (p = 0.012). Importantly, the positive vaginal E. coli group had significantly higher rates of proven early-onset neonatal sepsis (EONS) (p = 0.046), necrotizing enterocolitis (NEC) (p = 0.001), and neonatal mortality (p = 0.023). After adjusting for confounding variables, the positive vaginal E. coli group had significantly higher risk for proven EONS (OR: 3.853, 95% CI: 1.056-14.055) and NEC (OR: 12.410, 95% CI: 1.290-119.351). In conclusion, E. coli was the most common vaginal microorganism isolated from patients with cervical incompetence. Maternal vaginal E. coli colonization was associated with adverse neonatal outcomes including proven EONS and NEC and was characterized by a higher rate of placental subchorionic microabscess.

Antimicrobial Peptides in Early-Life Host Defense, Perinatal Infections, and Necrotizing Enterocolitis—An Update

Host defense against early-life infections such as chorioamnionitis, neonatal sepsis, or necrotizing enterocolitis (NEC) relies primarily on innate immunity, in which antimicrobial peptides (AMPs) play a major role. AMPs that are important for the fetus and neonate include α and β defensins, cathelicidin LL-37, antiproteases (elafin, SLPI), and hepcidin. They can be produced by the fetus or neonate, the placenta, chorioamniotic membranes, recruited neutrophils, and milk-protein ingestion or proteolysis. They possess antimicrobial, immunomodulating, inflammation-regulating, and tissue-repairing properties. AMPs are expressed as early as the 13th week and increase progressively through gestation. Limited studies are available on AMP expression and levels in the fetus and neonate. Nevertheless, existing evidence supports the role of AMPs in pathogenesis of chorioamnionitis, neonatal sepsis, and NEC, and their association with disease severity. This suggests a potential role of AMPs in diagnosis, prevention, prognosis, and treatment of sepsis and NEC. Herein, we present an overview of the antimicrobial and immunomodulating properties of human AMPs, their sources in the intrauterine environment, fetus, and neonate, and their changes during pre- and post-natal infections and NEC. We also discuss emerging data regarding the potential utility of AMPs in early-life infections, as diagnostic or predictive biomarkers and as therapeutic alternatives or adjuncts to antibiotic therapy considering the increase of antibiotic resistance in neonatal intensive care units.

Providing the Best Parenteral Nutrition before and after Surgery for NEC: Macro and Micronutrients Intakes

Necrotizing enterocolitis (NEC) is the main gastrointestinal emergency of preterm infants for whom bowel rest and parenteral nutrition (PN) is essential. Despite the improvements in neonatal care, the incidence of NEC remains high (11% in preterm newborns with a birth weight <1500 g) and up to 20−50% of cases still require surgery. In this narrative review, we report how to optimize PN in severe NEC requiring surgery. PN should begin as soon as possible in the acute phase: close fluid monitoring is advocated to maintain volemia, however fluid overload and electrolytes abnormalities should be prevented. Macronutrients intake (protein, glucose, and lipids) should be adequately guaranteed and is essential in each phase of the disease. Composite lipid emulsion should be the first choice to reduce the risk of parenteral nutrition associated liver disease (PNALD). Vitamin and trace elements deficiency or overload are frequent in long-term PN, therefore careful monitoring should be planned starting from the recovery phase to adjust their parenteral intake. Neonatologists must be aware of the role of nutrition especially in patients requiring long-term PN to sustain growth, limiting possible adverse effects and long-term deficiencies.

Analysis of Factors Influencing Outcomes in Preterm Infants With Necrotizing Enterocolitis

BACKGROUND

To explore the surgical outcomes between patients with perforated and non-perforated neonatal necrotizing enterocolitis (NEC) and identify indications for surgical intervention.

METHODS

The surgical outcomes of 271 children with NEC admitted to the Seventh Medical Center of Chinese PLA General Hospital between August 2009 and August 2020 were retrospectively analyzed. The patients were divided into the non-perforated and perforated groups. The preoperative factors, including gestational age, birth weight, intrauterine infection, cholestasis, platelet change, white blood cell count, and C-reactive protein level were compared between the two groups, along with postoperative factors including infection status, complications, enteral and parenteral nutrition time, ICU time, ventilator use time, and intestinal necrosis length. Bell staging was performed for the two groups and the mortality of different Bell stages was explored. The risk of death and predisposing factors of patients with NEC were analyzed.

RESULTS

In total, 271 children undergoing surgery were included in this study. A total of 188 children were observed without perforation, including 57 deaths (30.3%), and 83 children with perforation, including 24 deaths (28.9%). Preoperative cholestasis and time from NEC diagnosis to surgery were significantly different between the two groups (P < 0.05). Postoperative factors, including parenteral nutrition time (32 [3-94] days vs. 23 [1-53] days), enteral nutrition time (27 [0-86] days vs. 18 [0-81] days), NICU time (44 [5-125] days vs. 29 [1-92] days), and length of intestinal necrosis (15 [0-92] cm vs. 10 [2-70] cm), were significant. The mortality rate of patients with Bell stage IIIA was higher than that of patients with Bell stage IIIB. A total of 81 patients had 30-day postoperative mortality (57 non-perforated cases). Multivariate Cox regression analysis showed that non-perforation was a poor prognostic factor for survival outcome (hazard ratio 2.288, 95% confidence interval [1.329-3.940], P = 0.003).

CONCLUSIONS

Preterm infants in the non-perforated group had more serious complications and had a longer recovery time after surgery. Bell staging is not accurate in diagnosing severe NEC that needs surgical intervention.

Necrotizing enterocolitis in the preterm: newborns medical and nutritional Management in a Single-Center Study

Necrotizing enterocolitis (NEC) is a typical disorder of preterm newborns, with a high mortality and morbidity rate. The therapeutic and nutritional management of disease depends on several factors. Its prognosis is linked, in addition to the severity of the disease and the need for surgery, to a correct enteral feeding in these patients. This study aims to identify the clinical characteristics of 18 patients with NEC, evaluating the different therapeutic paths undertaken, the type of formula used and the survival rate of this population. Average time of enteral nutrition before the NEC onset was 11,3 ± 11,6 days, with an average fasting period since the onset of 24 ± 18.9 days. 77.8% of patients received surgery and resumed enteral nutrition 17.7 ± 17.9 days after the intervention. The overall survival rate of our cohort was 55.5%. More prospective studies are needed to evaluate the long-term outcomes of survived children with NEC.

The Impact of Oral Sodium Chloride Supplementation on Thrive and the Intestinal Microbiome in Neonates With Small Bowel Ostomies: A Prospective Cohort Study

Background: Infants with ileostomies often suffer from sodium depletion, ultimately leading to a failure to thrive. Moreover, early-infantile microbial dysbiosis may potentially aggravate weight faltering. Given that sodium supplementation has been used to restore weight gain and feeding practices largely determine infantile microbiota, the current study investigated the effect of sodium chloride (NaCl) on weight gain and intestinal microbiome in infants with jejuno- and ileostomies.

Methods: A prospective cohort study including 24 neonates with enterostomies compared 19 subjects receiving oral NaCl (5.85%) to five subjects without supplementation with respect to postoperative changes in thrive and the intestinal microbiome.

Results: Infants receiving NaCl after enterostomy-surgery showed vastly improved weight gain and an increased abundance of Lactobacillus in fecal samples, as compared to subjects without oral supplement who displayed decreasing percentiles for weight and did not reveal a higher abundance of probiotic strains within the ostomy effluent. Contrarily, Klebsiella was equally enriched in supplemented infants, reflecting a higher susceptibility for infections in preterm neonates.

Discussion: Our findings support oral NaCl supplementation as a mainstay of postoperative treatment in infants with small bowel ostomies who are predisposed to suffer from a sodium depletion-associated failure to thrive. Not only does NaCl promote weight gain by increasing glucose resorption, but it also appears to induce microbial restoration by enhancing the abundance of health-promoting probiotic bacteria. This finding has an even greater significance when facing an elevated Klebsiella/Bifidobacteria (K/B) ratio, believed to represent an early-life microbial biomarker for development of allergic disease.

Use of intestine-related biomarkers for detecting intestinal epithelial damage in neonatal calves with diarrhea

OBJECTIVE

To evaluate the usefulness of intestinal biomarkers in determining the presence of intestinal epithelial damage in neonatal calves with diarrhea caused by 4 etiologic agents.

ANIMALS

40 neonatal calves that were healthy (n = 10) or had diarrhea (30).

PROCEDURES

The study was a cross-sectional study. Results of hematologic analyses and serum concentrations of intestinal fatty acid-binding protein (I-FABP), liver fatty acid-binding protein (L-FABP), trefoil factor 3 (TFF-3), Claudin-3 (CLDN-3), γ-enteric smooth muscle actin (ACTG2), intestinal alkaline phosphatase (IAP), interleukin-8 (IL-8), platelet-activating factor (PAF), and leptin (LP) were compared among calves grouped according to whether they were healthy (control group; G-1) or had diarrhea caused by K99 Escherichia coli (G-2; n = 10), bovine rota- or coronavirus (G-3; 5 each), or Cryptosporidium spp (G-4; 10).

RESULTS

Across the 3 time points at which blood samples were obtained and evaluated, the groups of calves with diarrhea generally had markedly higher mean serum concentrations of L-FABP, TFF-3, IAP, IL-8, and LP, compared with the control group. In addition, G-2 also consistently had markedly higher mean serum concentrations of I-FAB and ACTG2 and lower mean serum concentrations of CLDN-3, compared with the control group.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that degree of intestinal epithelial damage differed among calves grouped by the etiologic agent of diarrhea and that such damage might have been more severe in calves with diarrhea caused by K99 E coli. Additionally, our results indicated that serum concentrations of I-FABP, L-FABP, TFF-3, IAP, IL-8, ACTG2, LP, and CLDN-3 were useful biomarkers of intestinal epithelial damage in calves of the present study.

Calcium/calmodulin-dependent protein kinase IV signaling pathway is upregulated in experimental necrotizing enterocolitis

PURPOSE

Activation of calcium/calmodulin-dependent protein kinase IV (CaMKIV) has been shown to increase intestinal injury and inhibit epithelial cell proliferation in dextran sulfate sodium (DSS)-induced colitis mice. However, the role of CaMKIV in necrotizing enterocolitis (NEC) is unknown. We aimed to study the expression and activation of CaMKIV in experimental NEC.

METHODS

Following ethical approval, NEC (n = 10) was induced in C57BL/6 mouse pups by hypoxia, gavage hyperosmolar formula feeding and lipopolysaccharide from postnatal days P5 to 9. Breastfed pups served as control (n = 10). Mouse pups were sacrificed on P9 and the terminal ileum was harvested. Gene NEC injury was scored blindly by three independent investigators. CaMKIV, CREM and IL17 gene expression, and CaMKIV and pCaMKIV protein expression were assessed. The data were compared using Mann-Whitney U test. P < 0.05 was considered significant.

RESULTS

Intestinal injury was induced in the NEC mice and confirmed by histological scoring and inflammatory cytokine IL6. CaMKIV and its downstream target genes of CREM and IL17 were significantly elevated in NEC mice relative to control. Similarly, phosphorylated-CaMKIV (pCaMKIV), the active form of CaMKIV, was more notably expressed in the NEC ileal tissue relative to control ileal tissue. Elevated pCaMKIV protein expression was also confirmed by western blot.

CONCLUSION

CaMKIV expression and activation are upregulated in experimental NEC suggesting a potential contributing factor in the pathogenesis of NEC.

Nutrition in Necrotizing Enterocolitis and Following Intestinal Resection

This review aims to discuss the role of nutrition and feeding practices in necrotizing enterocolitis (NEC), NEC prevention, and its complications, including surgical treatment. A thorough PubMed search was performed with a focus on meta-analyses and randomized controlled trials when available. There are several variables in nutrition and the feeding of preterm infants with the intention of preventing necrotizing enterocolitis (NEC). Starting feeds later rather than earlier, advancing feeds slowly and continuous feeds have not been shown to prevent NEC and breast milk remains the only effective prevention strategy. The lack of medical treatment options for NEC often leads to disease progression requiring surgical resection. Following resection, intestinal adaptation occurs, during which villi lengthen and crypts deepen to increase the functional capacity of remaining bowel. The effect of macronutrients on intestinal adaptation has been extensively studied in animal models. Clinically, the length and portion of intestine that is resected may lead to patients requiring parenteral nutrition, which is also reviewed here. There remain significant gaps in knowledge surrounding many of the nutritional aspects of NEC and more research is needed to determine optimal feeding approaches to prevent NEC, particularly in infants younger than 28 weeks and <1000 grams. Additional research is also needed to identify biomarkers reflecting intestinal recovery following NEC diagnosis individualize when feedings should be safely resumed for each patient.

Necrotizing Enterocolitis in Moderate Preterm Infants

Necrotizing enterocolitis (NEC) is a devastating morbidity usually seen in preterm infants, with extremely preterm neonates (EPT ≤28 weeks) considered at highest risk. Moderately preterm infants (MPT 28-34 weeks) constitute a large percentage of NICU admissions. In our retrospective data analysis of NEC in a single regional perinatal center, NEC was observed in 10% of extremely EPT and 7% of MPT, but only 0.7% of late-preterm/term admissions. There was an inverse relationship between postnatal age at onset of NEC and gestational age at birth. Among MPT infants with NEC, maternal hypertensive disorders (29%) and small for gestational age (SGA-15%) were more common than in EPT infants (11.6 and 4.6%, resp.). Congenital gastrointestinal anomalies were common among late preterm/term infants with NEC. SGA MPT infants born to mothers with hypertensive disorders are particularly at risk and should be closely monitored for signs of NEC. Identifying risk factors specific to each gestational age may help clinicians to tailor interventions to prevent NEC.

Human Milk Oligosaccharides in the Prevention of Necrotizing Enterocolitis: A Journey From in vitro and in vivo Models to Mother-Infant Cohort Studies

Preterm infants who receive human milk instead of formula are 6- to 10-times less likely to develop necrotizing enterocolitis (NEC), one of the most common and devastating intestinal disorders that affects 5-10% of all very-low-birth-weight infants. Combined data from in vitro tissue culture models, in vivo preclinical studies in animal models, as well human mother-infant cohort studies support the hypothesis that human milk oligosaccharides (HMOs), complex sugars that are highly abundant in human milk but not in infant formula, contribute to the beneficial effects of human milk feeding in reducing NEC. The almost 20-year long journey of testing this hypothesis took an interesting turn during HMO in vivo efficacy testing and structure elucidation, suggesting that the original hypothesis may indeed be correct and specific HMO reduce NEC risk, however, the underlying mechanisms are likely different than originally postulated.

IL-17 in neonatal health and disease

Over the last few years, scientific interest in the cytokine IL-17A has intensified as its role in human health and disease has been elucidated. Discovered almost a quarter century ago, IL-17A is known to have poor biologic activity when acting alone, but attains robust actions when working synergistically with potent mediators of proinflammatory immune responses, such as IL-6 and IL-8. IL-17A is produced by specialized innate immune cells that protect host barriers from the outside world. Like sentries, these innate immune cells can "sound the alarm" through increased production of IL-17A, causing activation and recruitment of primed neutrophils and monocytes when pathogens escape initial host defenses. In this way, IL-17A promulgates mechanisms responsible for pathogen death and clearance. However, when IL-17A pathways are triggered during fetal development, due to chorioamnionitis or in utero inflammatory conditions, IL-17A can instigate and/or exacerbate fetal inflammatory responses that increase neonatal morbidities and mortality associated with common neonatal conditions such as sepsis, bronchopulmonary dysplasia (BPD), patent ductus arteriosus (PDA), and necrotizing enterocolitis (NEC). This review details the ontogeny of IL-17A in the fetus and newborn, discusses how derangements in its production can lead to pathology, and describes known and evolving therapies that may attenuate IL-17A-mediated human conditions.

Idiopathic neonatal pneumoperitoneum, a case report

INTRODUCTION

There have been non-surgical conditions secondary to neonatal pneumoperitoneum (e.g., mechanical ventilation, pulmonary diseases and pneumatosis cystoides intestinalis) that neonates were able to overcome without the need for abdominal exploration. Idiopathic pneumoperitoneum, although similar to perforation of the alimentary tract and the previously mentioned non-surgical conditions, is a rare and benign condition that does not yet have a definite cause. The criteria by which a surgeon decides on which abdomen to open and which one to observe, is ill-defined. Thus, increasing the awareness of neonatologists and surgeons about this condition will help decrease complications due to unnecessary procedures.

PRESENTATION OF THE CASE

We report a case of a neonate with a massive pneumoperitoneum who obtained a surgical intervention with negative finding. We had noted that the bag of the abdominal drain was expanded with gas every 2days, we replace the bag by new one every 2days for 10days postoperative. Nonetheless, the cause of pneumoperitoneum remains unclear.

DISCUSSION

There are five main nonsurgical causes of free air in the peritoneal cavity. These are categorized as follow: pseudopneumoperitoneum, thoracic, abdominal, gynecological and idiopathic. This is a condition in which imaging shows free air in the peritoneal cavity that can either be managed with observation and supportive care alone or results in a negative laparotomy.

CONCLUSION

This case demonstrated that laparotomy is not a true routine in neonates with idiopathic pneumoperitoneum if a timely diagnosis is established. Future research is still necessary to understand the source of the free gas in the abdomen, as well as the underlying causes of delayed postoperative gas underdiaphragm and postoperative abdominal drain bag gas expansion.

Pathogenesis of NEC: Role of the innate and adaptive immune response

Necrotizing enterocolitis (NEC) is a devastating disease in premature infants with high case fatality and significant morbidity among survivors. Immaturity of intestinal host defenses predisposes the premature infant gut to injury. An abnormal bacterial colonization pattern with a deficiency of commensal bacteria may lead to a further breakdown of these host defense mechanisms, predisposing the infant to NEC. Here, we review the role of the innate and adaptive immune system in the pathophysiology of NEC.

Intestinal Failure in Children

Children with intestinal failure have had improved survival, particularly those with extreme short bowel syndrome, over the last 10-15 y. This has been attributed to better understanding of the pathophysiology of intestinal failure, improvement in line care, recognition of the importance of a team approach as well as the progress of intestinal transplant as a viable option. Parenteral nutrition remains the cornerstone for the continual survival of these patients. This review will cover contemporary approaches to intestinal failure including post surgical approaches, non-transplant surgery, dietetic and medication approaches during the adaptation process, considerations for home parenteral nutrition and latest in intestinal transplantation.

Barriers to Knowledge Translation Regarding the Use of Probiotics as a Risk-Reduction Strategy for Necrotizing Enterocolitis

BACKGROUND

Increasingly, evidence supports enteral probiotics are an important risk-reduction strategy for necrotizing enterocolitis (NEC) among very low birth-weight and extremely low birth-weight preterm infants. Yet, the majority of providers remain reluctant to implement practice changes.

PURPOSE

The aim of this study was to better understand the discrepancy between the available evidence and clinical practice regarding the use of probiotics and other NEC prevention strategies in New Jersey.

METHODS

Using an exploratory descriptive design, a multimodal interprofessional survey was developed and executed to elicit intensive care nursery provider knowledge, views, and current practice.

RESULTS

Although the sample size was small (N = 29), approximately one-half of respondents familiar with the literature rated the quality of the evidence regarding probiotics as "above average" to "excellent." These respondents were "very likely" to "extremely likely" to recommend probiotics as an NEC prevention strategy; however, none actually prescribed this intervention. The most important reason respondents did not prescribe probiotics was the focus on providing exclusive maternal and donor breast milk feedings. Other confounding factors included provision of oral colostrum care, standardized feeding protocols, and withholding feedings during blood transfusion.

IMPLICATIONS FOR PRACTICE

Study results suggested that some providers (primarily nurses) were not familiar with probiotic literature, which may contribute to deficits in knowledge translation to practice.

IMPLICATIONS FOR RESEARCH

Areas for future study include identifying improved mechanisms for knowledge dissemination, recognizing and addressing barriers and facilitators to knowledge translation, and understanding how probiotics fit and/or contrast with other NEC risk-reduction strategies in the research and clinical settings.

Fetal and postnatal ovine mesenteric vascular reactivity

BACKGROUND

Intestinal circulation and mesenteric arterial (MA) reactivity may play a role in preparing the fetus for enteral nutrition. We hypothesized that MA vasoreactivity changes with gestation and vasodilator pathways predominate in the postnatal period.

METHODS

Small distal MA rings (0.5-mm diameter) were isolated from fetal (116-d, 128-d, 134-d, and 141-d gestation, term ~ 147 d) and postnatal lambs. Vasoreactivity was evaluated using vasoconstrictors (norepinephrine (NE) after pretreatment with propranolol and endothelin-1(ET-1)) and vasodilators (NO donors A23187 and s-nitrosopenicillamine (SNAP)). Protein and mRNA assays for receptors and enzymes (endothelin receptor A, alpha-adrenergic receptor 1A (ADRA1A), endothelial NO synthase (eNOS), soluble guanylyl cyclase (sGC), and phosphodiesterase5 (PDE5)) were performed in mesenteric arteries.

RESULTS

MA constriction to NE and ET-1 peaked at 134 d. Relaxation to A23187 and SNAP was maximal after birth. Basal eNOS activity was low at 134 d. ADRA1A mRNA and protein increased significantly at 134 d and decreased postnatally. sGC and PDE5 protein increased from 134 to 141 d.

CONCLUSION

Mesenteric vasoconstriction predominates in late-preterm gestation (134 d; the postconceptional age with the highest incidence of necrotizing enterocolitis (NEC)) followed by a conversion to vasodilatory influences near the time of full-term birth. Perturbations in this ontogenic mechanism, including preterm birth, may be a risk factor for NEC.

Usefulness of ultrasound examinations in the diagnostics of necrotizing enterocolitis

Background

Necrotizing enterocolitis (NEC) is one of the most serious disorders of gastrointestinal tract during neonatal period. Early diagnosis and adequate treatment are essential in the presence of clinical suspicion of NEC. Plain abdominal radiography is currently the modality of choice for initial evaluation of gastrointestinal tract in neonates. However, when the diagnosis is uncertain, abdominal ultrasound with bowel assessment might be an important complementary examination. The aim of the study was to evaluate usefulness of ultrasound in the diagnosis of NEC and its value for implementation of proper treatment.

Material/Methods

The data of nine neonates diagnosed with NEC, hospitalized at the Provincial Hospital No. 2 in Rzeszow in the period from September 2009 to April 2013 was retrospectively analyzed. Apart from abdominal radiography, abdominal ultrasound with bowel assessment was performed in all nine cases. Imaging findings, epidemiological data, coexisting risk factors and disease course were assessed.

Results

Most children in the group were preterm neonates. Findings in plain abdominal radiography were normal or nonspecific. A wider spectrum of findings was demonstrated in all ultrasound examinations and intestinal pneumatosis, a pathognomonic sign for NEC, was more frequently noted than in plain abdominal x-ray. Most children were treated by surgical intervention with resection of necrotic bowel loops and in more than half of the cases location of changes identified during surgery was concordant with ultrasonographic findings.

Conclusions

Abdominal ultrasound examination might be helpful in the diagnosis of NEC, especially when plain abdominal radiography findings do not correlate with clinical symptoms. However, abdominal radiography is still considered the modality of choice. The range of morphological changes detectable on ultrasound examination is much wider than in plain abdominal radiography. Ultrasound examination allows for more accurate assessment of changes within intestines and adjacent tissues, which aids clinicians in making more accurate therapeutic decisions and implementing proper treatment.

Necrotizing enterocolitis in newborns: update in pathophysiology and newly emerging therapeutic strategies

While the survival of extremely premature infants with respiratory distress syndrome has increased due to advanced respiratory care in recent years, necrotizing enterocolitis (NEC) remains the leading cause of neonatal mortality and morbidity. NEC is more prevalent in lower gestational age and lower birth weight groups. It is characterized by various degrees of mucosal or transmural necrosis of the intestine. Its exact pathogenesis remains unclear, but prematurity, enteral feeding, bacterial products, and intestinal ischemia have all been shown to cause activation of the inflammatory cascade, which is known as the final common pathway of intestinal injury. Awareness of the risk factors for NEC; practices to reduce the risk, including early trophic feeding with breast milk and following the established feeding guidelines; and administration of probiotics have been shown to reduce the incidence of NEC. Despite advancements in the knowledge and understanding of the pathophysiology of NEC, there is currently no universal prevention measure for this serious and often fatal disease. Therefore, new potential techniques to detect early biomarkers or factors specific to intestinal inflammation, as well as further strategies to prevent the activation of the inflammatory cascade, which is important for disease progression, should be investigated.

Probiotics and necrotizing enterocolitis

One of the most controversial areas in neonatology is whether probiotics should be provided routinely to preterm infants to prevent necrotizing enterocolitis (NEC). This review provides the reader with a brief overview of NEC and current concepts of its pathophysiology, discusses the microbial ecology of the intestine in preterm infants and factors that may lead to a "dysbiosis", summarizes studies of probiotics in preterm infants, elaborates on the need for regulation in this area, and discusses alternatives to probiotics and what is the future for the prevention of NEC.

Intestinal proteomics in pig models of necrotising enterocolitis, short bowel syndrome and intrauterine growth restriction

Necrotising enterocolitis (NEC), short bowel syndrome (SBS) and intrauterine growth restriction (IUGR) are three conditions associated with intestinal dysfunction in newborn infants, particularly those born preterm. Piglet (Sus scrofa) models have recently been developed for NEC, SBS and IUGR, and tissue proteomic analyses have identified unknown pathways and new prognostic disease markers. Intestinal HSPs, iron metabolism proteins and proteins related to amino acid (e.g. arginine) and glucose metabolism are consistently affected by NEC progression and some of these proteins are also affected by SBS and IUGR. Parallel changes in some plasma and urinary proteins (e.g. haptoglobin, globulins, complement proteins, fatty acid binding proteins) may mirror the intestinal responses and pave the way to biomarker discovery. Explorative non-targeted proteomics provides ideas about the cellular pathways involved in intestinal adaptation during the critical neonatal period. Proteomics, combined with other -omic techniques, helps to get a more holistic picture of intestinal adaptation during NEC, SBS and IUGR. Explorative -omic research methods also have limitations and cannot replace, but only supplement, classical hypothesis-driven research that investigate disease mechanisms using a single or few endpoints.

Small intestinal intraepithelial TCRγδ+ T lymphocytes are present in the premature intestine but selectively reduced in surgical necrotizing enterocolitis

BACKGROUND

Gastrointestinal barrier immaturity predisposes preterm infants to necrotizing enterocolitis (NEC). Intraepithelial lymphocytes (IEL) bearing the unconventional T cell receptor (TCR) γδ (γδ IEL) maintain intestinal integrity and prevent bacterial translocation in part through production of interleukin (IL) 17.

OBJECTIVE

We sought to study the development of γδ IEL in the ileum of human infants and examine their role in NEC pathogenesis. We defined the ontogeny of γδ IEL proportions in murine and human intestine and subjected tcrδ-/- mice to experimental gut injury. In addition, we used polychromatic flow cytometry to calculate percentages of viable IEL (defined as CD3+ CD8+ CD103+ lymphocytes) and the fraction of γδ IEL in surgically resected tissue from infants with NEC and gestational age matched non-NEC surgical controls.

RESULTS

In human preterm infants, the proportion of IEL was reduced by 66% in 11 NEC ileum resections compared to 30 non-NEC controls (p<0.001). While γδ IEL dominated over conventional αβ IEL early in gestation in mice and in humans, γδ IEL were preferential decreased in the ileum of surgical NEC patients compared to non-NEC controls (50% reduction, p<0.05). Loss of IEL in human NEC was associated with downregulation of the Th17 transcription factor retinoic acid-related orphan nuclear hormone receptor C (RORC, p<0.001). TCRδ-deficient mice showed increased severity of experimental gut injury (p<0.05) with higher TNFα expression but downregulation of IL17A.

CONCLUSION

Complimentary mouse and human data suggest a role of γδ IEL in IL17 production and intestinal barrier production early in life. Specific loss of the γδ IEL fraction may contribute to NEC pathogenesis. Nutritional or pharmacological interventions to support γδ IEL maintenance in the developing small intestine could serve as novel strategies for NEC prevention.

Evidence-based feeding strategies before and after the development of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating disease of premature infants and is associated with significant morbidity and mortality. While the pathogenesis of NEC remains incompletely understood, it is well established that the risk of disease is increased by the administration of infant formula and decreased by the administration of breast milk. This review will focus on the mechanisms by which breast milk may serve to protect against NEC, and will review the evidence regarding various feeding strategies that may be utilized before and after an episode of NEC.

Necrotising enterocolitis in preterm infants: epidemiology and antibiotic consumption in the Polish neonatology network neonatal intensive care units in 2009

The aim of this study was to describe the epidemiology of necrotising enterocolitis (NEC), antibiotic consumption and the usefulness of microbiological tests in very low birth weight (VLBW) Polish newborns.

METHODS

Prospective surveillance was performed in the year 2009 by local infection control teams. The study covered 910 infants hospitalized in six Polish neonatal intensive care units. Two kinds of indicators were used for the description of antibiotic usage: the duration of treatment (days of treatment, DOTs) and the defined daily dose (DDD).

RESULTS

NEC incidence was 8.7% and fatality rate was 19%. Chorioamnionitis, late gestational age and low birth weight were identified as risk factors for NEC. Catheterization, mechanical ventilation and other selected procedures were used considerably longer in newborns with NEC than in the remaining neonates. Total usage of antibiotics reached 2.9 DDDs or 1.437 days; the average use of drugs per case of NEC amounted to 0.47 DDD or 23.2 DOTs. The level of antibiotic usage was analysed with correlation to microbiological tests performed and it was non-significantly greater in the group of children with NEC in whom the tests were performed.

CONCLUSIONS

A high risk of developing NEC is closely associated with VLBW and with inflammation of the amnion during labour. We observed no relationship between the consumption of antibiotics in neonates with NEC and positive results of microbiological testing indicating sepsis accompanying NEC or gut colonization with pathogens.

Commensal and probiotic bacteria may prevent NEC by maturing intestinal host defenses

Necrotizing enterocolitis (NEC) is a devastating disease of prematurity with significant morbidity and mortality. Immaturity of intestinal host defenses predisposes the premature infant gut to injury. An abnormal bacterial colonization pattern with a deficiency of commensal bacteria may lead to a further breakdown of these host defense mechanisms, predisposing the infant to NEC. The presence of probiotic and commensal bacteria within the gut has been shown to mature the intestinal defense system through a variety of mechanisms. We have shown that commensal and probiotic bacteria can promote intestinal host defenses by reducing apoptotic signaling, blocking inflammatory signaling, and maturing barrier function in immature intestinal epithelia. Future studies aimed at elucidating the mechanisms by which probiotic and commensal bacteria exert their effects will be critical to developing effective preventive therapies for NEC.

Packed red cell transfusions alter mesenteric arterial reactivity and nitric oxide pathway in preterm lambs

BACKGROUND

Cases of necrotizing enterocolitis occurring within 48 h of packed red blood cell (PRBC) transfusions are increasingly being described in observational studies. Transfusion-associated gut injury is speculated to result from an abnormal mesenteric vascular response to transfusion. However, the mechanism of disruption of the balance between mesenteric vasoconstriction and relaxation following transfusion is not known.

METHODS

Preterm lambs (n = 16, 134 d gestation; term: 145-147 d) were delivered and ventilated for 24 h. All the lambs received orogastric feeds with colostrum. In addition, 10 of these lambs received PRBC transfusions. Vasoreactivity was evaluated in isolated mesenteric arterial rings using norepinephrine and endothelin-1 as vasoconstrictors. Endothelium-dependent (A23187, a calcium ionophore) and endothelium-independent (SNAP) nitric oxide (NO) donors were used as vasorelaxants. Mesenteric arterial endothelial NO synthase (eNOS), soluble guanylyl cyclase (sGC), and phosphodiesterase 5 (PDE5) mRNA analyses and protein assays were performed.

RESULTS

Transfusion with PRBC significantly increased mesenteric vasoconstriction to norepinephrine and endothelin-1 and impaired relaxation to A23187 and SNAP. Mesenteric arterial eNOS protein decreased following PRBC transfusion. No significant changes were noted in sGC and PDE5 mRNA or protein assays.

CONCLUSION

PRBC transfusion in enterally fed preterm lambs promotes mesenteric vasoconstriction and impairs vasorelaxation by reducing mesenteric arterial eNOS.

Analysis of the association between necrotizing enterocolitis and transfusion of red blood cell in very low birth weight preterm infants

Purpose

To investigate the association between necrotizing enterocolitis (NEC) and red blood cell transfusions in very low birth weight (VLBW) preterm infants.

Methods

We studied were 180 VLBW preterm infants who were admitted to the neonatal intensive care unit of CHA Gangnam Hospital from January of 2006 to December of 2009. The subjects were divided into 2 groups: an NEC group (greater than stage II on the modified Bell's criteria) and a control group (less than stage II on the modified Bell's critieria). We defined red blood cell transfusion before NEC diagnosis as the frequency of transfusion until NEC diagnosis (mean day at NEC diagnosis, day 18) in the NEC group and the frequency of transfusion until 18 days after birth in the control group.

Results

Of the 180 subjects, 18 (10%) belonged to the NEC group, and 14 (78%) of these 18 patients had a history of transfusion before NEC diagnosis. The NEC group received 3.1±2.9 transfusions, and the control group received 1.0±1.1 transfusions before the NEC diagnosis (P=0.005). In a multivariate logistic regression corrected for gestational age, Apgar score at 1 minute, the presence of respiratory distress syndrome, patent ductus arteriosus, premature rupture of membrane, disseminated intravascular coagulopathy and death were confounding factors. The risk of NEC increased 1.63 times (95% confidence interval, 1.145 to 2.305; P=0.007) with transfusion before the NEC diagnosis.

Conclusion

The risk for NEC increased significantly with increased transfusion frequency before the NEC diagnosis.

A clinical perspective of necrotizing enterocolitis: past, present, and future

Necrotizing enterocolitis (NEC) primarily affects premature infants. It is less common in term and late preterm infants. The age of onset is inversely related to the postmenstrual age at birth. In term infants, NEC is commonly associated with congenital heart diseases. NEC has also been associated with other anomalies. More than 85% of all NEC cases occur in very low birth weight infants or in very premature infants. Despite incremental advances in our understanding of the clinical presentation and pathophysiology of NEC, universal prevention of this disease continues to elude us even in the twenty-first century.

Noninvasive measurement of intestinal epithelial damage at time of refeeding can predict clinical outcome after necrotizing enterocolitis

BACKGROUND

Reintroduction of enteral nutrition in neonates with necrotizing enterocolitis (NEC) should take place when the gut is ready for its normal function. Too early a start of oral feeding might lead to disease relapse, whereas prolonged discontinuation of enteral nutrition is associated with impaired gut function and parenteral nutrition-related complications. This study evaluated whether noninvasive urinary measurement of intestinal fatty acid binding protein (I-FABP) at the time of refeeding can predict clinical outcome in neonates with NEC.

METHODS

Urinary I-FABP concentrations were measured in 21 infants with NEC just before reintroducing enteral nutrition. Poor outcome was defined as unsuccessful reintroduction of enteral feeding (EF), (re)operation for NEC, or death related to NEC after reintroduction of EF.

RESULTS

Median urinary I-FABP levels in neonates with poor outcome (n = 5) were significantly higher as compared with I-FABP levels in neonates with good outcome (n = 16) (P < 0.01). A clinically significant cutoff value of 963 pg/ml was found to discriminate between infants with poor outcome and those with good outcome (sensitivity 80%, specificity 94%).

CONCLUSION

Noninvasive urinary I-FABP measurement at time of refeeding differentiates neonates with poor outcome from neonates with good outcome in NEC. Urinary I-FABP measurement may therefore be helpful in the timing of EF in neonates with NEC.

Carnitine deficiency in OCTN2-/- newborn mice leads to a severe gut and immune phenotype with widespread atrophy, apoptosis and a pro-inflammatory response

We have investigated the gross, microscopic and molecular effects of carnitine deficiency in the neonatal gut using a mouse model with a loss-of-function mutation in the OCTN2 (SLC22A5) carnitine transporter. The tissue carnitine content of neonatal homozygous (OCTN2^−/−) mouse small intestine was markedly reduced; the intestine displayed signs of stunted villous growth, early signs of inflammation, lymphocytic and macrophage infiltration and villous structure breakdown. Mitochondrial β-oxidation was active throughout the GI tract in wild type newborn mice as seen by expression of 6 key enzymes involved in β-oxidation of fatty acids and genes for these 6 enzymes were up-regulated in OCTN2^−/− mice. There was increased apoptosis in gut samples from OCTN2^−/− mice. OCTN2^−/− mice developed a severe immune phenotype, where the thymus, spleen and lymph nodes became atrophied secondary to increased apoptosis. Carnitine deficiency led to increased expression of CD45-B220⁺ lymphocytes with increased production of basal and anti-CD3-stimulated pro-inflammatory cytokines in immune cells. Real-time PCR array analysis in OCTN2^−/− mouse gut epithelium demonstrated down-regulation of TGF-β/BMP pathway genes. We conclude that carnitine plays a major role in neonatal OCTN2^−/− mouse gut development and differentiation, and that severe carnitine deficiency leads to increased apoptosis of enterocytes, villous atrophy, inflammation and gut injury.

Antibiotics increase gut metabolism and antioxidant proteins and decrease acute phase response and necrotizing enterocolitis in preterm neonates

Background

The appropriate use of antibiotics for preterm infants, which are highly susceptible to develop necrotizing enterocolitis (NEC), is not clear. While antibiotic therapy is commonly used in neonates with NEC symptoms and sepsis, it remains unknown how antibiotics may affect the intestine and NEC sensitivity. We hypothesized that broad-spectrum antibiotics, given immediately after preterm birth, would reduce NEC sensitivity and support intestinal protective mechanisms.

Methodology/Principal Findings

Preterm pigs were treated with antibiotics for 5 d (oral and systemic doses of gentamycin, ampicillin and metrodinazole; AB group) and compared with untreated pigs. Only the untreated pigs showed evidence of NEC lesions and reduced digestive function, as indicated by lowered villus height and activity of brush border enzymes. In addition, 53 intestinal and 22 plasma proteins differed in expression between AB and untreated pigs. AB treatment increased the abundance of intestinal proteins related to carbohydrate and protein metabolism, actin filaments, iron homeostasis and antioxidants. Further, heat shock proteins and the complement system were affected suggesting that all these proteins were involved in the colonization-dependent early onset of NEC. In plasma, acute phase proteins (haptoglobin, complement proteins) decreased, while albumin, cleaved C3, ficolin and transferrin increased.

Conclusions/Significance

Depressed bacterial colonization following AB treatment increases mucosal integrity and reduces bacteria-associated inflammatory responses in preterm neonates. The plasma proteins C3, ficolin, and transferrin are potential biomarkers of the colonization-dependent NEC progression in preterm neonates.

Cellular strain amplifies LPS-induced stress signaling in immature enterocytes: potential implications for preterm infant NCPAP

BACKGROUND

Recent clinical observations of increased necrotizing enterocolitis (NEC) incidence in some nasal continuous positive airway pressure (NCPAP) patients raise concerns about whether the related abdominal distension is benign or contributes to NEC. We tested the hypothesis that mechanical strain causes an exaggerated enterocyte inflammatory response and decreased enterocyte growth and proliferation in the absence and presence of lipopolysaccharide (LPS).

METHODS

First we used a confluent enterocyte (IEC-6) monolayer to investigate effects of strain on inflammatory cytokine production and Toll-like receptor 4 (TLR-4) gene expression. Then we used a low seeding density to measure cell growth and proliferation. Ten percent mechanical strain was applied.

RESULTS

Significant increases in interleukin (IL)-8 and in IL-6 were observed after 8 and 24 h of cellular strain, respectively, and maintained throughout the study. TLR-4 expression was increased at 48 h. Mechanical strain led to slower proliferation and division whereas LPS alone had minimal effects. The responses of LPS and strain were supra-additive, suggesting synergistic cellular effects.

CONCLUSION

We speculate intestinal distension associated with the use of NCPAP, especially in the presence of abnormal gut colonization, may result in increased inflammatory cytokine production and be a contributing factor to neonatal intestinal morbidities.

Investigation of the early intestinal microflora in premature infants with/without necrotizing enterocolitis using two different methods

INTRODUCTION

The pathophysiology of necrotizing enterocolitis (NEC) is multifactorial, and gastrointestinal bacteria are thought to play an important role. In this study, the role of microflora in the gastrointestinal tract of neonates with NEC was assessed by comparing cases with controls.

RESULTS

Of the 163 neonates, 21 developed NEC. The risk of NEC decreased by 8% with each additional day of gestational age.

DISCUSSION

Typically, very few bacterial species could be cultured from the fecal specimens obtained. Gram-positive (G(+)) bacteria dominated the samples in the NEC group, whereas in the control group mixed flora of G(+) and Gram-negative (G(-)) bacteria were isolated. Surprisingly, molecular analysis using PCR-DGGE profiles did not confirm these differences. Our data suggest that G(+) bacteria in the intestine may play a role in the development of NEC in premature infants.

METHODS

One hundred and sixty three neonates born at <30 weeks of gestation were enrolled. Fecal samples taken during the first month of life were subjected to culture and PCR-denaturing gradient gel electrophoresis (PCR-DGGE). A total of 482 fecal samples were examined.

Probiotic bacteria induce maturation of intestinal claudin 3 expression and barrier function

An immature intestinal epithelial barrier may predispose infants and children to many intestinal inflammatory diseases, such as infectious enteritis, inflammatory bowel disease, and necrotizing enterocolitis. Understanding the factors that regulate gut barrier maturation may yield insight into strategies to prevent these intestinal diseases. The claudin family of tight junction proteins plays an important role in regulating epithelial paracellular permeability. Previous reports demonstrate that rodent intestinal barrier function matures during the first 3 weeks of life. We show that murine paracellular permeability markedly decreases during postnatal maturation, with the most significant change occurring between 2 and 3 weeks. Here we report for the first time that commensal bacterial colonization induces intestinal barrier function maturation by promoting claudin 3 expression. Neonatal mice raised on antibiotics or lacking the toll-like receptor adaptor protein MyD88 exhibit impaired barrier function and decreased claudin 3 expression. Furthermore, enteral administration of either live or heat-killed preparations of the probiotic Lactobacillus rhamnosus GG accelerates intestinal barrier maturation and induces claudin 3 expression. However, live Lactobacillus rhamnosus GG increases mortality. Taken together, these results support a vital role for intestinal flora in the maturation of intestinal barrier function. Probiotics may prevent intestinal inflammatory diseases by regulating intestinal tight junction protein expression and barrier function. The use of heat-killed probiotics may provide therapeutic benefit while minimizing adverse effects.

Secreted factors from Bifidobacterium animalis subsp. lactis inhibit NF-κB-mediated interleukin-8 gene expression in Caco-2 cells

The objective of the present study was to evaluate the anti-inflammatory effects of Bifidobacterium animalis subsp. lactis strain BB12 in stimulated Caco-2 cells and to characterize the factors responsible for these anti-inflammatory effects. Characterization and purification studies indicate that BB12's anti-inflammatory factors might include a 50-kDa proteinaceous compound that is stable under a variety of heat and pH conditions.

Gene-expression profile analysis in the mid-gestation human intestine discloses greater functional immaturity of the colon as compared with the ileum

BACKGROUND AND OBJECTIVES

The occurrence of many neonatal inflammatory intestinal diseases in preterm infants highlights the susceptibility of the immature intestine to responding inadequately to nutrients and microbes. A better understanding of functional intestinal development is essential for the design of optimal treatments ensuring survival and growth of premature infants. The purpose of this study was to evaluate the gene expression profiles of the human ileum and colon at mid-gestation because these 2 segments are considered to be similar at this stage and are the sites of the most frequent pathologies in preterm infants.

SUBJECTS AND METHODS

We compared the gene-expression profiles of human fetal small and large intestines using a cDNA microarray and analyzed the data with Ingenuity Pathway Analysis software.

RESULTS

We found that a significant proportion of the genes was differentially expressed in the 2 segments. Gene cluster analysis revealed an even higher level of transcriptional dissimilarity at the functional level. For instance, segment-specific/overexpressed gene clusters in the ileum included genes involved with amino acid, vitamin, and mineral metabolism, reflecting the higher level of maturity of the small intestine as compared with the colon in which genes involved with cell cycle, cell death, and cell signaling were the predominant clusters of genes expressed.

CONCLUSIONS

Functional clustering analysis of the differentially expressed genes revealed important functional differences between the 2 segments and a relative immaturity of the colon, suggesting that already at mid-gestation, the 2 intestinal segments should be considered as 2 distinct organs.

Leucine supplementation of a low-protein meal increases skeletal muscle and visceral tissue protein synthesis in neonatal pigs by stimulating mTOR-dependent translation initiation

Protein synthesis and eukaryotic initiation factor (eIF) activation are increased in skeletal muscle of neonatal pigs parenterally infused with amino acids. Leucine appears to be the most effective single amino acid to trigger these effects. To examine the response to enteral leucine supplementation, overnight food-deprived 5-d-old pigs were gavage fed at 0 and 60 min a: 1) low-protein diet (LP); 2) LP supplemented with leucine (LP+L) to equal leucine in the high-protein diet (HP); or 3) HP diet. Diets were isocaloric and equal in lactose. Fractional protein synthesis rates and translation initiation control mechanisms were examined in skeletal muscles and visceral tissues 90 min after feeding. Protein synthesis rates in longissimus dorsi, gastrocnemius, and masseter muscles, heart, jejunum, kidney, and pancreas, but not liver, were greater in the LP+L group compared with the LP group and did not differ from the HP group. Feeding LP+L and HP diets compared with the LP diet increased phosphorylation of mammalian target of rapamycin (mTOR), 4E-binding protein 1, ribosomal protein S6 kinase-1, and eIF4G and formation of the active eIF4E·eIF4G complex in longissimus dorsi muscle. In all tissues except liver, activation of mTOR effectors increased in pigs fed LP+L and HP vs. LP diets. Our results suggest that leucine supplementation of a low-protein meal stimulates protein synthesis in muscle and most visceral tissues to a rate similar to that achieved by feeding a high-protein meal and this stimulation involves activation of mTOR downstream effectors.

Novel use of tryptose sulfite cycloserine egg yolk agar for isolation of Clostridium perfringens during an outbreak of necrotizing enterocolitis in a neonatal unit

Clostridium perfringens has been associated with necrotizing enterocolitis (NEC), which is a serious disease of neonates. Our study describes the novel use of selective tryptose sulfite cycloserine with egg yolk agar (TSC-EYA) during a nursery outbreak. This medium provides a rapid, sensitive, and accurate presumptive identification of C. perfringens.

The infant intestinal microbiome: friend or foe?

During the course of mammalian evolution there has been a close relationship between microbes residing in the gastrointestinal (GI) tract and the mammalian host. Interactions of resident intestinal microbes with the luminal contents and the mucosal surface play important roles in normal intestinal development' nutrition and adaptive innate immunity. The GI tract of the premature infant has a large but fragile surface area covered by a thin monolayer of epithelial cells that overlies a highly immunoreactive submucosa. Interactions in the lumen between microbes, nutrients and the intestinal mucosa can range from a healthy homeostasis to an uncontrolled systemic inflammatory response syndrome (SIRS) that leads to multiple organ system failure and death. Recent advances in molecular microbiota analytic methodology that stem from advances in high throughput sequencing technology have provided us with the tools to determine the GI microbiota in great depth, including the nearly 80% of microbes in the intestine that are very difficult if not impossible to culture by current methodology. Application of these techniques to derive a better understanding of the developing intestinal ecosystem in the premature neonate may hold the key to understand and eventually prevent several important diseases including necrotizing enterocolitis (NEC) and late onset neonatal sepsis that may be acquired via translocation through the GI tract.

Cluster of necrotizing enterocolitis in a neonatal intensive care unit: New Mexico, 2007

Background

Although the cause of necrotizing enterocolitis (NEC) is unknown, infection control practices have been shown to play an important role in containing many outbreaks. We investigated the etiology of a cluster of NEC in a level 3 neonatal intensive care unit and monitored for new cases following the implementation of enhanced infection control measures.

Methods

Investigators performed a chart and laboratory review for neonates with a diagnosis of NEC during January 1, 2007, to February 13, 2007, to identify risk factors. Enhanced environmental cleaning, cohorting of infants and nurses, and increased attention to hand hygiene were instituted. Commercial feeding products in the unit were tested for bacterial contamination. Close monitoring for new cases continued for 2 months following the identification of the cluster.

Results

Eleven cases of NEC were identified during the study period. Patients had a median of 5 disease risk factors (range, 3-8). Four distinct pathogens were detected in blood or stool specimens from 4 different patients. One sample of human milk fortifier (HMF) tested contained a colony count of Bacillus cereus at the US Food and Drug Administration's upper microbiologic limit for contamination. Seven (65%) patients received HMF before symptom onset, and 9 (82%) patients received 1 or more types of liquid formula. Only 1 new case was identified during the period of close monitoring.

Conclusion

A microbiologic cause was not identified, and, although the cluster might have resolved spontaneously, enhanced infection control and changing batches of HMF might have played a role in controlling this outbreak.

Role of LPS/CD14/TLR4-mediated inflammation in necrotizing enterocolitis: pathogenesis and therapeutic implications

AIM

To establish the roles of lipopolysaccharide (LPS)/CD14/toll-like receptor 4 (TLR4)-mediated inflammation in a rat model of human necrotizing enterocolitis (NEC).

METHODS

Six pairs of intestinal samples from human NEC were collected before and after recovery for histological and molecular analysis of inflammatory cytokines and signaling components. In the rat NEC model, we isolated 10-cm jejunum segments and divided them into six groups (n = 6) for sham operation, treatment with LPS, bowel distension, combined bowel distension and LPS stimulation, and two therapeutic groups. The potential efficacy of a recombinant CD18 peptide and a monoclonal CD14 antibody was evaluated in the latter two groups. The serum and tissue levels of several inflammatory mediators were quantified by real-time polymerase chain reaction, ELISA and immunoblotting.

RESULTS

Human acute phase NEC tissues displayed significant increases (P < 0.05) in levels of TLR4, CD14, myeloid differentiation protein (MD)-2, tumor necrosis factor (TNF)-alpha and nuclear factor-kappaB when compared to those after recovery. The histological and inflammatory picture of human NEC was reproduced in rats that were treated with combined bowel distension and LPS, but not in the sham-operated and other control rats. Serum levels of interleukin-6 and TNF-alpha were also elevated. The NEC pathology was attenuated by treating the NEC rats with a monoclonal CD14 antibody or an LPS-neutralizing peptide.

CONCLUSION

LPS and distension are required to produce the histological and inflammatory features of NEC. A potential treatment option is blocking LPS activation and leukocyte infiltration.

Antecedents of Bell stage III necrotizing enterocolitis

OBJECTIVE

New biopharmaceuticals hold promise for preventing or treating necrotizing enterocolitis. However, it is unclear whether any such biopharmaceutical that requires enteral administration could be administered using an 'early-treatment' paradigm. This study was undertaken to assess this issue based on data from every case of Bell stage III NEC cared for during the past 7 years at Intermountain Healthcare.

STUDY DESIGN

Patients with Bell stage III NEC were identified from electronic medical record repositories and the diagnosis was validated using operative reports. Electronic and paper records of each patient were then used to identify potential clinical and laboratory antecedents occurring within the 48 h period preceding the diagnosis of NEC.

RESULT

One hundred eighteen patients had Stage III NEC. The earliest recognized antecedents were nonspecific for NEC (apnea/bradycardia, skin mottling and irritability). These were recorded at 2.8+/-2.1, 4.5+/-3.1 and 5.4+/-3.7 (mean+/-s.d.) hours, respectively, before NEC was diagnosed. The most commonly identified gastrointestinal antecedents were blood in the stools, increased abdominal girth and elevated pre-feeding gastric residuals or emesis. These were identified 2.0+/-1.9, 2.8+/-3.1 and 4.9+/-4.0 h before NEC was recognized. Thirty-eight percent had a blood transfusion (18+/-12 h) preceding the NEC. Tachycardia, tachypnea, hypotension and diarrhea were rarely identified as antecedents and no consistent laboratory antecedents were discovered.

CONCLUSION

We judge that an 'early treatment of NEC' paradigm testing any pharmacological agent that must be administered enterally is not feasible. The first recognized antecedents of Bell stage III NEC are nonspecific for gastrointestinal pathology and insufficient time exists for dosing between the first gastrointestinal signs and placement of the gastric decompression tube.

Lactobacillus rhamnosus blocks inflammatory signaling in vivo via reactive oxygen species generation

Uncontrolled inflammatory responses in the immature gut may play a role in the pathogenesis of many intestinal inflammatory syndromes that present in newborns or children, such as necrotizing enterocolitis (NEC), idiopathic inflammatory bowel diseases (IBD), or infectious enteritis. Consistent with previous reports that murine intestinal function matures over the first 3 weeks of life, we show that inflammatory signaling in the neonatal mouse gut increases during postnatal maturation, with peak responses occurring at 2-3 weeks. Probiotic bacteria can block inflammatory responses in cultured epithelia by inducing the generation of reactive oxygen species (ROS), which inhibit NF-kappaB activation through oxidative inactivation of the key regulatory enzyme Ubc12. We now report for the first time that the probiotic Lactobacillus rhamnosus GG (LGG) can induce ROS generation in intestinal epithelia in vitro and in vivo. Intestines from immature mice gavage fed LGG exhibited increased GSH oxidation and cullin-1 deneddylation, reflecting local ROS generation and its resultant Ubc12 inactivation, respectively. Furthermore, prefeeding LGG prevented TNF-alpha-induced intestinal NF-kappaB activation. These studies indicate that LGG can reduce inflammatory signaling in immature intestines by inducing local ROS generation and may be a mechanism by which probiotic bacteria can prevent NEC in premature infants or reduce the severity of IBD in children.

Enteral glutamine and/or arginine supplementation have favorable effects on oxidative stress parameters in neonatal rat intestine

OBJECTIVE

To investigate and compare the effects of enteral glutamine and arginine supply on lipid peroxidation and antioxidant enzyme levels in the small intestine of healthy breast-fed rats.

MATERIALS AND METHODS

The study comprised 40 newborn Sprague-Dawley rats born to 5 mother rats. Newborn rats were randomly divided into 4 groups. Starting from day 1 until day 21, group I received only breast milk; group II received breast milk and 200 mg/kg/day oral glutamine; group III received breast milk and 200 mg/kg/day oral arginine; and group IV received breast milk, 200 mg/kg/day glutamine, and 200 mg/kg/day arginine. Malondialdehyde levels and glutathione peroxidase (GPx) and superoxide dismutase activities were measured.

RESULTS

The lowest malondialdehyde levels were found in group II (P = 0.0001). Superoxide dismutase activity was found to be significantly higher in group II than group I (P < 0.001). Of the 4 groups, GPx activity was highest in group IV. GPx activity in group II was significantly higher than in group I (P = 0.001) or group III (P = 0.001). GPx activity was higher in group IV than in group I (P = 0.001) or group III (P = 0.001).

CONCLUSIONS

Enteral glutamine alone or in the presence of arginine has favorable effects on oxidative stress not only in experimental models of hypoxia-reoxygenation, but also in healthy newborn rats. This suggests that in premature neonates with insufficient oxidative resistance, glutamine and arginine supplementation may help prevent necrotizing enterocolitis.

Biomarkers for infants at risk for necrotizing enterocolitis: clues to prevention?

Necrotizing enterocolitis (NEC) is the most common severe gastrointestinal emergency that affects premature newborns. This disease often has a rapid onset with few, if any, antecedent signs that can be used to reliably predict its occurrence. Its rapid onset and progression to death, as well as its severe morbidity when the infant survives, begs for early diagnostic tools that may be used in determining those infants who would be at greatest risk for development of the disease and for whom early preventative measures could be targeted. Although studies have suggested efficacy of several techniques such as breath hydrogen, inflammatory mediators in blood, urine or stool, and genetic markers, these all have drawbacks limiting their use. The application of newly developed "omic" approaches may provide biomarkers for early diagnosis and targeted prevention of this disease.

Necrotising enterocolitis in a term neonate with trisomy 21 exposed to maternal HIV and antiretroviral medication

Necrotising enterocolitis (NEC) was diagnosed in a term infant with Down's syndrome exposed to maternal human immunodeficiency virus (HIV) infection and antiretroviral therapy.