Prevention of necrotising enterocolitis: Year 2004 and beyond

Early Antibiotic Exposure Alters Intestinal Development and Increases Susceptibility to Necrotizing Enterocolitis: A Mechanistic Study

Increasing evidence suggests that prolonged antibiotic therapy in preterm infants is associated with increased mortality and morbidities, such as necrotizing enterocolitis (NEC), a devastating gastrointestinal pathology characterized by intestinal inflammation and necrosis. While a clinical correlation exists between antibiotic use and the development of NEC, the potential causality of antibiotics in NEC development has not yet been demonstrated. Here, we tested the effects of systemic standard-of-care antibiotic therapy for ten days on intestinal development in neonatal mice. Systemic antibiotic treatment impaired the intestinal development by reducing intestinal cell proliferation, villi height, crypt depth, and goblet and Paneth cell numbers. Oral bacterial challenge in pups who received antibiotics resulted in NEC-like intestinal injury in more than half the pups, likely due to a reduction in mucous-producing cells affecting microbial-epithelial interactions. These data support a novel mechanism that could explain why preterm infants exposed to prolonged antibiotics after birth have a higher incidence of NEC and other gastrointestinal disorders.

Histological analysis of the intestinal wall of newborn rats submitted to hypoxia and reoxygenation to evaluate the protective effect of N-Acetylcysteine

Purpose

To evaluate the effect of N-Acetylcysteine (NAC) in newborn rats submitted to hypoxia and reoxygenation (H/R) conditions in an experimental model of necrotizing enterocolitis.

Methods

Eight pregnant rats and their 70 cubs were used (5 groups) and exposed to H/R conditions and received NAC at different times. The animals in the H/R groups were placed in a gas chamber (100% CO²) for 10 minutes and then reoxygenated for 10 minutes (100% O²), twice a day for the first three days of life, with a six-hour span between events. On the third day of life, the animals were anesthetized, laparotomized and the intestines were resected.

Results

The H/R and NAC groups showed changes in the intestinal wall in relation to the number, height and width of the villi when compared to the control group (p<0.0001), but with better preservation of structures in the NAC group. There were no differences between groups regarding the number (%) of mitoses.

Conclusion

The administration of NAC decreased the lesions in the intestinal wall of rats submitted to H/R, therefore suggesting that this drug can be used to prevent the development of necrotizing enterocolitis in newborns.

Expert consensus to weight an adherence score for audit and feedback of practices that prevent necrotizing enterocolitis in very low birth weight infants

OBJECTIVE

Necrotizing enterocolitis (NEC) is a catastrophic abdominal complication threatening the life of premature infants, but adoption of prevention and early recognition practices differs as do NEC rates in Neonatal Intensive Care Units (NICUs). The purpose of this research was to validate and weight an evidence-based adherence score (aka NEC-Zero Adherence Score) to prevent and foster timely recognition of NEC.

STUDY DESIGN

An electronic Delphi (e-Delphi) approach was used to identify consensus. NEC experts were recruited via the NEC Society and surveyed until consensus and stability criteria for the Delphi were met (≥70% consensus and mean responses changed <15% between rounds).

RESULTS

Expert panelists (n=22) were experienced (M=17.6, SD 11years) and predominately physicians (68%) or neonatal nurse practitioners (18%). Consensus (>70% by item) supported a 10 point score. Points were distributed across 1) an exclusive human milk diet (5 points), 2) standardized feeding protocols (3 points), 3) antibiotic stewardship (1 point), and 4) a unit-specified approach to early recognition (1 point). Withholding feeding during transfusion was controversial (M=0.50, SD 0.73) and met consensus criteria to drop from the score.

CONCLUSIONS

Holding feeding during transfusion was dropped from the score. Relationships between the score and unit NEC rates as well as its utility for use in audit and feedback should be studied in the future.

Does rapid enteral feeding increase intestinal morbidity in very low birth weight infants? A retrospective analysis

PURPOSE

To investigate the association of a standardized rapid enteral feeding strategy (established in 2011 in our unit) with intestinal morbidity in very low birth weight (VLBW) infants.

METHODS

A total of 301 inborn VLBW infants were included in this single-centre retrospective cohort study. We compared the incidence of intestinal morbidity (defined as necrotizing enterocolitis or intestinal perforation) in slowly enterally fed infants in 2008-2010 (10 ml/kg/day increase of milk feeds) to a corresponding cohort of rapidly enterally fed infants in 2011-2013 (20 ml/kg/day increase of milk feeds). Univariate and multivariable logistic and linear regression analyses, respectively, were performed to control for confounding variables.

RESULTS

Both groups were similar regarding baseline demographic and perinatal characteristics. In univariate modeling, intestinal morbidity did not significantly differ between the two groups (p = 0.25), neither did all-cause mortality nor incidence of late onset sepsis in multivariable modeling. In contrast, length of hospital stay (HS) and duration of parenteral nutrition (PEN) were significantly shorter in the rapid group (HS: -8.35 days, p = 0.012 and PEN: -7.13 days, p < 0.001).

CONCLUSIONS

Implementation of a more rapid enteral feeding regime is safe in VLBW infants and may significantly shorten length of HS and PEN in this cohort.

Prevention of necrotizing enterocolitis in preterm very low birth weight infants: is it feasible?

Necrotizing enterocolitis (NEC) is still one of the most catastrophic intestinal emergencies in preterm very low-birth weight infants. Primary prevention of NEC should be the priority, since NEC frequently progresses from nonspecific signs, to extensive necrosis within a matter of hours with medical or surgical treatment, making successful treatment and secondary prevention difficult to achieve. Currently available strategies for primary prevention of NEC include antenatal glucocorticosteroids, breast milk feeding, cautious feeding strategy, fluid restriction and probiotics. Nonetheless, based on current research evidence, mixed flora probiotics, and/or breast milk feeding, would appear to be the most effective feasible methods in the prevention of NEC at present.

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.

Necrotizing enterocolitis: A multifactorial disease with no cure

Necrotizing enterocolitis is an inflammatory bowel disease of neonates with significant morbidity and mortality in preterm infants. Due to the multifactorial nature of the disease and limitations in disease models, early diagnosis remains challenging and the pathogenesis elusive. Although preterm birth, hypoxic-ischemic events, formula feeding, and abnormal bacteria colonization are established risk factors, the role of genetics and vasoactive/inflammatory mediators is unclear. Consequently, treatments do not target the specific underlying disease processes and are symptomatic and surgically invasive. Breast-feeding is the most effective preventative measure. Recent advances in the prevention of necrotizing enterocolitis have focused on bioactive nutrients and trophic factors in human milk. Development of new disease models including the aspect of prematurity that consistently predisposes neonates to the disease with multiple risk factors will improve our understanding of the pathogenesis and lead to discovery of innovative therapeutics.

Probiotics and other preventative strategies for necrotising enterocolitis

Necrotising enterocolitis (NEC) remains one of the commonest causes of death and significant morbidity in preterm infants after the first few postnatal days. NEC affects approximately 5-10% of infants born at <or=28 weeks; about a third will die. Although there do not appear to be any 'simple fixes', it is clear that there are many clinical strategies that affect NEC. There is controlled trial evidence for breast milk, fluid regimes, enteral antibiotics, immunonutrients and probiotic supplements. This paper will review the evidence relevant to current populations of preterm infants and determine which, if any, can be safely and effectively introduced into current clinical practice.

Prevention and treatment of necrotising enterocolitis in preterm neonates

Prevention and treatment of NEC has become an area of priority for research due to the increasing number of preterm survivors at risk, and the significant mortality and morbidity related to the illness. Probiotic supplementation appears to be a promising option for primary prevention of NEC but further large trials are necessary for documenting their safety in terms of sepsis as well as long-term neurodevelopmental outcomes and immune function. As new frontiers including immunomodulating agents like pentoxifylline continue to be explored, the impact of well-established simple strategies like antenatal glucocorticoid therapy, and early and preferential use of breast milk must not be forgotten. Clinical research on manifestations of ileus of prematurity, and feeding in the presence of common risk factors such as IUGR is needed. Safety of minimal enteral feeds in terms of NEC and benefits of standardised feeding regimens need to be confirmed. Association of common clinical practices such as red cell transfusions, H2 receptor blockade, and thickening of feeds with NEC warrants attention. An approach utilising a package of potentially better practices seems to be the most appropriate strategy for the prevention and treatment of NEC.

The Alabama Preterm Birth study: polymorphonuclear and mononuclear cell placental infiltrations, other markers of inflammation, and outcomes in 23- to 32-week preterm newborn infants

OBJECTIVE

The purpose of this study was to better understand the relationship between placental polymorphonuclear and mononuclear cell infiltrations with bacterial cultures, markers of inflammation, and preterm outcomes.

STUDY DESIGN

This was a prospective study in 446 women who were delivered of a singleton infant at <32 weeks of gestational age. Five placental sites were categorized as having polymorphonuclear or mononuclear infiltrations. Results were compared with placental and cord cultures, umbilical cord interleukin-6 levels, and neonatal outcomes.

RESULTS

Polymorphonuclear, but not mononuclear, cell infiltrations were more common at the earliest gestational ages and in black women (56.0% vs 39.3%; P < .01). Polymorphonuclear infiltration was associated with spontaneous preterm birth (73.9% vs 8.0%; P < .0001), but not with preeclampsia (9.9% vs 34%; P < .0001). Women with positive cultures, high interleukin-6 levels, and clinical chorioamnionitis all had significantly more polymorphonuclear infiltrations than did women without those conditions (all probability values, <.0001). In all sites, polymorphonuclear infiltration was associated with neonatal systemic inflammatory response syndrome (P < .0001) and in the cord with necrotizing enterocolitis (22.4% vs 13.5%; P = .02). Intraventricular hemorrhage and neonatal death were not associated with polymorphonuclear infiltration. Polymorphonuclear infiltration at all sites was associated with less respiratory distress syndrome (P < .01). Mononuclear cell infiltration, when present in the decidua basalis, was associated with an increase in neonatal intraventricular hemorrhage (23.8% vs 7.4%; P < .0004). Plasmacytic infiltrates were associated with increased intraventricular hemorrhage (29.4% vs 8.3%; P = .01) and neonatal death (27.8% vs 9.2%; P = .02).

CONCLUSION

Polymorphonuclear infiltrations of the free membranes, chorionic plate, and umbilical cord were associated with positive intrauterine cultures and elevated cord blood interleukin-6. There was also an association with systemic inflammatory response syndrome and necrotizing enterocolitis, but not with intraventricular hemorrhage or death, and with decreased respiratory distress syndrome. Decidual mononuclear cell infiltration was associated with an increased risk of intraventricular hemorrhage and decidual plasma cell infiltration with increased intraventricular hemorrhage and neonatal death.

Short bowel syndrome and intestinal transplantation in children

PURPOSE OF REVIEW

This review summarizes recent knowledge and clinical practice for pediatric patients suffering extensive intestinal resection causing short bowel syndrome. This condition requires the use of parenteral nutrition, as long as intestinal failure persists, and may be, in some selected cases, an indication for intestinal transplantation.

RECENT FINDINGS

Biological evaluation of intestinal failure is becoming possible with the use of plasma citrulline as a marker of intestinal mass. Few epidemiological data are available; some indicate an increased incidence of short bowel syndrome-related gastroschisis and persistent high incidence of necrotizing enterocolitis. Morbidity and mortality data in pediatric patients with short bowel syndrome are limited, while long-term outcome is better documented from recently reported cohorts. Non-transplant surgery is one of the best options for patients with unadapted short bowel syndrome. Isolated liver transplantation may be avoided. The use of trophic factors for enhancing mucosal hyperplasia still remains disappointing.

SUMMARY

The management should include therapies adapted to each stage of intestinal failure, based on a multidisciplinary approach in centers involving pediatric surgery, pediatric gastroenterology, parenteral nutrition expertise, home-parenteral nutrition program, and liver-intestinal transplantation experience. If managed appropriately, the prognosis of short bowel syndrome is excellent, with limited indications for intestinal and/or liver transplantation. Timing for patient referral in specialized centers remains an issue.

NICU update: state of the science of NEC

Necrotizing enterocolitis (NEC) is a disease process that is frequently seen in the neonatal intensive care unit (NICU) and in preterm newborns. The pathophysiology of NEC is a detailed multifactorial theory that will not be thoroughly discussed in this article. The key risk factors leading to NEC are prematurity, formula feeding, intestinal ischemia, and bacterial colonization. Current research regarding feeding practices, surgical techniques, bowel transplantation, and use of probiotics is presented to update NICU nurses on the state of the science of care for the newborn with NEC. Caring for the sick neonate involves holistic family care. Listening to and supporting parents through the stressful stay in the NICU can empower them to be better prepared and educated to take their newborns home.

State of the science: neonatal bacterial infection in the early 21st century

Bacterial infections continue to cause significant neonatal morbidity and mortality, especially in small preterm neonates in the neonatal intensive care unit. Maternal and newborn risk factors can be used to prevent newborn infection and initiate early clinical assessments, laboratory diagnostic tests, and antimicrobial agent therapies. Early-onset and late-onset infections have different clinical patterns; however, each must be recognized as soon as possible in order to optimize outcomes. Antibiotics have long been the mainstay of treatment but organism resistance and weak immune system functioning of very premature newborns makes treatment challenging. Research continues on other markers for infection that may lead to more rapid diagnosis. The discovery of new therapies to improve newborn immune system function promises further improvement in outcomes of newborn infection. This article gives an overview of the state of diagnosis and treatment of newborn infection.