Neonatal necrotizing enterocolitis: diagnosis, management, and pathogenesis

Surgical Necrotizing Enterocolitis - Can We Predict the Need for Gastrostomy Tube Placement?

INTRODUCTION

Necrotizing enterocolitis (NEC) is a significant cause of morbidity and mortality among extremely premature infants. Approximately 50% of cases progress to surgery, frequently resulting in resection of necrotic bowel and ostomy creation. Premature neonates are at risk for bronchopulmonary dysplasia and feeding failure; surgery in these patients is higher risk. We evaluated the incidence of gastrostomy tube (GT) placement after ostomy reversal in surgical NEC to define a subset of patients who would benefit from concurrent ostomy reversal and GT placement.

METHODS

A single-center retrospective study of infants with surgical NEC requiring ostomy creation between 2007 and 2021 was performed.

RESULTS

Eighty patients met inclusion criteria. A GT was placed in 45/80 (56.3%), of which 3/45 (6.7%) were placed before, 20/45 (44.4%) concurrently with, and 22/45 (48.9%) after ostomy reversal. Between those who did and did not require GT placement, there were no significant differences in gestational age (27 versus 27 wk, P = 0.94) or birth weight (830 g versus 1055 g, P = 0.36). Hospital length of stay was longer in the GT group (128.2 versus 70.9 d, P < 0.0001). Time from ostomy reversal to hospital discharge was shorter when performed concurrently with GT (56 versus 77 d, P = 0.02). There were no differences in short-term or long-term GT related complications based on timing of GT placement.

CONCLUSIONS

GT placement occurred in approximately 50% of patients with surgical NEC and GT may be accomplished safely at the time of ostomy reversal thus reducing the need for an additional procedure.

Abnormal Splanchnic Regional Saturations in a Preterm Infant That Developed Necrotizing Enterocolitis Following a Red Blood Cell Transfusion

BACKGROUND

Necrotizing enterocolitis (NEC) has been associated with red blood cell (RBC) transfusions in preterm infants. Near-infrared spectroscopy (NIRS) can be used to noninvasively monitor regional oxygen saturations (rSO2).

CLINICAL FINDINGS

This former 28-week female premature infant, 29 days old, received an RBC transfusion due to increased apneic spells and a hematocrit of 27%. Within 24 hours she developed abdominal distension and passed a bloody stool (Bell's stage 2 NEC on abdominal x-ray). She completed 7 days of antibiotics and nothing-by-mouth status and was discharged home on room air and oral feedings on day of life 70.

PRIMARY DIAGNOSIS

We describe the presentation of NEC following a RBC transfusion in a preterm infant monitored with cerebral and splanchnic NIRS.

INTERVENTIONS

Mean rSO2 (cerebral and splanchnic) measurements were continuously recorded and calculated in 30-minute periods at baseline (prior to packed RBC transfusion), every hour during the RBC transfusion, and every 3 hours for the following 48 hours.

OUTCOMES

In this infant, average baseline splanchnic rSO2 was low at 46.5%, and increased during transfusion to 65%. However, following the RBC transfusion and an enteral feeding, splanchnic rSO2 dramatically decreased to 26%, and remained low until the time of NEC diagnosis.

PRACTICE RECOMMENDATIONS

To develop awareness of the increased risk for NEC in premature infants with significant anemia that receive packed RBC transfusions. With further studies and education, NIRS could be a valuable tool for the nurses and medical team to identify these at-risk neonates.

Interleukin 6 receptor alpha expression in PMNs isolated from prematurely born neonates: decreased expression is associated with differential mTOR signaling

BACKGROUND

Dysregulated inflammation leads to morbidity and mortality in neonates. Neutrophil-mediated inflammation can cause inflammatory tissue damage. The mammalian target of rapamycin (mTOR) pathway governs IL-6Rα protein expression in human neutrophils. Shed IL-6Rα then participates in trans-signaling of IL-6/IL-6Rα to cells not otherwise sensitive to IL-6. Signaling to endothelial cells triggers efferocytosis where macrophages limit persistent inflammation by phagocytizing neutrophils. We hypothesized that preterm neonatal PMNs fail to synthesize IL-6Rα due to alterations in mTOR signaling.

METHODS

We studied IL-6Rα expression, PAF receptor expression, and mTOR signaling in plasma and PAF-stimulated PMNs isolated from newborn infants and healthy adults using ELISA, real-time RT-PCR, western blotting, flow cytometry, and immunocytochemistry with phospho-specific antibodies.

RESULTS

Compared to healthy adults, plasma from neonates contains significantly less soluble IL-6Rα. IL-6Rα mRNA expression in PAF-stimulated PMNs does not differ between neonates and adults, but IL-6Rα protein expression is decreased in preterm neonatal PMNs. Rapamycin, an mTOR inhibitor, blocks IL-6Rα protein expression. mTOR signaling following PAF stimulation is decreased in preterm neonatal PMNs.

CONCLUSIONS

Preterm neonatal PMNs exhibit decreased mTOR pathway signaling leading to decreased IL-6Rα synthesis. Decreased synthesis of IL-6Rα by neonatal PMNs may result in decreased IL-6/IL-6Rα trans-signaling with prolonged inflammatory response and increased morbidity.

Correlation of serum KL-6 and CC16 levels with neurodevelopmental outcome in premature infants at 12 months corrected age

The aim of this study was to evaluate KL-6 and CC16 levels and their correlation with neurodevelopmental outcome among very low birth weight pre-term infants at 12 months corrected age. This prospective cohort study was performed from 2011 to 2013 by enrolling pre-term neonates of gestational age ≤ 32 weeks and birth weight ≤ 1500 g. Serum KL-6 and CC16 levels were determined 7 days after birth and their correlation with neurodevelopment was evaluated using Gesell Mental Developmental Scales. Of the 86 eligible pre-term infants, 63 completed follow-up, of which 15 had bronchopulmonary dysplasia. At 12 months corrected age, 49 infants had favorable outcomes and 14 infants had poor neurodevelopmental outcome. KL-6 levels were higher and CC16 levels were lower in infants with poor neurodevelopmental outcome compared with those infants who had favourable neurodevelopmental outcome. Serum KL-6 levels less than 90.0 ng/ml and CC16 levels greater than 320.0 pg/ml at 7 days of life were found to be predictive of a favourable outcome at 12 months corrected age. These biological markers could predict neurodevelopmental outcome at 12 months corrected age in very low birth weight premature infants, and help the clinician plan early therapeutic interventions to minimize or avoid poor neurodevelopmental outcome.

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.

Risk factors and outcome in neonatal necrotising enterocolitis

OBJECTIVES

To analyze multiple risk factors of necrotizing enterocolitis (NEC) and the outcome.

METHODS

Hundred neonates with NEC were compared with 100 normal neonates matched for sex, gestation and weight. Their data including antenatal, natal, course of illness, hospital stay, progress and outcome were collected. Univariate analysis and logistic regression were used to analyze the risk factors.

RESULTS

Mean age of onset of NEC was 2.35 ± 1.11 d. Stage I, II and III were noted in 48 %, 39 % and 13 % of cases respectively. Most common clinical features were abdominal distension (85 %) and feed intolerance (70 %). Important risk factors associated with NEC were sepsis, top feeding, perinatal asphyxia, respiratory distress and mechanical ventilation. Antenatal steroids and breast feeding had beneficial effect. No association was found with occurrence of NEC and cyanotic heart disease or administration of H2 blockers. Outcome in stage III was very poor.

CONCLUSIONS

Early identification of risk factors and appropriate intervention may reduce the incidence and improve the outcome in NEC.

Recruitment of dendritic cells is responsible for intestinal epithelial damage in the pathogenesis of necrotizing enterocolitis by Cronobacter sakazakii

Cronobacter sakazakii is a Gram-negative pathogen associated with the cases of necrotizing enterocolitis (NEC) that result from formula contamination. In a mouse model of NEC, we demonstrate that C. sakazakii infection results in epithelial damage by recruiting greater numbers of dendritic cells (DCs) than macrophages and neutrophils in the gut and suppresses DC maturation, which requires outer membrane protein A (OmpA) expression in C. sakazakii. Pretreatment of intestinal epithelial cell monolayers with supernatant from OmpA(+) C. sakazakii/DC culture markedly enhanced membrane permeability and enterocyte apoptosis, whereas OmpA(-) C. sakazakii/DC culture supernatant had no effect. Analysis of OmpA(+) C. sakazakii/DC coculture supernatant revealed significantly greater TGF-β production compared with the levels produced by OmpA(-) C. sakazakii infection. TGF-β levels were elevated in the intestinal tissue of mice infected with OmpA(+) C. sakazakii. Cocultures of CaCo-2 cells and DCs in a "double-layer" model followed by infection with OmpA(+) C. sakazakii significantly enhanced monolayer leakage by increasing TGF-β production. Elevated levels of inducible NO synthase (iNOS) were also observed in the double-layer infection model, and abrogation of iNOS expression prevented the C. sakazakii-induced CaCo-2 cell monolayer permeability despite the presence of DCs or OmpA(+) C. sakazakii/DC supernatant. Blocking TGF-β activity using a neutralizing Ab suppressed iNOS production and prevented apoptosis and monolayer leakage. Depletion of DCs in newborn mice protected against C. sakazakii-induced NEC, whereas adoptive transfer of DCs rendered the animals susceptible to infection. Therefore, C. sakazakii interaction with DCs in intestine enhances the destruction of the intestinal epithelium and the onset of NEC due to increased TGF-β production.

[Are mydriatic eyedrops dangerous for pre-term infants?]

The funduscopic examination is essential in neonatology to screen for retinopathy in the pre-term infant. Mydriatic eyedrops, which are used for this examination, are known to induce digestive side effects. We present a case of necrotizing enterocolitis developing in a pre-term infant as a complication of mydriatics. This infant was a girl born at 28 weeks gestation and 5 days, with Down's syndrome, who died on the 44th day of life, due to necrotizing enterocolitis, after instillation of 1 drop of atropine 0.3% in each eye. The chronology of events, the application method, and the clinical symptoms of atropine impregnation argue in favor of a causal relationship between atropine and necrotizing enterocolitis. The review of the literature made on the basis of this observation shows that side effects of mydriatic eyedrops are frequent in pre-term infants and raise the question of atropine hypersensitivity in pre-term infants with Down's syndrome.

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.

Nosocomial infection in small for gestational age newborns with birth weight <1500 g: a multicentre analysis

OBJECTIVE

To investigate whether preterm newborns who are small for gestational age are at increased risk of nosocomial infections and necrotising enterocolitis.

DESIGN, SETTING AND SUBJECTS

The German national surveillance system for nosocomial infection in very low birthweight infants uses the US Centers for Disease Control and Prevention criteria. 2918 newborns (24-28 weeks), born between 2000 and 2004, were selected after application of predefined inclusion criteria to ensure similar proportions of small and appropriate weight for gestational age newborns across gestational age groups.

MAIN OUTCOME MEASURES

The outcome criterion was at least one episode of nosocomial sepsis, pneumonia or necrotising enterocolitis. Adjusted odds ratios and corresponding 95% CIs were calculated based on general estimating equation models.

RESULTS

The study population consisted of 13% (n = 392) small and 87% (n = 2526) appropriate weight for gestational age infants. 33% (n = 950) of the infants experienced at least one episode of sepsis: 42% (n = 163) of small and 31% (n = 787) of appropriate weight for gestational age newborns (adjusted OR 1.41, 95% CI 1.05 to 1.89). Pneumonia was diagnosed in 6% (n = 171) of infants: 8.4% (n = 33) of small and 5.5% (n = 138) of appropriate weight for gestational age newborns (adjusted OR 1.57, 95% CI 1.19 to 5.57). Necrotising enterocolitis was documented in 5.2% (n = 152) of infants: 7.1% (n = 28) of small and 4.9% of (n = 124) appropriate weight for gestational age newborns (adjusted OR 1.20, 95% confidence interval 0.75 to 1.94).

CONCLUSIONS

Growth-retarded preterm infants seem to be at increased risk of nosocomial infection, irrespective of the responsible pathogen. Future immunological research should elucidate potential causal associations.

Low levels of procalcitonin during episodes of necrotizing enterocolitis

The pathogenesis of necrotizing enterocolitis (NEC) remains poorly understood. We aimed to assess the extent of bacterial infection in the pathogenesis of NEC using serial procalcitonin measurements. Blood samples were drawn during the first 4 days following every clinical event requiring a workup for presumed NEC. Eight episodes were confirmed as NEC, 7 of which showed procalcitonin levels <1 ng/ml at presentation and <1.3 ng/ml thereafter, comparable to 24 healthy controls. The one infant with elevated procalcitonin had bacteremia in addition to NEC. Procalcitonin levels of 24 matched septic infants were higher than those of NEC infants, peaking at 4.1 ng/ml. We conclude that low procalcitonin values are the rule during episodes of NEC and provide further evidence that overactive local immune response, and not active infection, is primarily responsible for the mucosal damage in NEC.

Role of neuronal nitric oxide synthase and inducible nitric oxide synthase in intestinal injury in neonatal rats

AIM: To investigate the dynamic change and role of neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS) in neonatal rat with intestinal injury and to define whether necrotizing enterocolitis (NEC) is associated with the levels of nitric oxide synthase (NOS) in the mucosa of the affected intestine tissue.

METHODS: Wistar rats less than 24 h in age received an intraperitoneal injection with 5 mg/kg lipopolysaccharide (LPS). Ileum tissues were collected at 1, 3, 6, 12 and 24 h following LPS challenge for histological evaluation of NEC and for measurements of nNOS and iNOS. The correlation between the degree of intestinal injury and levels of NOS was determined.

RESULTS: The LPS-injected pups showed a significant increase in injury scores versus the control. The expression of nNOS protein and mRNA was diminished after LPS injection. There was a negative significant correlation between the nNOS protein and the grade of median intestinal injury within 24 h. The expression of iNOS protein and mRNA was significantly increased in the peak of intestinal injury.

CONCLUSION: nNOS and iNOS play different roles in LPS-induced intestinal injury. Caution should be exerted concerning potential therapeutic uses of NOS inhibitors in NEC.