Intestinal microbiota and blue baby syndrome: probiotic therapy for term neonates with cyanotic congenital heart disease

Particular genomic and virulence traits associated with preterm infant-derived toxigenic Clostridium perfringens strains

Clostridium perfringens is an anaerobic toxin-producing bacterium associated with intestinal diseases, particularly in neonatal humans and animals. Infant gut microbiome studies have recently indicated a link between C. perfringens and the preterm infant disease necrotizing enterocolitis (NEC), with specific NEC cases associated with overabundant C. perfringens termed C. perfringens-associated NEC (CPA-NEC). In the present study, we carried out whole-genome sequencing of 272 C. perfringens isolates from 70 infants across 5 hospitals in the United Kingdom. In this retrospective analysis, we performed in-depth genomic analyses (virulence profiling, strain tracking and plasmid analysis) and experimentally characterized pathogenic traits of 31 strains, including 4 from CPA-NEC patients. We found that the gene encoding toxin perfringolysin O, pfoA, was largely deficient in a human-derived hypovirulent lineage, as well as certain colonization factors, in contrast to typical pfoA-encoding virulent lineages. We determined that infant-associated pfoA+ strains caused significantly more cellular damage than pfoA- strains in vitro, and further confirmed this virulence trait in vivo using an oral-challenge C57BL/6 murine model. These findings suggest both the importance of pfoA+ C. perfringens as a gut pathogen in preterm infants and areas for further investigation, including potential intervention and therapeutic strategies.

Intestinal microbiome changes in an infant with right atrial isomerism and recurrent necrotizing enterocolitis: A case report and review of literature

BACKGROUND

Necrotizing enterocolitis (NEC) is a multifactorial disease that predominantly affects premature neonates. Intestinal dysbiosis plays a critical role in NEC pathogenesis in premature neonates. The main risk factor for NEC in term infants is mesenteric hypoperfusion associated with ductal-dependent congenital heart disease (CHD) that eventually leads to intestinal ischemia. The incidence of NEC in neonates with critical CHD is 6.8%-13%. However, the role of the intestinal microbiome in NEC pathogenesis in infants with ductal-dependent CHD remains unclear.

CASE SUMMARY

A male term neonate with right atrial isomerism underwent modified Blalock-Taussig shunt placement on the 14^th day of life and had persistent mesenteric hypoperfusion after surgery. The patient had episodes of NEC stage IIA on the 1^st and 28^th days after cardiac surgery. Fecal microbial composition was analyzed before and after cardiac surgery by sequencing region V4 of the 16S rRNA gene. Before surgery, species belonging to genera Veillonella and Clostridia and class Gammaproteobacteria were detected, Bifidobacteriaceae showed a low abundance. The first NEC episode was associated with postoperative hemodynamic instability, intestinal ischemia-reperfusion injury during cardiopulmonary bypass, and a high abundance of Clostridium paraputrificum (Clostridium sensu stricto I) (56.1%). Antibacterial therapy after the first NEC episode resulted in increased abundance of Gammaproteobacteria, decreased abundance of Firmicutes, and low alpha diversity. These changes in the microbial composition promoted the growth of Clostridium sensu stricto I (72.0%) before the second NEC episode.

CONCLUSION

A high abundance of Clostridium sensu stricto I and mesenteric hypoperfusion may have contributed to NEC in the present case.

Analyzing the Complicated Connection Between Intestinal Microbiota and Cardiovascular Diseases

Relentless human curiosity to understand the basis of every aspect of medical science has led humanity to unlock the deepest secrets about the physiology of human existence and, in the process, has reached milestones that a century ago could only be imagined. Recent ground-breaking breakthroughs have helped scientists and physicians all over the world to update the scientific basis of diseases and hence further improve treatment outcomes. According to recent studies, scientists have found a link between intestinal flora and the pathogenesis of diseases, including cardiovascular diseases. Any change in the typical habitat of gut microbiota has been shown to result in the culmination of various metabolic and cardiac diseases. Therefore, gut microbiota can be credited for influencing the course of the development of a disease. Any change in the composition and function of bacterial species living in the gut can result in both beneficial and harmful effects on the body. Gut microbiota achieves this role by numerous mechanisms. Generations of various metabolites like TMAO (trimethylamine N-oxide), increased receptibility of various bacterial antigens, and disruption of the enzyme action in various metabolic pathways like the bile acids pathway may result in the development of metabolic as well as cardiovascular diseases. Even if they may not be the only etiological factor in the pathogenesis of a disease, they may very well serve as a contributing factor in worsening the outcome of the condition. Studies have shown that they actively play a role in the progression of cardiovascular diseases like atherosclerotic plaque formation and rising blood pressure. The focus of this review article is to establish a relation between various cardiovascular diseases and gut microbiota. This could prove beneficial for clinicians, health care providers, and scientists to develop novel therapeutic algorithms while treating cardiac patients.

Disorders of gut microbiota in children with Tetralogy of Fallot

BACKGROUND

Gut microbiota plays an important role in cardiovascular health and disease, including congenital heart disease (CHD). Tetralogy of Fallot (TOF) is the most common form of cyanotic CHD characterized by systemic chronic hypoxia and sustained pressure overload of the right ventricle. It is well-known that hypoxia and pressure overload can affect gut microbiota. However, the effects of TOF on the gut microbiota remain little understood. This study explored the profile of the gut microbiota in children with unrepaired TOF.

METHODS

A total of 12 pediatric patients diagnosed with TOF and 9 healthy age- and gender-matched children were enrolled in this study. Fecal samples were collected from every participant and subjected to 16S rDNA gene sequencing. The raw sequencing data were processed using the Quantitative Insights Into Microbial Ecology pipeline.

RESULTS

A comparison of the gut microbiota revealed that pediatric patients with TOF had developed dysbiosis as reflected by the altered taxonomic composition and impaired functional profile. A total of 14 indicative bacterial genera were identified as differential biomarkers capable of distinguishing between healthy children and TOF patients. Furthermore, functional annotations revealed that the gut microbiota in TOF patients was characterized by increased levels of inflammatory, oxidative, and immune responses, and decreased activities of adaptation, synthesis, and metabolism.

CONCLUSIONS

Pediatric patients with unrepaired TOF have intestinal dysbacteriosis that is characterized by altered taxonomic composition and impaired functional profile. These findings suggested that the interplay between gut microbiota and the host may be dysregulated in patients with TOF.

Dysbiosis and Intestinal Barrier Dysfunction in Pediatric Congenital Heart Disease Is Exacerbated Following Cardiopulmonary Bypass

There are no data evaluating the microbiome in congenital heart disease following cardiopulmonary bypass. The authors evaluated patients with congenital heart disease undergoing cardiopulmonary bypass and noncardiac patients undergoing surgery without bypass. Patients with congenital heart disease had differences in baseline microbiome compared with control subjects, and this was exacerbated following surgery with bypass. Markers of barrier dysfunction were similar for both groups at baseline, and surgery with bypass induced significant intestinal barrier dysfunction compared with control subjects. This study offers novel evidence of alterations of the microbiome in congenital heart disease and exacerbation along with intestinal barrier dysfunction following cardiopulmonary bypass.

Necrotizing Enterocolitis in Children with Congenital Heart Disease: A Literature Review

Infants with congenital heart disease (CHD) are at an increased risk of developing necrotising enterocolitis (NEC), a serious inflammatory intestinal condition classically associated with prematurity. CHD not only increases the risk of NEC in preterm infants but is one of the most commonly implicated risk factors in term infants. Existing knowledge on the topic is limited largely to retrospective studies. This review acts to consolidate existing knowledge on the topic in terms of disease incidence, pathophysiology, risk factors, outcomes and the complex relationship between NEC and enteral feeds. Potential preventative strategies, novel biomarkers for NEC in this population, and the role of the intestinal microbiome are all explored. Numerous challenges exist in the study of this complex multifactorial disease which arise from the heterogeneity of the affected population and its relative scarcity. Nevertheless, its high related morbidity and mortality warrant renewed interest in identifying those infants most at risk and implementing strategies to reduce the incidence of NEC in infants with CHD.

Nutrition of neonates with congenital heart disease: existing evidence, conflicts and concerns

Introduction: Congenital heart disease is one of the most of the groups of congenital anomalies with an incidence of about 1 per 100 live births. Almost one-third of these infants require some type of intervention, usually in the first year of life and increasingly often in the neonatal period. Innovative reparative and palliative surgical procedures and advanced medical support in the Neonatal Intensive Care Unit have significantly reduced the mortality related to congenital heart disease. Achieving survival is not the only target of clinicians for these patients. Appropriate growth, development, and improved quality of life are also very important. Growth failure is a very common problem of these children and nutritional support and management are a challenge for health care providers. Early intervention and identification of at-risk patients have the potential to decrease morbidity and mortality related to malnutrition.Aim/methods: The purpose of this article is to analyze the existing evidence and common concerns about perioperative and postdischarge nutritional management of neonates with congenital heart disease based on the special issues or complications that may arise. Furthermore, we reviewed the recent literature about current practices and proposed policies that could prevent malnutrition and improve the outcomes of neonates with congenital heart disease.Results/conclusion: A standardized institutional protocol and clear guidelines referring to feeding initiation, prompt estimation of caloric needs and provision of adequate and appropriate nutrient intake is likely to benefit these patients. Clear definitions for the nutritional approach in the setting of medical complications and close assessment of growth by pediatricians and specialized nutritionists are crucial for the long-term outlook and quality of life of these infants.

Effect of a Dual-Strain Probiotic on Necrotizing Enterocolitis in Neonates with Ductal-Dependent Congenital Heart Disease: A Retrospective Cohort Study

BACKGROUND

Newborns with ductal-dependent congenital heart disease (CHD) are at increased risk for developing necrotizing enterocolitis (NEC).

OBJECTIVES

To investigate whether the use of dual-strain probiotics is beneficial for prevention of NEC in CHD patients, as demonstrated for premature infants.

STUDY DESIGN

Single-center retrospective cohort study of newborns with ductal-dependent CHD before and after implementation of oral dual-strain probiotics containing Bifidobacterium infantis and Lactobacillus acidophilus, on each day of exposure to prostaglandin E1 (PGE1).

RESULTS

Birth weight, gestational age, and distribution of heart defects were similar in both cohorts. NEC occurred in 6 of 247 (2.4%) patients without probiotics, and in 3 of 242 (1.2%) patients who received probiotics (p = 0.504). NEC-related mortality (0.4 vs. 0.4%, p = 1.000) and overall mortality (11.0 vs. 8.7%, p = 0.448) were likewise not different. PGE1 exposure was 1,788 and 2,455 days, respectively. In subgroup analysis of 152 infants with aortic arch malformations, such as coarctation of the aorta and interrupted aortic arch, we observed a significant reduction of NEC frequency (5.6 vs. 0.0%, p = 0.048).

CONCLUSIONS

This is the first study to investigate the effect of a dual-strain probiotic on NEC in CHD patients. Infants with aortic arch malformations appear to benefit from dual-strain probiotics. Due to the scarcity of concurrence of ductal-dependent CHD and NEC, a clinical trial on probiotics to decrease risk of NEC in infants with ductal-dependent CHD would require several thousand infants.

Human Milk Use in the Preoperative Period Is Associated with a Lower Risk for Necrotizing Enterocolitis in Neonates with Complex Congenital Heart Disease

OBJECTIVE

To evaluate the hypothesis that feeding volumes exceeding 100 mL/kg/d and exposure to cow's milk formula preoperatively increase the risk for preoperative necrotizing enterocolitis (NEC) in infants with complex congenital heart disease.

STUDY DESIGN

All infants, of any gestational age, with an isolated cardiac lesion at high risk for NEC (ductal-dependent lesions, transposition of the great arteries, truncus arteriosus, and aorto-pulmonary window) admitted to Texas Children's Hospital from 2010 to 2016 were included. NEC was defined based on the modified Bell criteria. Feeding regimen information and relevant covariates were collected. Logistic regression was used to evaluate the association of feeding regimen and other potential risk factors with NEC.

RESULTS

In this single-center, retrospective cohort of 546 infants, 3.3% developed Bell stage I-III NEC preoperatively. An exclusive unfortified human milk diet was associated with a significantly lower risk of preoperative NEC (OR 0.17, 95% CI 0.04-0.84, P = .03) in a multivariable regression model controlling for cardiac lesion, race, feeding volume, birth weight small for gestational age, inotrope use presurgery/pre-NEC, and prematurity. Feeding volumes exceeding 100 mL/kg/d were associated with a significantly greater risk of preoperative NEC (OR 3.05, 95% CI 1.19-7.90, P = .02).

CONCLUSIONS

The findings suggest that an unfortified exclusive human milk diet may reduce the risk of preoperative NEC in infants with complex congenital heart disease.

Preoperative Feeds in Ductal-Dependent Cardiac Disease: A Systematic Review and Meta-analysis

CONTEXT

Our aim for this review is to determine if preoperative feeds in neonates with ductal-dependent congenital heart disease are harmful or beneficial.

OBJECTIVES

To summarize current evidence for preoperative feeding in neonates with ductal-dependent congenital heart disease.

DATA SOURCES

We used the following databases: Medline, Embase, and Cochrane Central Register of Controlled Trials.

STUDY SELECTION

We included observational studies in which the following outcomes were addressed: necrotizing enterocolitis (NEC), hospital length of stay (LOS), time to achieve full postoperative enteral feeding, and feeding intolerance.

DATA EXTRACTION

Two reviewers independently screened each study for eligibility and extracted data. Methodologic quality was assessed by using a standardized item bank, and certainty of evidence for each outcome was assessed by using Grading of Recommendations Assessment, Development and Evaluation criteria.

RESULTS

Five retrospective cohort studies were eligible for inclusion, for which risk of bias was significant. When comparing neonates who received preoperative feeds with those who did not, there was no significant difference in NEC (pooled odds ratio = 1.09 [95% confidence interval 0.06-21.00; P = .95]; 3 studies, 6807 participants, very low certainty evidence), hospital LOS (mean of 14 days for those not fed versus 9.9 days for those fed preoperatively; P < .01; 1 study, 57 participants, very low certainty evidence), or feeding intolerance (odds ratio = 2.014 [95% confidence interval 0.079-51.703; P = .67]; 1 study, 56 participants, very low certainty evidence). No data were available for the outcome time to achieve full postoperative enteral feeding. All studies were observational and had small sample sizes.

CONCLUSIONS

There is insufficient evidence to suggest that preoperative enteral feeds in patients with ductal-dependent cardiac lesions adversely influence the rate of NEC, LOS, or feeding intolerance.

Hypoxia induces senescence of bone marrow mesenchymal stem cells via altered gut microbiota

Systemic chronic hypoxia is a feature of many diseases and may influence the communication between bone marrow (BM) and gut microbiota. Here we analyse patients with cyanotic congenital heart disease (CCHD) who are experiencing chronic hypoxia and characterize the association between bone marrow mesenchymal stem cells (BMSCs) and gut microbiome under systemic hypoxia. We observe premature senescence of BMSCs and abnormal d-galactose accumulation in patients with CCHD. The hypoxia that these patients experience results in an altered diversity of gut microbial communities, with a remarkable decrease in the number of Lactobacilli and a noticeable reduction in the amount of enzyme-degraded d-galactose. Replenishing chronic hypoxic rats with Lactobacillus reduced the accumulation of d-galactose and restored the deficient BMSCs. Together, our findings show that chronic hypoxia predisposes BMSCs to premature senescence, which may be due to gut dysbiosis and thus induced d-galactose accumulation.

Systemic chronic hypoxia is a feature of many diseases and may influence the communication between bone marrow and gut microbiota. Here, the authors show that chronic hypoxia predisposes bone marrow stem cells to premature senescence, which may be due to gut dysbiosis and gut microbiota-derived d-galactose accumulation.

Nutrition in the Cardiac Newborns: Evidence-based Nutrition Guidelines for Cardiac Newborns

Both protein and energy malnutrition are common in neonates and infants with congenital heart disease (CHD). Neonates with CHD are at increased risk of developing necrotizing enterocolitis (NEC), particularly the preterm population. Mortality in patients with CHD and NEC is higher than for either disease process alone. Standardized feeding protocols may affect both incidence of NEC and growth failure in infants with CHD. The roles of human milk and probiotics have not yet been explored in this patient population.

A pilot study of Bifidobacterium breve in neonates undergoing surgery for congenital heart disease

Background

Probiotics have currently been widely used in patients undergoing various types of surgeries and improved their clinical outcomes, while data in pediatric cardiac surgery have been lacking. We investigated the safety and effects on the intestinal microbiota of the probiotic Bifidobacterium breve in neonates undergoing surgery for congenital heart disease.

Methods

This pilot, randomized study was performed in a single-center, university hospital-based pediatric intensive care unit (PICU). Twenty-one neonates undergoing surgery for congenital heart disease at >7 days after birth were randomly allocated to two groups: group A received 3 × 10⁹ colony-forming units (CFU)/day of enteral B. breve strain Yakult (BBG-01), which was started 1 week before and terminated 1 week after surgery (n = 10), and group B did not receive BBG-01 (n = 11).

Results

The characteristics of the patients were similar in both groups. The postoperative days until fulfillment of the criteria for discharge from the PICU tended to be fewer in group A (8 [7–8] days) than in group B (9 [8–14] days) (p = 0.10). Likewise, the postoperative days to enteral nutrition or achievement of caloric goal tended to be fewer in group A than in group B. The Bifidobacterium in fecal samples after initiating BBG-01 in group A were significantly higher in number than that in group B. Enterobacteriaceae were significantly fewer in group A than in group B immediately (7.0 [3.9–7.7] vs. 8.5 [8.0–9.1] log₁₀ cells/g) and 1 week (7.7 [7.0–8.1] vs. 9.3 [8.6–9.5] log₁₀ cells/g) after surgery (p < 0.05 for both comparisons). The number of Pseudomonas after 1 week was significantly lower in group A than in group B (p = 0.04). The concentrations of total organic and acetic acids were also significantly higher in group A than in group B. The postoperative course was uncomplicated and all neonates were discharged alive from the PICU.

Conclusions

The perioperative administration of a probiotic to neonates undergoing surgery for congenital heart disease was safe and significantly improved their intestinal environment. The positive effects of this treatment on clinically significant outcomes remain to be investigated.

Treatment outcomes of infants with cyanotic congenital heart disease treated with synbiotics

OBJECTIVES

The goal was to investigate the effect of orally administered synbiotics on outcome of infants with cyanotic congenital heart disease (CCHD).

METHODS

A prospective, blinded, randomized controlled trial was conducted to evaluate the effect of synbiotics on outcome of infants with CCHD. The infants with CCHD were assigned randomly to 2 groups. Infants in the study group were given synbiotic (Bifidobacterium lactis plus inulin) added to breast milk or mixed feeding until discharge or death. Infants in the placebo group were fed with breast milk or mixed feeding. The outcome measurements were nosocomial sepsis, necrotizing enterocolitis (NEC; Bell stage ≥ 2), length of NICU stay, and death.

RESULTS

A total of 100 infants were enrolled in the trial: 50 in each arm. There were 9 cases of culture-proven sepsis (18%) in the placebo group and 2 cases (4%) in the synbiotic group (P = .03). Length of NICU stay did not differ between the groups (26 [14-36] vs 32 days [20-44], P = .07]. There were 5 cases of NEC (10%) in the placebo group and none in the synbiotic group (P = .03). The incidence of death was lower in synbiotic group (5 [10%] of 50 vs 14 [28.0%] of 50, respectively; P = .04).

CONCLUSIONS

Synbiotics administered enterally to infants with CCHD might reduce the incidence of nosocomial sepsis, NEC, and death.

Probiotic administration in congenital heart disease: a pilot study

OBJECTIVE

To investigate the impact of probiotic Bifidobacterium longum ssp. infantis on the fecal microbiota and plasma cytokines in neonates with congenital heart disease.

STUDY DESIGN

Sixteen infants with congenital heart disease were randomly assigned to receive either B. infantis (4.2 × 10(9) colony-forming units two times daily) or placebo for 8 weeks. Stool specimens from enrolled infants and from six term infants without heart disease were analyzed for microbial composition. Plasma cytokines were analyzed weekly in the infants with heart disease.

RESULTS

Healthy control infants had increased total bacteria, total Bacteroidetes and total bifidobacteria compared to the infants with heart disease, but there were no significant differences between the placebo and probiotic groups. Plasma interleukin (IL)10, interferon (IFN)γ and IL1β levels were transiently higher in the probiotic group.

CONCLUSION

Congenital heart disease in infants is associated with dysbiosis. Probiotic B. infantis did not significantly alter the fecal microbiota. Alterations in plasma cytokines were found to be inconsistent.