Probiotics in neonatal intensive care - back to the future

Use of probiotics in the NICU: Evaluating the stability of a three-strain probiotic blend in various media for enteral feeding

BACKGROUND

There is little published data on how to prepare probiotic supplements for enteral delivery in the NICU. The objective of this study was to determine how a three-strain probiotic blend (Bb-02, TH-4® and BB-12®) would behave when mixed and held for 4 hours with saline water, sterile water, dextrose 5% in water (D5W), 24 kcal preterm formula, and human milk.

METHODS

A packet of a three-strain probiotic supplement was mixed with 3 mL of saline water, sterile water, D5W, 24 kcal preterm formula, and human milk (tested at 3 mL and 2 mL). Samples were stored at room temperature for 60 minutes then refrigerated for 180 minutes. Probiotic survival, using quantitative enumeration, and pH were monitored over 4 hours. Samples were passed through a 5 French (Fr) feeding tube at the end of the study to evaluate viscosity.

RESULTS

The largest variation in total cell count from 0-time was sterile water with a + 0.26 log(CFU)/mL change at 90 minutes and typical variation is considered±0.50 log units indicating no significant change between samples in 4 hours. Saline water had the lowest final pH at 4.88. All samples easily passed through a 5 Fr feeding tube.

CONCLUSION

The study showed minimal change in cell counts across solutions for 4 hours of storage, indicating health care facilities may be able to prepare probiotic supplements with a variety of solutions in pharmacies or milk rooms. This allows greater flexibility for probiotic delivery to preterm infants.

Changes in the Composition of the Gut Microbiota and the Blood Transcriptome in Preterm Infants at Less than 29 Weeks Gestation Diagnosed with Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a common chronic lung condition in preterm infants that results in abnormal lung development and leads to considerable morbidity and mortality, making BPD one of the most common complications of preterm birth. We employed RNA sequencing and 16S rRNA gene sequencing to profile gene expression in blood and the composition of the fecal microbiota in infants born at <29 weeks gestational age and diagnosed with BPD in comparison to those of preterm infants that were not diagnosed with BPD. 16S rRNA gene sequencing, performed longitudinally on 255 fecal samples collected from 50 infants in the first months of life, identified significant differences in the relative levels of abundance of Klebsiella, Salmonella, Escherichia/Shigella, and Bifidobacterium in the BPD infants in a manner that was birth mode dependent. Transcriptome sequencing (RNA-Seq) analysis revealed that more than 400 genes were upregulated in infants with BPD. Genes upregulated in BPD infants were significantly enriched for functions related to red blood cell development and oxygen transport, while several immune-related pathways were downregulated. We also identified a gene expression signature consistent with an enrichment of immunosuppressive CD71+ early erythroid cells in infants with BPD. Intriguingly, genes that were correlated in their expression with the relative abundances of specific taxa in the microbiota were significantly enriched for roles in the immune system, suggesting that changes in the microbiota might influence immune gene expression systemically.IMPORTANCE Bronchopulmonary dysplasia (BPD) is a serious inflammatory condition of the lung and is the most common complication associated with preterm birth. A large body of evidence now suggests that the gut microbiota can influence immunity and inflammation systemically; however, the role of the gut microbiota in BPD has not been evaluated to date. Here, we report that there are significant differences in the gut microbiota of infants born at <29 weeks gestation and subsequently diagnosed with BPD, which are particularly pronounced when infants are stratified by birth mode. We also show that erythroid and immune gene expression levels are significantly altered in BPD infants. Interestingly, we identified an association between the composition of the microbiota and immune gene expression in blood in early life. Together, these findings suggest that the composition of the microbiota may influence the risk of developing BPD and, more generally, may shape systemic immune gene expression.

Primary prevention of ROP and the oxygen saturation targeting trials

Reducing the burden of visual morbidity from retinopathy of prematurity (ROP) begins with primary prevention, and improvements in neonatal care with a positive impact on ROP are possible in all settings. Strategies range from rigorous adoption of inexpensive evidence-based protocols, for example on temperature control, prevention of sepsis and support for breast-milk feeding, through to comprehensive quality improvement programmes, and fostering team work and camaraderie. Oxygen monitoring is essential for very preterm infants receiving supplementary oxygen. The Neonatal Oxygenation Prospective Meta-analysis (NeOProM) collaboration has reported analysis of five trials of oxygen saturation (SpO₂) targeting in very preterm infants and shown that a SpO₂ target of 85-89% compared to 91-95% was associated with increased mortality (on average 28 extra deaths for every 1000 infants treated). Adopting a SpO₂ target higher than 85-89% might increase the risk of ROP for some infants, highlighting the importance of pursuing all other means of prevention.

Arguments against routine administration of probiotics for NEC prevention

PURPOSE OF REVIEW

Necrotizing enterocolitis (NEC) is a leading cause of morbidity and mortality among premature neonates. Although randomized trials have shown that probiotics may be efficacious in the prevention of NEC, their use has not been universally adopted in the neonatal intensive care unit (NICU). Caveats regarding routine probiotic supplementation for the prevention of NEC are summarized in this review.

RECENT FINDINGS

Accumulating evidence indicates that prophylactic probiotic supplementation in preterm infants can reduce the incidence of NEC. However, substantial knowledge gaps, regulatory issues, and implementation challenges should be addressed before probiotics are introduced as standard of care for all preterm neonates. Limitations of published trial data have made it challenging to define regimens that optimize efficacy and safety in specific patient subgroups. Moreover, the current probiotic market lacks rigorous regulatory oversight, which could raise concerns about the quality and safety of probiotic products. Finally, implementation pitfalls include risks of cross-colonization and resource requirements to monitor and mitigate potential adverse events.

SUMMARY

Probiotics have shown promise in the prevention of NEC. However, there is insufficient evidence to guide the selection of optimal regimens. Furthermore, issues related to regulatory and institutional oversight should be addressed before supplementation is routinely implemented in NICUs.

Para-probiotics for Preterm Neonates-The Next Frontier

Current evidence supports the use of probiotics in preterm neonates for prevention of necrotizing enterocolitis, mortality and late onset sepsis. Despite the strong evidence, the uptake of this intervention has not been universal due to concerns including probiotic sepsis, pro-inflammatory response and transmission of antibiotic resistance. Critically ill extremely preterm neonates with potentially compromised gut integrity are at higher risk of probiotic sepsis due to translocation. In most countries, probiotics are sold as food supplements with poor quality control. The traditional definition of probiotics as &ldquo;live microorganisms&rdquo; has been challenged as many experts have questioned the importance of viability in the context of the beneficial effects of probiotics. Paraprobiotics (ghost probiotics), are defined as non-viable microbial cells (intact or broken) or crude cell extracts (i.e., with complex chemical composition), which, when administered (orally or topically) in adequate amounts, confer a benefit on the human or animal consumer. Current evidence indicates that paraprobiotics could be safe alternatives to probiotics in preterm neonates. High-quality pre-clinical and clinical studies including adequately powered randomised controlled trials (RCTs) are warranted in preterm neonates to explore this new frontier.

Lactobacillus murinus HF12 colonizes neonatal gut and protects rats from necrotizing enterocolitis

The use of lactobacilli in prevention of necrotizing enterocolitis (NEC) is hampered by insufficient knowledge about optimal species/strains and effects on intestinal bacterial populations. We therefore sought to identify lactobacilli naturally occurring in postnatal rats and examine their ability to colonize the neonatal intestine and protect from NEC. L. murinus, L. acidophilus, and L. johnsonii were found in 42, 20, and 1 out of 51 4-day old rats, respectively. Higher proportion of L. murinus in microbiota correlated with lower NEC scores. Inoculation with each of the three species during first feeding significantly augmented intestinal populations of lactobacilli four days later, indicating successful colonization. L. murinus, but not L. acidophilus or L. johnsonii, significantly protected against NEC. Thus, lactobacilli protect rats from NEC in a species- or strain-specific manner. Our results may help rationalizing probiotic therapy in NEC.

The viability of probiotics in water, breast milk, and infant formula

The aim of this study was to determine bacteriological stability of a probiotic mixture dispersed in various diluents. The commercially available probiotic (Infloran®), containing Bifidobacterium bifidum (10⁹ CFU/250 mg tablet) and Lactobacillus acidophilus (10⁹ CFU/250 mg tablet), was dispersed within expressed breast milk, sterile water, and infant formula and examined at temperatures of 4 and 21 °C. When stored at 4 °C, significant decreases (P < 0.05) in the level of L. acidophilus and B. bifidum were observed in expressed breast milk and sterile water after a 6-h period. However, when stored in infant formula, both strains remained stable over a 12-h period. When stored at 21 °C, a significant decrease (P < 0.05) was observed in the level of L. acidophilus in sterile water, expressed breast milk and infant formula throughout a 12-h period. However, no significant decrease was observed overtime in B. bifidum in all three diluents at this temperature.

CONCLUSION

Our findings suggest that, when stored at 4 °C, this probiotic product can remain at a stable condition for 6 h in sterile water and infant formula; however, the viability of the probiotic decreases significantly after this period of time. Administration of this probiotic in sterile water can be an acceptable alternative to dispersion and administration in expressed breast milk. What is Known: • Administration of probiotics containing lactobacilli and bifidobacteria has become more widespread in neonatology, mainly as prophylaxis for the prevention of necrotising entercolitis in preterm infants. • Probiotic reconstitution, from its powder base, is not standardized and various diluents, including sterile water, breast milk, and infant formula, have been used. What is New: • When stored at 4 °C, a probiotic containing lactobacilli and bifidobacteria remains at a stable microbological condition for up to 6 h in sterile water. • Administration of this probiotic dispersed in sterile water, followed by an EBM feed, can be an acceptable alternative to dispersion and administration in EBM.

Bifidobacterium breve M-16V as a Probiotic for Preterm Infants: A Strain-Specific Systematic Review

INTRODUCTION

Bifidobacterium breve M-16V has been used as a probiotic in preterm infants. Probiotic strain-specific data are essential to guide clinical practice.

OBJECTIVE

To assess effects of B breve M-16V in preterm neonates.

DESIGN

A systematic review of randomized controlled trials (RCTs) and non-RCTs of B breve M-16V in preterm infants was conducted. Multiple databases, proceedings of Pediatric Academy Society, and other relevant conferences were searched in September 2016 and on January 5, 2017.

RESULTS

Five RCTs (n = 482) and 4 non-RCTs (n = 2496) were included. Of the 5 RCTs, 4 carried high/unclear risk of bias in many domains. Meta-analysis (fixed effects model) of RCTs showed no significant benefits on stage ≥2 necrotizing enterocolitis, late-onset sepsis, mortality, and postnatal age at full feeds. Meta-analysis of non-RCTs showed significant benefits on (1) late-onset sepsis-3 studies (n = 2452), odds ratio = 0.56 (95% CI, 0.45-0.71), P < .0001; (2) mortality-2 studies (n = 2319), odds ratio = 0.61 (95% CI, 0.44-0.84), P = .002; and (3) postnatal age at full feeds (days)-2 studies (n = 361), mean difference, -2.42 (95% CI, -2.55 to -2.3), P < .00001. There were no adverse effects from B breve M-16V. On Grading of Recommendations, Assessment, Development, and Evaluation analysis, the overall quality of evidence was deemed very low.

CONCLUSIONS

Current evidence is limited regarding the potential of B breve M-16V in preterm neonates. Adequately powered, preferably cluster RCTs are needed to confirm these findings.

Benefits of probiotics in preterm neonates in low-income and medium-income countries: a systematic review of randomised controlled trials

OBJECTIVE

Although there is an overall reduction in underfive mortality rate, the progress in reducing neonatal mortality rate has been very slow. Over the last 20 years, preterm births have steadily increased in low-income and medium-income countries (LMICs) particularly in sub-Saharan Africa and South Asia. Preterm birth is associated with increased mortality and morbidity, particularly in LMICs. Based on systematic reviews of randomised controlled trials (RCTs), many neonatal units in high-income countries have adopted probiotics as standard of care for preterm neonates. We aimed to systematically review the safety and efficacy of probiotics in reducing mortality and morbidity in preterm neonates in LMICs.

DESIGN

Systematic review and meta-analysis of RCTs.

DATA SOURCES

Medline, Embase, Cochrane Central Register of Controlled Trials, Cumulative Index of Nursing and Allied Health Literature and E-abstracts from Pediatric Academic Society meetings and other paediatric and neonatal conference proceedings were searched in January 2017.

ELIGIBILITY CRITERIA

RCTs comparing probiotics versus placebo/no probiotic in preterm neonates (gestation<37 weeks) conducted in LMICs.

RESULTS

Total 23 (n=4783) RCTs from 4 continents and 10 LMICs were eligible for inclusion in the meta-analysis using fixed effect model. The risk of necrotising enterocolitis (NEC greater than or equal to stage II) (risk ratio (RR) 0.46 (95% CI 0.34 to 0.61), P<0.00001, numbers needed to treat (NNT) 25 (95% CI 20 to 50)), late-onset sepsis (LOS) (RR 0.80 (95% CI 0.71 to 0.91), P=0.0009, NNT 25 (95% CI 17 to 100)) and all-cause mortality (RR 0.73 (95% CI 0.59 to 0.90), P=0.003, NNT 50 (95% CI 25 to 100)) were significantly lower in probiotic supplemented neonates. The results were significant on random effects model analysis and after excluding studies with high risk of bias. No significant adverse effects were reported.

CONCLUSION

Probiotics have significant potential to reduce mortality and morbidity (eg, NEC, LOS) in preterm neonates in LMICs.

Necrotizing enterocolitis in premature infants and newborns

Necrotizing enterocolitis (NEC) is the most common acquired disease of the gastrointestinal tract (GIT) in premature infants and newborns. It is defined as an ulcerative inflammation of the intestinal wall. The clinical signs of incipient NEC are often very discrete, and range from localized intestinal symptoms to generalized signs of sepsis. NEC is classified depending on its severity into disease states according to the modified Bell's Classification. Treatment of NEC ranges, depending on its severity, from a conservative therapeutic approach to surgery with resection of the affected parts of the intestine. Mortality is considerably high in extremely small preterm infants reaching up to 42% of the affected children. Measures such as breastfeeding or alternatively nutrition with pasteurized human donor milk from a milk bank, administration of probiotics, avoidance of histamine type II receptor antagonists, and restrictive antibiotic treatment should be considered early on for prevention of NEC.

The microbiome in early life: implications for health outcomes

Recent studies have characterized how host genetics, prenatal environment and delivery mode can shape the newborn microbiome at birth. Following this, postnatal factors, such as antibiotic treatment, diet or environmental exposure, further modulate the development of the infant's microbiome and immune system, and exposure to a variety of microbial organisms during early life has long been hypothesized to exert a protective effect in the newborn. Furthermore, epidemiological studies have shown that factors that alter bacterial communities in infants during childhood increase the risk for several diseases, highlighting the importance of understanding early-life microbiome composition. In this review, we describe how prenatal and postnatal factors shape the development of both the microbiome and the immune system. We also discuss the prospects of microbiome-mediated therapeutics and the need for more effective approaches that can reconfigure bacterial communities from pathogenic to homeostatic configurations.

Survey and evidence based review of probiotics used in very low birth weight preterm infants within the United States

OBJECTIVE

Data from multiple clinical trials, mostly conducted outside the US, indicate that probiotic prophylaxis is an effective intervention for prevention of necrotizing enterocolitis (NEC) in preterm infants. Probiotics are routinely used in many countries. However, in the US, probiotic use in preterm infants is limited (6.7% of very low birth weight (VLBW) infants in the US were exposed to probiotics in 2014, Vermont Oxford Network (VON)). Probiotic products are often considered in 'generic' terms, but considerable variation exists between commercially available probiotics in terms of their quantity and quality. The study objectives were to identify the probiotic products used in VLBW infants within the US, and to determine whether their use was supported by reliable evidence.

STUDY DESIGN

A phone survey of all neonatal intensive care units (NICU) participating in VON within the US was conducted between May and September 2015 to identify NICUs that are using probiotics in VLBW infants. Data was collected regarding specific probiotic brands, timing, dose and duration of probiotic use. An evidence based literature search, limited to randomized controlled trials in VLBW infants, was conducted to determine whether the use of identified probiotics were supported by reliable evidence.

RESULTS

There was a 70.3% (500/711) response rate to the phone survey. During the survey period, 14.0% of NICUs were using probiotics in VLBW infants (70/500). Probiotics were routinely given to all VLBW infants in 8.8% (44/500) NICUs, while it was given in selected VLBW infants in 5.2% (26/500) of NICUs. The common indications for selective use of probiotics were feeding intolerance and antibiotic use. Sixteen commercial probiotics products were identified through the phone survey. Probiotic products most commonly used were Culturelle (27.1%), Biogaia (14.3%), Gerber Soothe (14.3%) and Florababy (8.6%). The literature search identified evidence that evaluated 4/16 probiotic products identified (Culturelle, Align, Biogaia and ABC Dophilus). Only ABC Dophilus was reported to have a protective effect against NEC, but is used sparingly in US NICUs (2.9%).

CONCLUSIONS

The probiotics use in VLBW infants within the US is increasing, but is still limited. There was no evidence for safety or efficacy of 90% of the probiotics currently used in US NICUs, and therefore, caution is warranted.

Probiotic supplementation for preventing invasive fungal infections in preterm neonates--a systematic review and meta-analysis

Invasive fungal infections (IFI) are associated with significant health burden in preterm neonates. The objective of this study was to systematically review effect of probiotic supplementation (PS) for preventing IFI in preterm neonates. We searched Cochrane Central Register of Controlled Trials, Medline, Embase, Cumulative Index of Nursing and Allied Health Literature, and proceedings of the Pediatric Academic Society meetings in August 2014. Study selection was performed on randomised controlled trials (RCT) of PS in neonates born <37 weeks. Primary outcome of this study was IFI (Isolation of fungus in blood/body fluids) and secondary outcome was fungal gut colonisation. Information on IFI/colonisation was available in 8 of 27 RCT. Meta-analysis (fixed effects model) showed that PS reduced the risk of IFI (RR: 0.50, 95% CI: 0.34, 0.73, I(2) = 39%). Results were not significant with random effects model (RR: 0.64, 95%, CI: 0.30, 1.38, P = 0.25, I(2) = 39%). Analysis after excluding the study with a high baseline incidence (75%) of IFI showed that PS had no significant benefits (RR: 0.89; 95% CI: 0.44, 1.78). Of the five studies reporting on fungal gut colonisation, three reported benefits of probiotics; two did not. Current evidence is limited to derive firm conclusions on the effect of PS for preventing IFI/gut colonisation in preterm neonates.

Probiotic Supplementation and Late-Onset Sepsis in Preterm Infants: A Meta-analysis

CONTEXT

Late-onset sepsis (LOS) is a major cause of mortality and morbidity in preterm infants. Despite various preventive measures, its incidence continues to remain high, hence the urgent need for additional approaches. One such potential strategy is supplementation with probiotics. The updated Cochrane Review (2014) did not find benefits of probiotics in reducing the risk of LOS in preterm infants (19 studies, N = 5338). Currently there are >30 randomized controlled trials (RCTs) of probiotics in preterm infants that have reported on LOS.

OBJECTIVES

To conduct a systematic review including all relevant RCTs.

DATA SOURCES

PubMed, Embase, Cochrane Central Register of Controlled Trials, Cumulative Index of Nursing and Allied Health Literature, and E-abstracts from the Pediatric Academic Society meetings and other pediatric and neonatal conference proceedings were searched in June and August 2015.

STUDY SELECTION

RCTs comparing probiotics versus placebo/no probiotic were included.

DATA EXTRACTION

Relevant data were extracted independently by 3 reviewers.

RESULTS

Pooled results from 37 RCTs (N = 9416) using fixed effects model meta analysis showed that probiotics significantly decreased the risk of LOS (675/4852 [13.9%] vs 744/4564 [16.3%]; relative risk, 0.86; 95% confidence interval, 0.78-0.94; P = .0007; I(2) = 35%; number needed to treat, 44). The results were significant even after excluding studies with high risk of bias.

CONCLUSIONS

Probiotic supplementation reduces the risk of LOS in preterm infants.