Probiotics to prevent necrotising enterocolitis and nosocomial infection in very low birth weight preterm infants

Evidence on the benefits of probiotics for preterm infants

Introduction

This article reviews the evidence for the use of different strains of probiotics in the prevention of prevalent pathologies in premature neonates. A systematic review was conducted of the use of probiotics in neonates with less than 37 weeks of gestational age, based on a search for systematic reviews and observational and experimental studies performed during the period from January 2014 to February 2021. For this purpose, the PubMed, MEDLINE and Cochrane Library databases were consulted. The aim of this article was to review the existing data on the relationship between the administration of probiotics (with different strains and doses) and the risk of necrotising enterocolitis, mortality, late sepsis and other disease parameters in premature infants. The literature search obtained 240 articles, of which we selected 16, representing a total sample of over 200,000 premature infants. Analysis of the data obtained reveals statistical evidence that the combined administration of probiotics (especially of Lactobacillus and Bifidobacterium strains) reduces the incidence of grade II or higher necrotising enterocolitis, all-cause mortality, late sepsis, length of hospital stay and time until complete enteral nutrition is achieved. However, no benefits were apparent with respect to alleviating bronchopulmonary dysplasia, retinopathy of prematurity or intraventricular haemorrhage. Further research is needed to determine the most appropriate strains, doses and treatment duration for preterm infants to achieve the health benefits identified.

Lactobacillus rhamnosus GG as a probiotic for preterm infants: a strain specific systematic review and meta-analysis

Lactobacillus rhamnosus GG (LGG) is a widely used and extensively researched probiotic. Probiotic effects are considered to be strain specific. We aimed to comprehensively assess the strain-specific effects of LGG in preterm infants. A systematic review of RCTs and non-RCTs to evaluate the effect of LGG in preterm infants. We followed the Cochrane methodology, and preferred reporting items for systematic reviews (PRISMA) statement for conducting and reporting this review. We searched the Cochrane central register of controlled trials, PubMed, EMBASE and CINAHL databases till December 2023. The review was registered in PROSPERO 2022 CRD42022324933. Meta-analysis of data from RCTs that used LGG as the sole probiotic showed significantly lower risk of NEC ≥Stage II [5 RCTs, n = 851, RR:0.50 (95% CI: 0.26, 0.93), P = 0.03] in the LGG group. There was no significant difference in the risk of LOS [7 RCTs, n = 1037, RR:1.08 (95% CI 0.84, 1.39), P = 0.55], mortality [3 RCTs, n = 207, RR: 0.99 (95% CI: 0.42, 2.33), P = 0.99], time to reach full feeds [2 RCTs, n = 19, SMD = 0.11 days (95% CI: -0.22, 0.45), P = 0.51] and duration of hospital stay [3 RCTs, n = 293, SMD: -0.14 days (95% CI: -0.37 to 0.09), P = 0.23]. Meta-analysis of data from non-RCTs showed no significant effect of LGG on NEC, LOS, and mortality. RCTs showed beneficial effects of LGG when used as the sole probiotic in reducing the risk of NEC, whereas observational studies did not. Strain-specific systematic review of LGG provides important data for guiding research and clinical practice.

Breast-feeding as protective factor against bronchopulmonary dysplasia in preterm infants

Breast-feeding is associated with fewer comorbidities in very-low-birth-weight (VLBW) preterm infants. Bronchopulmonary dysplasia (BPD) of VLBW infants is a multifactorial pathology in which nutritional aspects may be of special importance. The aim of this study is to determine, in a cohort of VLBW infants, whether breast milk nutrition is associated with a reduced prevalence and severity of BPD. A retrospective study was conducted to record the intake of mother's own milk (MOM), pasteurised donor human milk or preterm formula milk in the first 2 weeks of postnatal life of 566 VLBW newborns at our hospital during the period January 2008-December 2021. After applying the relevant exclusion criteria, data for 489 VLBW infants were analysed; 195 developed some degree of BPD. Moderate or severe BPD is associated with less weight gain. Moreover, the preferential ingestion of breast milk in the first and second postnatal weeks had effects associated with lower OR for BPD, which were statistically demonstrable for mild (OR 0·16; 95 % CI 0·03, 0·71) and severe (OR 0·08; 95 % CI 0·009, 0·91) BPD. Breast-feeding during the first weeks of postnatal life is associated with a reduced prevalence of BPD, which is frequently associated with less weight gain as a result of greater respiratory effort with greater energy expenditure.

Probiotics to prevent necrotizing enterocolitis and reduce mortality in neonates: A meta-analysis

BACKGROUND

Probiotics are gradually being used as a supplementation to prevent necrotizing enterocolitis (NEC) and reduce mortality in neonates. We performed an updated meta-analysis to systematically evaluate the efficacy and safety of prophylactic probiotic supplementation for preventing NEC.

METHODS

The databases including PubMed, Embase, Scopus, Web of Science, and China National Knowledge Infrastructure were used to search the relevant articles. The latest retrieval date was up to December 2021. The meta-analysis was performed using Stata version 10.0. Finally, a total of 70 studies containing 8319 cases and 9283 controls were included. The strength of the association between the supplementation of probiotics and NEC was measured by risk ratios (RRs) with 95% confidence intervals (CIs). Pooled effect sizes across studies were performed by a random effect model.

RESULTS

The results showed that the probiotics could significantly reduce the incidence of NEC (stage II or more) (RR = 0.436, 95% CI = 0.357-0.531, P < .001), the overall mortality (RR = 0.651, 95% CI = 0.506-0.836, P < .001), and NEC-related mortality (RR = 0.639, 95% CI = 0.423-0.966, P = .034). Due to the lack of sufficient sample size, we did not perform the subgroup analysis by types of probiotic strain.

CONCLUSION

This meta-analysis indicates that the use of probiotics can effectively reduce the occurrence of NEC and mortality in neonates.

Reducing Risk Factors for Necrotizing Enterocolitis: What Is the Recent Evidence and Biologic Plausibility Supporting Probiotics?

BACKGROUND

Development of necrotizing enterocolitis is multifactorial, with contributing factors that are unique to the preterm infant in the neonatal intensive care unit (NICU). The use of probiotics may reduce these risk factors.

PURPOSE

To evaluate evidence of biologic plausibility for probiotic supplementation to mitigate key risk factors implicated in the development of disease and show recent evidence of safety and effectiveness.

DATA SOURCES

A literature survey of electronic databases, including PubMed, Cochrane Database of Systematic Reviews, and CINAHL, was conducted.

STUDY SELECTION

Selection terms included "necrotizing enterocolitis," "probiotics," and "prematurity." Reviews that were included were full text, in English, and published in the last 5 years. Ten systematic reviews of randomized controlled trials were extracted from 749 records. Excluded were studies that used adjuncts to probiotics, such as lactoferrin or prebiotics, and studies of probiotics given antenatally.

DATA EXTRACTION

Two independent reviewers extracted data to AMSTAR 2, a critical appraisal tool for systematic reviews of randomized or nonrandomized studies of healthcare interventions.

RESULTS

All the reviews found statistically significant reductions in necrotizing enterocolitis rates after supplementation with probiotics. None of the reviews reported adverse effects.

IMPLICATION FOR PRACTICE AND RESEARCH

Probiotic supplementation with specific strains reduces risk for necrotizing enterocolitis. To advance probiotic use in the NICU, additional high-quality trials are needed to focus on specific strains or combinations of strains and to evaluate dosing and duration of treatment.Video Abstract available athttps://journals.lww.com/advancesinneonatalcare/Pages/videogallery.aspx .

Necrotising enterocolitis, late-onset sepsis and mortality after routine probiotic introduction in the UK

OBJECTIVE

To compare necrotising enterocolitis (NEC), late-onset sepsis (LOS), focal intestinal perforation (FIP) and mortality in infants from a single neonatal unit before and after probiotic introduction.

DESIGN

Retrospective review of infants <32 weeks admitted January 2009-December 2012 (no probiotic) and January 2013-December 2017 (routine probiotics). Infants included were admitted before day 3, and not transferred out before day 3. NEC, LOS and FIP were defined with standard definitions.

PATIENTS

1061 infants were included, 509 preprobiotic and 552 postprobiotic. Median gestation, birth weight and antenatal steroid use did not differ, and proportions of extremely low birthweight infants were similar (37% and 41%).

RESULTS

Overall unadjusted risk of NEC (9.2% (95% CI 7.1 to 12.1) vs 10.6% (95% CI 8.2 to 13.4), p=0.48), LOS (16.3% (95% CI 13.2 to 19.6) vs 14.1% (95% CI 11.5 to 17.4), p=0.37) and mortality (9.2% (95% CI 7.1 to 12.1) vs 9.7% (95% CI 7.6 to 12.6), p=0.76) did not differ, nor proportion of surgical NEC. In multiple logistic regression, accounting for gestation, birth weight, antenatal steroid, maternal milk, chorioamnionitis and sex, probiotic receipt was not significantly associated with NEC (adjusted OR (aOR) 1.08 (95% CI 0.71 to 1.68), p=0.73), LOS or mortality. In subgroup (645 infants) >28 weeks, aOR for NEC in the probiotic cohort was 0.42 (95% CI 0.2 to 0.99, p=0.047). FIP was more common in the probiotic cohort (OR 2.3 (95% CI 1.0 to 5.4), p=0.04), not significant in regression analysis (2.11 (95% CI 0.97 to 4.95), p=0.05).

CONCLUSIONS

Probiotic use in this centre did not reduce overall mortality or rates of NEC, LOS or FIP but subgroup analysis identified NEC risk reduction in infants >28 weeks, and LOS reduction <28 weeks.

Effectiveness of two probiotics in preventing necrotising enterocolitis in a cohort of very-low-birth-weight premature new-borns

According to previous research, the incidence of necrotising enterocolitis (NEC) decreases after supplementation with probiotics. However, few studies have considered the equivalence or otherwise of different strains of probiotics in this respect. Accordingly, this prospective observational study was conducted in a cohort of 245 very-low-birth-weight (VLBW) new-borns to assess the prevalence of NEC after supplementation with the probiotic Inforan^® (Berna Biotech, Madrid, Spain) 250 mg capsules containing 10⁹ cfu of Lactobacillus acidophilus (ATCC 4356) and 10⁹ cfu of Bifidobacterium bifidum (ATCC 15696); or with Bivos^® (Ferring, Madrid, Spain) containing Lacticaseibacillus (formerly Lactobacillus) rhamnnosus (LGG) (ATCC 53103) (10⁹ cfu); or with no probiotic supplementation. Statistical analysis was performed using multivariant regression for the duration of parenteral nutrition, length of neonatal intensive care unit stay, use of oxygen therapy and presence of chorioamnionitis. Of the VLBW new-borns in the study group, 65 received Infloran, 108 received Bivos and 72 received no probiotic. A significant association was observed between a reduced presence of NEC Stage ≥2 and probiotic supplementation. The odds risk (OR) obtained was 0.174 (95% confidence interval (CI): 0.032-0.936) for Infloran and 0.196 (95%CI: 0.053-0.732) for Bivos. Therefore, both probiotics are associated with a lower prevalence of NEC in VLBW new-borns, with no significant differences.

Prophylactic Probiotic Supplementation for Preterm Neonates-A Systematic Review and Meta-Analysis of Nonrandomized Studies

Systematic review and meta-analyses of randomized controlled trials (RCTs) show that probiotics reduce the risk of necrotizing enterocolitis (NEC ≥ Stage II), late onset sepsis (LOS), all-cause mortality, and feeding intolerance in preterm neonates. Data from observational studies is important to confirm probiotic effects in clinical practice. We aimed to compare outcomes before and after implementing routine probiotic supplementation (RPS) in preterm neonates (<37 weeks of gestation) by performing a systematic review of non-RCTs using Cochrane methodology. Databases including PubMed, The Cumulative Index to Nursing and Allied Health Literature (CINAHL), Embase, Cochrane Central library, and Google Scholar were searched in May 2020. A meta-analysis was performed using a random effects model. Categorical measure of effect size was expressed as OR and 95% CI. Statistical heterogeneity was assessed by the chi-squared test, I2 statistic. The level of evidence (LOE) was summarized using GRADE (Grading of Recommendations Assessment, Development, and Evaluation) guidelines. Primary outcomes were NEC ≥ Stage II, LOS, and all-cause mortality. Secondary outcomes included probiotic sepsis. Thirty good-quality non-RCTs (n = 77,018) from 18 countries were included. The meta-analysis showed RPS was associated with significantly reduced: 1) NEC ≥ Stage II (30 studies, n = 77,018; OR: 0.60; 95% CI: 0.50, 0.73; P <0.00001, I2: 65%; LOE: Moderate), 2) LOS: (21 studies, n = 65,858; OR: 0.85; 95% CI: 0.74, 0.97; P = 0.02, I2: 74%; LOE: Low), and 3) all-cause mortality (27 non-RCTs, n = 70,977; OR: 0.77; 95% CI: 0.68, 0.88; P = 0.0001, I2: 49%; LOE: Low). Subgroups: 1) extremely low birth weight (ELBW: birth weight <1000 g) neonates: RPS was associated with significantly reduced NEC ≥ Stage II (4.5% compared with 7.9%). However, there was no difference in LOS and mortality. 2) Multistrain RPS was more effective than single strain. One study reported 3 nonfatal cases of probiotic sepsis. In summary, moderate- to low-quality evidence indicates that RPS was associated with significantly reduced NEC ≥ Stage II, LOS, and all-cause mortality in neonates <37 weeks of gestation and NEC ≥ Stage II in ELBW neonates.

Probiotics and Human Milk Oligosaccharides in Premature Infants

Intestinal dysbiosis precedes and is a likely causative factor in necrotizing enterocolitis (NEC) and many cases of late-onset sepsis. Randomized controlled trials and observational cohort studies demonstrate decreased risk of NEC, sepsis, and death with the administration of probiotic microbes and decreased risk of NEC and sepsis with feeding of human milk. Animal studies suggest promising mechanisms by which probiotic microbes and human milk oligosaccharides alter the composition of the intestinal microbiota and may prevent disease in premature infants. Inclusion of parents in discussions of the risks and benefits of human milk and probiotics for premature infants is essential.

Probiotics' efficacy in paediatric diseases: which is the evidence? A critical review on behalf of the Italian Society of Pediatrics

During the last decade several paediatric studies have been published with different possible indications for probiotics, leading to a global increase of probiotics' market. Nevertheless, different study designs, multiple single/combined strains and small sample size still leave many uncertainties regarding their efficacy. In addition, different regulatory and quality control issues make still very difficult the interpretation of the clinical data. The objective of this review is to critically summarise the current evidence on probiotics' efficacy and safety on a different number of pathologies, including necrotizing enterocolitis, acute infectious diarrhoea, allergic diseases and functional gastrointestinal disorders in order to guide paediatric healthcare professionals on using evidence-based probiotics' strains. To identify relevant data, literature searches were performed including Medline-PubMed, the Cochrane Library and EMBASE databases. Considering probiotics strain-specific effects, the main focus was on individual probiotic strains and not on probiotics in general.

Mixed probiotics decrease the incidence of stage II-III necrotizing enterocolitis and death: A systematic review and meta-analysis

BACKGROUND

Necrotizing enterocolitis (NEC) is a major cause of morbidity and mortality in premature infants. In order to evaluate the efficacy of probiotics in the prevention of stage II-III NEC, we performed a meta-analysis of clinical studies.

METHODS

We searched in PubMed, Medline and Embase from 1 January 1990 to 16 January 2018. Heterogeneity was examined by Q-test. Publication bias was evaluated by funnel plot and Egger's regression test.

RESULTS

30 articles were identified meeting the inclusion criteria. Data showed that probiotics supplement could significantly reduce the risk of stage II-III NEC (RR = 0.51, 95% CI, 0.38 to 0.67, P < 0.001) and death rate (RR = 0.69, 95% CI, 0.55 to 0.87, P = 0.002). The mixed probiotics and lactobacillus could reduce the risk of stage II-III NEC (for mixed probiotics, RR = 0.39, 95% CI, 0.26 to 0.57; for lactobacillus, RR = 0.53, 95% CI, 0.36 to 0.78), while bifidobacterium or saccharomyces did not have such effect. The results also indicated that only the mixed probiotics could reduce the risk of deaths (RR = 0.52, 95%CI, 0.34 to 0.80). Subgroup analysis for mortality revealed that probiotics had significant effect in Asian region (RR = 0.54, 95% CI, 0.37 to 0.80, P = 0.002) but not in non-Asian region (RR = 0.84, 95% CI, 0.66 to 1.08, P = 0.179).

CONCLUSIONS

Probiotics could significantly decrease the risk of stage II-III NEC and death. Compared to using single probiotics species, the application of combining different probiotics has a better efficacy in the prevention of stage II-III NEC and death, especially in the Asian population.

Historical aspects of probiotic use to prevent necrotising enterocolitis in preterm babies

Over the last few decades, numerous studies have evaluated probiotic use for the prevention of necrotising enterocolitis in preterm babies. Early 'proof of concept' studies evaluating whether probiotics are capable of colonising the preterm gut have translated into multiple observational studies, small and large randomised controlled trials. Some show evidence of benefit while others have produced disappointing results. In this paper, we review the history of probiotic use in preterm babies for NEC prevention in an attempt to explain why uncertainty exists and why this intervention has not been universally adopted into routine neonatal practice.

Probiotics and the prevention of necrotizing enterocolitis

BACKGROUND

Immaturity of the host immune system and alterations in the intestinal microbiome appear to be key factors in the pathogenesis of necrotizing enterocolitis (NEC). The aim of this paper is to weigh the evidence for the use of probiotics to prevent NEC in premature infants.

METHODS

Animal studies, randomized controlled trials, observational cohort studies and meta-analyses involving administration of probiotic products for the prevention of NEC were reviewed. This review of the evidence summarizes the available preclinical and clinical data.

RESULTS

In animal models probiotic microbes alter the intestinal microbiome, decrease inflammation and intestinal permeability and decrease the incidence and severity of experimental NEC. In randomized, placebo-controlled trials and cohort studies of premature infants, probiotic microbes decrease the risk of NEC, death and sepsis.

CONCLUSION

Evidence is strong for the prevention of NEC with the use of combination probiotics in premature infants who receive breast milk. The potential risks and benefits of probiotic administration to premature infants should be carefully reviewed with parents.

TYPE OF STUDY

Therapeutic.

LEVEL OF EVIDENCE

I.

Colonization of preterm gnotobiotic piglets with probiotic Lactobacillus rhamnosus GG and its interference with Salmonella Typhimurium

A balanced microbiota of the gastrointestinal tract (GIT) is a prerequisite for a healthy host. The GIT microbiota in preterm infants is determined by the method of delivery and nutrition. Probiotics can improve the GIT microbiota balance and suitable animal models are required to verify their harmlessness. Preterm gnotobiotic piglets were colonized with Lactobacillus rhamnosus GG (LGG) to evaluate its safety and possible protective action against infection with an enteric pathogen, Salmonella Typhimurium (ST). Clinical signs (anorexia, somnolence, fever and diarrhea), bacterial interference and translocation, intestinal histopathology, transcriptions of claudin-1, occludin and interferon (IFN)-γ, intestinal and systemic protein levels of interleukin (IL)-8, IL-12/23 p40 and IFN-γ were compared among (i) germ-free, (ii) LGG-colonized, (iii) ST-infected and (iv) LGG-colonized and subsequently ST-infected piglets for 24 h. Both LGG and ST-colonized the GIT; LGG translocated in some cases into mesenteric lymph nodes and the spleen but did not cause bacteremia and clinical changes. ST caused clinical signs of gastroenteritis, translocated into mesenteric lymph nodes, the spleen, liver and blood, increased claudin-1 and IFN-γ transcriptions, but decreased occludin transcription and increased local and systemic levels of IL-8 and IL-12/23 p40. Previous colonization with LGG reduced ST colonization in the jejunum and translocation into the liver, spleen and blood. It partially ameliorated histopathological changes in the intestine, reduced IL-8 levels in the jejunum and plasma and IL-12/23 p40 in the jejunum. The preterm gnotobiotic piglet model of the vulnerable preterm immunocompromised infant is useful to verify the safety of probiotics and evaluate their protective effect.

The Interaction of the Gut Microbiota with the Mucus Barrier in Health and Disease in Human

Glycoproteins are major players in the mucus protective barrier in the gastrointestinal and other mucosal surfaces. In particular the mucus glycoproteins, or mucins, are responsible for the protective gel barrier. They are characterized by their high carbohydrate content, present in their variable number, tandem repeat domains. Throughout evolution the mucins have been maintained as integral components of the mucosal barrier, emphasizing their essential biological status. The glycosylation of the mucins is achieved through a series of biosynthetic pathways processes, which generate the wide range of glycans found in these molecules. Thus mucins are decorated with molecules having information in the form of a glycocode. The enteric microbiota interacts with the mucosal mucus barrier in a variety of ways in order to fulfill its many normal processes. How bacteria read the glycocode and link to normal and pathological processes is outlined in the review.

[Research advances in necrotizing enterocolitis in neonates]

Necrotizing enterocolitis (NEC) is a catastrophic disease caused by a variety of factors in neonates, especially preterm infants. Severe NEC has a high fatality rate, and most survivors may face short- and long-term adverse prognosis. Risk factors for NEC include preterm birth, non-breastfeeding, microbial abnormalities in the digestive tract, and ischemia-reperfusion injury. High-resolution abdominal ultrasound helps with the early diagnosis of NEC. The preventive measures for NEC include protecting the intestinal mucosa through nutritional intervention, interfering with intestinal injury signals, changing intestinal microflora, and performing early minimal enteral nutrition. This disease progresses rapidly, and there are still no effective measures. Supportive care is mainly used for the treatment of this disease, and patients in severe conditions may need surgical treatment. Celastrol, lipopolysaccharide, and fecal transplantation help with the treatment of NEC, but further studies are needed to confirm their clinical effects.