Microbial therapeutic interventions

Association of toll-like receptors with the airway-intestinal microbiota and pneumonia development in preterm infants - A case control study

BACKGROUND

The prevention and treatment of pneumonia and lung injury in preterm infants are major challenges for pediatricians worldwide. Few studies have analyzed the composition of bacterial colonies in the airway and intestine and their relationship with toll-like receptors (TLRs) as it relates to pneumonia in preterm infants.

METHODS

This study included 70 infants born at 32-35 weeks gestation. Oral-tracheal aspirates at the time of birth, first-pass meconium, and serum specimens were collected. Bacterial deoxyribonucleic acid (DNA) was extracted from the Oral-tracheal aspirates and meconium, and 16S ribosomal ribonucleic acid (rRNA) genes were amplified and sequenced. The levels of TLR2 and TLR4 were analyzed using an enzyme-linked immunosorbent assay. Preterm infants were classified into non-pneumonia (A) and pneumonia (B) groups according to their clinical manifestations.

RESULTS

Significant differences in the alpha and beta diversities were observed between the two groups. Infants with pneumonia had less bacterial diversity in the airways and intestinal flora at birth than those without pneumonia. The three most predominant phyla in the airways at birth were Proteobacteria, Firmicutes, and Actinobacteria. The levels of TLR2 and TLR4 in oral-tracheal aspirates were higher in infants with pneumonia than in those without pneumonia, although serum TLR2 and TLR4 levels did not differ between the groups. Streptococcus in the oral tracheal aspirate was negatively correlated with TLR2 and TLR4 levels, and Ureaplasma in the oral-tracheal aspirate was negatively correlated with TLR4 levels in the airway.

CONCLUSION

Reduced perinatal microbiota diversity is associated with the levels of TLR2 and TLR4, and may also have a significant impact on the development of pneumonia.

Preterm Infants' Airway Microbiome: A Scoping Review of the Current Evidence

The aim of this scoping review was to investigate and synthesize existing evidence on the airway microbiome of preterm infants to outline the prognostic and therapeutic significance of these microbiomes within the preterm population and identify gaps in current knowledge, proposing avenues for future research. We performed a scoping review of the literature following the Arskey and O'Malley framework. In accordance with our inclusion criteria and the intended purpose of this scoping review, we identified a total of 21 articles. The investigation of the airway microbiome in preterm infants has revealed new insights into its unique characteristics, highlighting distinct dynamics when compared to term infants. Perinatal factors, such as the mode of delivery, chorioamnionitis, the respiratory support, and antibiotic treatment, could impact the composition of the airway microbiome. The 'gut-lung axis', examining the link between the lung and gut microbiome as well as modifications in respiratory microbiome across different sites and over time, has also been explored. Furthermore, correlations between the airway microbiome and adverse outcomes, such as bronchopulmonary dysplasia (BPD), have been established. Additional research in neonatal care is essential to understand the early colonization of infants' airways and explore methods for its optimization. The critical opportunity to shape long-term health through microbiome-mediated effects likely lies within the neonatal period.

Inferring early-life host and microbiome functions by mass spectrometry-based metaproteomics and metabolomics

Humans have a long-standing coexistence with microorganisms. In particular, the microbial community that populates the human gastrointestinal tract has emerged as a critical player in governing human health and disease. DNA and RNA sequencing techniques that map taxonomical composition and genomic potential of the gut community have become invaluable for microbiome research. However, deriving a biochemical understanding of how activities of the gut microbiome shape host development and physiology requires an expanded experimental design that goes beyond these approaches. In this review, we explore advances in high-throughput techniques based on liquid chromatography-mass spectrometry. These omics methods for the identification of proteins and metabolites have enabled direct characterisation of gut microbiome functions and the crosstalk with the host. We discuss current metaproteomics and metabolomics workflows for producing functional profiles, the existing methodological challenges and limitations, and recent studies utilising these techniques with a special focus on early life gut microbiome.

Determinants of the lung microbiome in intubated premature infants at risk for bronchopulmonary dysplasia

BACKGROUND

Airway dysbiosis in premature infants may be associated with bronchopulmonary dysplasia (BPD). Early oropharyngeal colostrum (OPC) administration alters the oral microbiome, which may impact the lung microbiome. We aim to compare the oral and tracheal microbiota during the first week of life, and to determine whether early OPC administration affects microbial diversity or leukocyte inflammatory activity in the lung.

METHODS

Intubated premature infants (n = 42) were evaluated. The oral microbiome was characterized on day of life (DOL) 3, and the tracheal microbiome on DOL 3 and DOL 7, using 16S ribosomal DNA sequencing. Gene expression for inflammatory markers was quantified in airway leukocytes by real-time q-PCR.

RESULTS

The oral and tracheal microbiota were significantly different on DOL 3, but the tracheal microbiome on DOL 7 was more similar to the oral from DOL 3. Tracheal bacterial diversity decreased from DOL 3 to DOL 7. Longer time to first OPC administration tended to be associated with lower bacterial diversity in the airways.

CONCLUSIONS

The tracheal microbiome in intubated premature infants in the first week is likely determined, in part, by the composition of the oral microbiome. Bacterial diversity in intubated babies decreases during the first week of life, a pattern that could be consistent with risk for BPD. Decreased bacterial diversity and increased inflammatory activity in the lung may also be associated with delayed administration of OPC.

Effects of prebiotics on sepsis, necrotizing enterocolitis, mortality, feeding intolerance, time to full enteral feeding, length of hospital stay, and stool frequency in preterm infants: a meta-analysis

BACKGROUND/OBJECTIVES

Prebiotics are increasingly recognized as an effective measure to promote health and prevent adverse health outcomes in preterm infants. We aimed to systematically review the randomized controlled trials (RCTs) in this area.

SUBJECTS/METHODS

Relevant studies from January 2000 to June 2018 were searched and selected from PubMed, Medline, Scopus, and the Cochrane Library. RCTs were included if they involved preterm infant participants, included a prebiotic intervention group, measured incidence of sepsis, feeding intolerance, mortality, time to full enteral feeding, necrotizing enterocolitis (NEC), length of hospital stay, and stool frequency as outcomes.

RESULTS

Eighteen RCTs (n = 1322) were included in the final meta-analysis. Participants who took prebiotics showed significant decreases in the incidence of sepsis (with a risk ratio (RR) of 0.64, 95% CI: 0.51, 0.78), mortality (RR = 0.58. 95% CI: 0.36, 0.94), length of hospital stay (mean difference (MD): -5.18, 95% CI: -8.94, -1.11), and time to full enteral feeding (MD: -0.99, 95% CI: -1.15, 0.83). The pooled effects showed no significant differences between intervention and control groups in relation to the morbidity rate of NEC (RR = 0.79, 95% CI: 0.44, 1.44) or feeding intolerance (RR = 0.87, 95% CI: 0.52, 1.45).

CONCLUSIONS

The results showed that the use of prebiotics with preterm infants is safe and can decrease the incidence of sepsis, mortality, length of hospital stay, and time to full enteral feeding but not NEC.

The Neonatal Microbiome: Implications for Neonatal Intensive Care Unit Nurses

Nursing care of the neonate in the neonatal intensive care unit (NICU) is complex, due in large part to various physiological challenges. A newer and less well-known physiological consideration is the neonatal microbiome, the community of microorganisms, both helpful and harmful, that inhabit the human body. The neonatal microbiome is influenced by the maternal microbiome, mode of infant birth, and various aspects of NICU care such as feeding choice and use of antibiotics. The composition and diversity of the microbiome is thought to influence key health outcomes including development of necrotizing enterocolitis, late-onset sepsis, altered physical growth, and poor neurodevelopment. Nurses in the NICU play a key role in managing care that can positively influence the microbiome to promote more optimal health outcomes in this vulnerable population of newborns.

Insights into study design and statistical analyses in translational microbiome studies

Research questions in translational microbiome studies are substantially more complex than their counterparts in basic science. Robust study designs with appropriate statistical analysis frameworks are pivotal to the success of these translational studies. This review considers how study designs can account for heterogeneous phenotypes by adopting representative sampling schemes for recruiting the study population and making careful choices about the control population. Advantages and limitations of 16S profiling and whole-genome sequencing, the two primary techniques for measuring the microbiome, are discussed followed by an overview of bioinformatic processing of high-throughput sequencing data from these measurements. Practical insights into the downstream statistical analyses including data processing and integration, variable transformations, and data exploration are provided. The merits of regularization and ensemble modeling for analyzing microbiome data are discussed along with a recommendation for selecting modeling approaches based on data-driven simulations and objective evaluation. The review builds on several recent discussions of study design issues in microbiome research but with a stronger emphasis on the downstream and often-ignored aspects of statistical analyses that are crucial for bridging the gap between basic science and translation.

Evolutionary and ecological forces that shape the bacterial communities of the human gut

Since microbes were first described in the mid-1600s, we have come to appreciate that they live all around and within us with both beneficial and detrimental effects on nearly every aspect of our lives. The human gastrointestinal tract is inhabited by a dynamic community of trillions of bacteria that constantly interact with each other and their human host. The acquisition of these bacteria is not stochastic but determined by circumstance (environment), host rules (genetics, immune state, mucus, etc), and dynamic self-selection among microbes to form stable, resilient communities that are in balance with the host. In this review, we will discuss how these factors lead to formation of the gut bacterial community and influence its interactions with the host. We will also address how gut bacteria contribute to disease and how they could potentially be targeted to prevent and treat a variety of human ailments.