Maternal-neonatal transmission of Enterococcus strains during delivery

Non-faecium non-faecalis enterococci: a review of clinical manifestations, virulence factors, and antimicrobial resistance

SUMMARYEnterococci are a diverse group of Gram-positive bacteria that are typically found as commensals in humans, animals, and the environment. Occasionally, they may cause clinically relevant diseases such as endocarditis, septicemia, urinary tract infections, and wound infections. The majority of clinical infections in humans are caused by two species: Enterococcus faecium and Enterococcus faecalis. However, there is an increasing number of clinical infections caused by non-faecium non-faecalis (NFF) enterococci. Although NFF enterococcal species are often overlooked, studies have shown that they may harbor antimicrobial resistance (AMR) genes and virulence factors that are found in E. faecium and E. faecalis. In this review, we present an overview of the NFF enterococci with a particular focus on human clinical manifestations, epidemiology, virulence genes, and AMR genes.

Exploring the Diet-Gut Microbiota-Epigenetics Crosstalk Relevant to Neonatal Diabetes

Neonatal diabetes (NDM) is a rare monogenic disorder that presents as hyperglycemia during the first six months of life. The link between early-life gut microbiota dysbiosis and susceptibility to NDM remains uncertain. Experimental studies have demonstrated that gestational diabetes mellitus (GDM) could develop into meconium/gut microbiota dysbiosis in newborns, and thus, it is thought to be a mediator in the pathogenesis of NDM. Epigenetic modifications have been considered as potential mechanisms by which the gut microbiota and susceptibility genes interact with the neonatal immune system. Several epigenome-wide association studies have revealed that GDM is associated with neonatal cord blood and/or placental DNA methylation alterations. However, the mechanisms linking diet in GDM with gut microbiota alterations, which may in turn induce the expression of genes linked to NDM, are yet to be unraveled. Therefore, the focus of this review is to highlight the impacts of diet, gut microbiota, and epigenetic crosstalk on altered gene expression in NDM.

Untargeted metabolite profiling of Enterococcus villorum SB2, isolated from the vagina of pregnant women, by HR-LCMS

Enterococcus bacteria are studied in various sectors including fermentation, food and dairy industries,as well as studied for their probiotic properties but have limited use due to their possible pathogenic behavior. The present report talks about the metabolites produced, by the previously isolated Enterococcus strain, E.villorum SB2 (accession number KX830968), from the vaginal source. The growth of the bacteria in three types of media (M17, MRS and LAPTg) was compared, where the M17 media gave better bacterial colonies, also maximum growth rate was observed in M17 media (T_d = 1.6 h & k = 0.4 h^-1), and thus was selected as the metabolite production media. Further, the studied bacteria did not show any hemolytic activity, making it safe for industrial applications. The HR-LCMS results showed the production of various amino acids, organic acids, peptides, and other metabolites like flavonoids (Quercetin 3-O-Manoglucoside), terpenoids (7',8',Dihydro-8'-hydroxycitraniaxanthin, O-Methylganoderic acid O, Thalicsessine, Austinol, Valdiate), indole derivatives produced by tryptophan metabolism (5-hydroxykynurenamine, 2S,4R)-4-(9H-Pyrido[3,4-b]indol-1-yl)-1,2,4-butanetriol, Indoleacrylic acid), antimicrobial compounds (Fortimicin A) and fatty acids (Stearic acid, Myristic acid), which were earlier unreported form Enterococcus species opening new scope for discovering new industrial applications of the strain. As the studied bacteria has been reported to be a potential probiotic, the detection of these industrially important metabolites can be studied further in future studies to reveal the potential industrial applications of the strain.

Perinatal Gram-Positive Bacteria Exposure Elicits Distinct Cytokine Responses In Vitro

During pregnancy, infections caused by the gram-positive bacteria Enterococcus faecalis (E. faecalis), Streptococcus agalacticae (S. agalacticae), and Staphylococcus aureus (S. aureus) are major reasons for preterm labor, neonatal prematurity, meningitis, or sepsis. Here, we propose cytokine responses to bacterial infections by the immature perinatal immune system as central players in the pathogenesis of preterm birth and neonatal sepsis. We aimed to close the gap in knowledge about such cytokine responses by stimulating freshly isolated umbilical blood mononuclear cells (UBMC) with lysates of E. faecalis, S. agalacticae, and S. aureus collected from pregnant women in preterm labor. Bacterial lysates and, principally, S. aureus and S. agalacticae distinctly triggered most of the eleven inflammatory, anti-inflammatory, TH₁/TH₂ cytokines, and chemokines quantified in UBMC culture media. Chemokines depicted the most robust induction. Among them, MIP-1β was further enhanced in UBMC from female compered to male newborn infants. Due to its stability and high levels, we investigated the diagnostic value of IL-8. IL-8 was critically upregulated in cord blood of preterm neonates suffering from infections compared to gestational age-matched controls. Our results provide novel clues about perinatal immunity, underscoring a potential value of IL-8 for the timely detection of infections and suggesting that MIP-1β constitutes an early determinant of sex-specific immunity, which may contribute, e.g., to male’s vulnerability to preterm birth.

Spray drying studies of probiotic Enterococcus strains encapsulated with whey protein and maltodextrin

Background

Probiotic Enterococcus strains of human origin were microencapsulated by spray drying using whey protein and maltodextrin as an encapsulating agent. The obtained encapsulates were characterized for stability, viability, and physiological properties.

Results

The microcapsules were prepared from probiotic Enterococcus strains that were previously isolated from human vagina and infants’ meconium. The microcapsules revealed similar particle sizes and morphologies. The highest hygroscopicity was observed in the microcapsules produced with strain E. rivorum S22C (0.17 ± 1.15) g water/kg powder/min. E. canintestini S18A revealed highest dissolution time in water (703 ± 2 s). The DSC thermogram revealed excellent thermal stability of all microcapsules. The physicochemical and morphological characteristics of the microcapsules were acceptable with regard to residual water content, particle mean size, and thermophysical properties and storage stability under room temperature conditions, with a low inactivation rate of Enterococcus strains. All the microcapsules revealed the recommended count of probiotic cells, low moisture content with low water activity. Observation under a scanning electron microscope revealed spherical-shaped partially collapsed structures measuring between 9 and 14 μm with surface concavities.

Conclusions

The microcapsule probiotic strains of Enterococcus microencapsulated by spray drying using whey protein and maltodextrin revealed properties of acceptable standards. These strains can have future potential as developing probiotic animal feed and food industry.