A randomized controlled trial of an oral probiotic to reduce antepartum group B Streptococcus colonization and gastrointestinal symptoms

Vaginal and Rectal microbiome changes following administration of a multi-species antenatal probiotic: A randomized control trial

The gut and vaginal microbiome undergo changes during pregnancy which may be protective or harmful to the birthing person. Probiotics have been found to cause protective changes to the gut and vaginal microbiomes, with the potential to improve perinatal outcomes. This randomized control trial compares the vaginal and rectal microbiomes before and after an antenatal probiotic or placebo intervention, with a diverse group of pregnant people and a special focus on racial disparities. The vaginal and rectal microbiomes reveal non-significant increased Lactobacillus in the probiotics group, with a greater increase in participants who identified as Black. Potential implications and future study are discussed.

Re-framing the importance of Group B Streptococcus as a gut-resident pathobiont

Streptococcus agalactiae (Group B Streptococcus, GBS) is a Gram-positive bacterial species that causes disease in humans across the lifespan. While antibiotics are used to mitigate GBS infections, it is evident that antibiotics disrupt human microbiomes (which can predispose people to other diseases later in life), and antibiotic resistance in GBS is on the rise. Taken together, these unintended negative impacts of antibiotics highlight the need for precision approaches for minimizing GBS disease. One possible approach involves selectively depleting GBS in its commensal niches before it can cause disease at other body sites or be transmitted to at-risk individuals. One understudied commensal niche of GBS is the adult gastrointestinal (GI) tract, which may predispose colonization at other body sites in individuals at risk for GBS disease. However, a better understanding of the host-, microbiome-, and GBS-determined variables that dictate GBS GI carriage is needed before precise GI decolonization approaches can be developed. In this review, we synthesize current knowledge of the diverse body sites occupied by GBS as a pathogen and as a commensal. We summarize key molecular factors GBS utilizes to colonize different host-associated niches to inform future efforts to study GBS in the GI tract. We also discuss other GI commensals that are pathogenic in other body sites to emphasize the broader utility of precise de-colonization approaches for mitigating infections by GBS and other bacterial pathogens. Finally, we highlight how GBS treatments could be improved with a more holistic understanding of GBS enabled by continued GI-focused study.

The Promise of Precision Nutrition for Modulation of the Gut Microbiota as a Novel Therapeutic Approach to Acute Graft-versus-host Disease

Acute graft-versus-host disease (aGVHD) is a severe side effect of allogeneic hematopoietic stem cell transplantation (aHSCT) that has complex phenotypes and often unpredictable outcomes. The current management is not always able to prevent aGVHD. A neglected actor in the management of aGVHD is the gut microbiota. Gut microbiota dysbiosis after aHSCT is caused by many factors and may contribute to the development of aGVHD. Diet and nutritional status modify the gut microbiota and a wide range of products are now available to manipulate the gut microbiota (pro-, pre-, and postbiotics). New investigations are testing the effect of probiotics and nutritional supplements in both animal models and human studies, with encouraging results. In this review, we summarize the most recent literature about the probiotics and nutritional factors able to modulate the gut microbiota and we discuss the future perspective in developing new integrative therapeutic approaches to reducing the risk of graft-versus-host disease in patients undergoing aHSCT.

Vaginal microbial dynamics and pathogen colonization in a humanized microbiota mouse model

Vaginal microbial composition is associated with differential risk of urogenital infection. Although Lactobacillus spp. are thought to confer protection against infection, the lack of in vivo models resembling the human vaginal microbiota remains a prominent barrier to mechanistic discovery. Using 16S rRNA amplicon sequencing of C57BL/6J female mice, we found that vaginal microbial composition varies within and between colonies across three vivaria. Noting vaginal microbial plasticity in conventional mice, we assessed the vaginal microbiome of humanized microbiota mice (HMbmice). Like the community structure in conventional mice, HMbmice vaginal microbiota clustered into community state types but, uniquely, HMbmice communities were frequently dominated by Lactobacillus or Enterobacteriaceae. Compared to conventional mice, HMbmice were less susceptible to uterine ascension by urogenital pathobionts group B Streptococcus (GBS) and Prevotella bivia. Although Escherichia and Lactobacillus both correlated with the absence of uterine GBS, vaginal pre-inoculation with exogenous HMbmouse-derived E. coli, but not Ligilactobacillus murinus, reduced vaginal GBS burden. Overall, HMbmice serve as a useful model to elucidate the role of endogenous microbes in conferring protection against urogenital pathogens.

Interspecies Interactions within the Host: the Social Network of Group B Streptococcus

Group B Streptococcus (GBS) is a pervasive neonatal pathogen accounting for a combined half a million deaths and stillbirths annually. The most common source of fetal or neonatal GBS exposure is the maternal microbiota. GBS asymptomatically colonizes the gastrointestinal and vaginal mucosa of 1 in 5 individuals globally, although its precise role in these niches is not well understood. To prevent vertical transmission, broad-spectrum antibiotics are administered to GBS-positive mothers during labor in many countries. Although antibiotics have significantly reduced GBS early-onset neonatal disease, there are several unintended consequences, including an altered neonatal microbiota and increased risk for other microbial infections. Additionally, the incidence of late-onset GBS neonatal disease remains unaffected and has sparked an emerging hypothesis that GBS-microbe interactions in developing neonatal gut microbiota may be directly involved in this disease process. This review summarizes our current understanding of GBS interactions with other resident microbes at the mucosal surface from multiple angles, including clinical association studies, agriculture and aquaculture observations, and experimental animal model systems. We also include a comprehensive review of in vitro findings of GBS interactions with other bacterial and fungal microbes, both commensal and pathogenic, along with newly established animal models of GBS vaginal colonization and in utero or neonatal infection. Finally, we provide a perspective on emerging areas of research and current strategies to design microbe-targeting prebiotic or probiotic therapeutic intervention strategies to prevent GBS disease in vulnerable populations.

Group B streptococcus in obstetrics: unsolved problems

For several decades, among all possible pathogens of neonatal infections, group B streptococcus has been one of the leading positions. Sepsis, meningitis, and pneumonia are among the most common clinical manifestations of neonatal infection associated with group B streptococcus. In this review, our goal was to analyze the literature demonstrating a worldwide approach to the prevention of vertical transmission of group B streptococcus from mother to child. When writing the review, scientific publications of foreign and domestic authors from the PubMed database were studied. The review considers the drugs of choice for intranatal antibiotic prophylaxis, and their pharmacodynamic, and pharmacokinetic features. The analysis details the problem of the growth of resistance of group B streptococcus to antibacterial drugs. The antimicrobial activity of lactoferrin was noted at a minimum inhibitory concentration of 500 μg/ml. The presented review also reflects the protective and therapeutic effects of oral intake of probiotics containing Lactobacillus acidophilus, Lactobacillus salivarius, Lactobacillus rhamnosus GR-1, and Lactobacillus reuteri RC-14 . Based on the analysis, it can be concluded that penicillin G and ampicillin have the most pronounced bactericidal effect against group B streptococcus. At the same time, the most common side effects of β-lactam penicillins include an allergic reaction with the possible development of anaphylactic shock. Given this, the antibiotics of the first-line reserve group include cefazolin, clindamycin, and vancomycin. At the same time, it is important to take into account the decrease in the therapeutic concentration of clindamycin with a change in the alpha-1-acid glycoprotein in the blood of the mother and fetus, the nephrotoxic effect of vancomycin and the cross-a llergic reaction of cefazolin with antibiotics of the penicillin group. A promising direction in solving the problem of group B streptococcus is the development of new strategies for the prevention of perinatal infection of the fetus and newborn based on a more detailed study of the effects of lactoferrin and probiotics.

Vaginal microbial dynamics and pathogen colonization in a humanized microbiota mouse model

Vaginal microbiota composition is associated with differential risk of urogenital infection. Although vaginal Lactobacillus spp. are thought to confer protection through acidification, bacteriocin production, and immunomodulation, lack of an in vivo model system that closely resembles the human vaginal microbiota remains a prominent barrier to mechanistic discovery. We performed 16S rRNA amplicon sequencing of wildtype C57BL/6J mice, commonly used to study pathogen colonization, and found that the vaginal microbiome composition varies highly both within and between colonies from three distinct vivaria. Because of the strong influence of environmental exposure on vaginal microbiome composition, we assessed whether a humanized microbiota mouse ( HMb mice) would model a more human-like vaginal microbiota. Similar to humans and conventional mice, HMb mice vaginal microbiota clustered into five community state types ( h mCST). Uniquely, HMb mice vaginal communities were frequently dominated by Lactobacilli or Enterobacteriaceae . Compared to genetically-matched conventional mice, HMb mice were less susceptible to uterine ascension by urogenital pathobionts group B Streptococcus (GBS) and Prevotella bivia , but no differences were observed with uropathogenic E. coli . Specifically, vaginal Enterobacteriaceae and Lactobacillus were associated with the absence of uterine GBS. Anti-GBS activity of HMb mice vaginal E. coli and L. murinus isolates, representing Enterobacteriaceae and Lactobacillus respectively, were characterized in vitro and in vivo . Although L. murinus reduced GBS growth in vitro , vaginal pre-inoculation with HMb mouse-derived E. coli , but not L. murinus , conferred protection against vaginal GBS burden. Overall, the HMb mice are an improved model to elucidate the role of endogenous microbes in conferring protection against urogenital pathogens.

IMPORTANCE

An altered vaginal microbiota, typically with little to no levels of Lactobacillus , is associated with increased susceptibility to urogenital infections, although mechanisms driving this vulnerability are not fully understood. Despite known inhibitory properties of Lactobacillus against urogenital pathogens, clinical studies with Lactobacillus probiotics have shown mixed success. In this study, we characterize the impact of the vaginal microbiota on urogenital pathogen colonization using a humanized microbiota mouse model that more closely mimics the human vaginal microbiota. We found several vaginal bacterial taxa that correlated with reduced pathogen levels but showed discordant effects in pathogen inhibition between in vitro and in vivo assays. We propose that this humanized microbiota mouse platform is an improved model to describe the role of the vaginal microbiota in protection against urogenital pathogens. Furthermore, this model will be useful in testing efficacy of new probiotic strategies in the complex vaginal environment.

Probiotics in the Sourdough Bread Fermentation: Current Status

Sourdough fermentation is an ancient technique to ferment cereal flour that improves bread quality, bringing nutritional and health benefits. The fermented dough has a complex microbiome composed mainly of lactic acid bacteria and yeasts. During fermentation, the production of metabolites and chemical reactions occur, giving the product unique characteristics and a high sensory quality. Mastery of fermentation allows adjustment of gluten levels, delaying starch digestibility, and increasing the bio-accessibility of vitamins and minerals. This review focuses on the main steps of sourdough fermentation, the microorganisms involved, and advances in bread production with functional properties. The impact of probiotics on human health, the metabolites produced, and the main microbial enzymes used in the bakery industry are also discussed.