Study of the Vaginal Microbiota in Healthy Women of Reproductive Age

An updated study of the relationship between bacterial infections and women's immune system, focusing on bacterial compositions with successful pregnancy

Genital tract infections can cause a variety of harmful health outcomes, including endometritis, bacterial vaginosis, and pelvic inflammatory disease, in addition to infertility. Anaerobic bacteria, such as Gardnerella vaginalis, Megasphaera spp., and Atopobium vaginae, are more commonly identified in cases of bacterial vaginosis than lactobacilli. It is unknown how the microorganisms that cause pelvic inflammatory diseases and endometritis enter the uterus. Both prospective and retrospective research have connected pelvic inflammatory disorders, chronic endometritis, and bacterial vaginosis to infertility. Similar to bacterial vaginosis, endometritis-related infertility is probably caused by a variety of factors, such as inflammation, immune system recognition of sperm antigens, bacterial toxins, and a higher risk of STDs. Preconception care for symptomatic women may include diagnosing and treating pelvic inflammatory disease, chronic endometritis, and bacterial vaginosis before conception to optimize the results of both natural and assisted reproduction.

Perinatal group A streptococcal infection in vagina and its impact on pregnancy outcomes

OBJECTIVE

To investigate the prevalence, antimicrobial susceptibility, and the effects on pregnancy and neonatal outcomes of Group A Streptococcal (GAS) infections in the vagina of perinatal women.

METHODS

From June 2020 to October 2022, 270 perinatal pregnant women underwent vaginal swabs for GAS culture. The antibiotic sensitivity of the positive strains was assessed. Based on GAS detection results, the patients were divided into an observation group (GAS positive) and a control group (GAS negative). Clinical data from both groups were collected to compare the vaginal microecological changes. The adverse outcomes for pregnancy and infants in both groups were retrospectively analyzed. Univariate and multivariate analyses were used to identify the risk factors for adverse outcomes.

RESULTS

Among the 270 pregnant women, 30 tested positive for GAS and 240 tested negative, with a colonization rate of 11.1%. No resistance to penicillin, ampicillin, linezolid, vancomycin, or tigecycline was found among the GAS strains. The resistance rates to tetracycline and clindamycin were 73.3% and 70.0%, respectively. Higher vaginal pH (≥4.5), and increased incidences of bacterial vaginitis, aerobic vaginitis, and microecological imbalances were observed in the observation group compared to the control group (all P<0.05). The observation group also experienced more adverse pregnancy and infant outcomes, such as chorioamnionitis, postpartum infections, fetal distress, and neonatal pneumonia (all P<0.05). Univariate and multivariate analyses indicated that a vaginal pH≥4.5 and microecological imbalance were positively associated with poor maternal and infant outcomes in women with GAS infections (all P<0.05).

CONCLUSIONS

The study found no β-lactam resistant GAS strains. Additionally, a higher vaginal pH (≥4.5) and microecological imbalance were linked to an increased risk of adverse pregnancy and infant outcomes in women with GAS infections.

Lactobacillus as probiotics: opportunities and challenges for potential benefits in female reproductive health

The growing interest of the scientific community in the study of probiotics has gathered valuable data about its beneficial effects for multiple clinical conditions. This data also provides evidence for the functions and properties of probiotics and how they contribute to health benefits by influencing normal microbiota. Lactobacillus is an important genus which has long been utilized in the food industry and is also found as normal oral, intestinal and vaginal microbiota. Lactobacillus has shown multiple health benefits but its relative importance as a probiotic is majorly explored for gastrointestinal health. Healthy vaginal microbiota typically harbors Lactobacillus spp. providing several health benefits for female reproductive health, but there is more data required in order to compare the relative benefits with probiotic Lactobacillus added through either natural food sources or with standard probiotics supplements. The present article discusses the current status of knowledge about vaginal Lactobacillus as a probiotic and also compares the potential of probiotics from natural sources and through supplements along with recent approaches in this area.

Temporal and spatial differences in the vaginal microbiome of Chinese healthy women

Background

Up the reproductive tract, there are large differences in the composition of vaginal microbes. Throughout the menstrual cycle, the structure of the vaginal microbiome shifts. Few studies have examined both in combination. Our study was designed to explore trends in the microbiome of different parts of the vagina in healthy women over the menstrual cycle.

Methods

We performed metagenomic sequencing to characterize the microbiome differences between the cervical orifice and mid-vagina throughout the menstrual cycle.

Results

Our results showed the vaginal microbiome of healthy women in the cervical orifice and the mid-vagina was similar during the periovulatory and luteal phases, with Lactobacillus being the dominant bacteria. In the follicular phase, Acinetobacter was detected in the cervical orifice. From the follicular phase to the luteal phase, the community state types (all five community status types were defined as CSTs) in samples No. 10 and No. 11 changed from CST III to CST I. In addition, the composition of the vaginal microbiome in healthy women from different regions of China was significantly different. We also detected viruses including Human alphaherpesvirus 1 (HSV-1) during periovulatory phase.

Conclusion

This study is valuable for understanding whether the microbial composition of the vagina is consistent in different parts of the menstrual cycle.

The Importance of a Healthy Microbiome in Pregnancy and Infancy and Microbiota Treatment to Reverse Dysbiosis for Improved Health

BACKGROUND

The microbiome of newborn infants during the first 1000 days, influenced early on by their mothers' microbiome health, mode of delivery and breast feeding, orchestrates the education and programming of the infant's immune system and determines in large part the general health of the infant for years.

METHODS

PubMed was reviewed for maternal infant microbiome health and microbiota therapy in this setting with prebiotics, probiotics, vaginal seeding and fecal microbiota transplantation (FMT).

RESULTS

A healthy nonobese mother, vaginal delivery and strict breast feeding contribute to microbiome health in a newborn and young infant. With reduced microbiome diversity (dysbiosis) during pregnancy, cesarean delivery, prematurity, and formula feeding contribute to dysbiosis in the newborn. Microbiota therapy is an important approach to repair dysbiosis in pregnant women and their infants. Currently available probiotics can have favorable metabolic effects on mothers and infants, but these effects are variable. In research settings, reversal of infant dysbiosis can be achieved via vaginal seeding or FMT. Next generation probiotics in development should replace current probiotics and FMT.

CONCLUSIONS

The most critical phase of human microbiome development is in the first 2-3 years of life. Preventing and treating dysbiosis during pregnancy and early life can have a profound effect on an infant's later health.

Profiling of vaginal Lactobacillus jensenii isolated from preterm and full-term pregnancies reveals strain-specific factors relating to host interaction

Each year, 15 million infants are born preterm (<37 weeks gestation), representing the leading cause of mortality for children under the age of five. Whilst there is no single cause, factors such as maternal genetics, environmental interactions, and the vaginal microbiome have been associated with an increased risk of preterm birth. Previous studies show that a vaginal microbiota dominated by Lactobacillus is, in contrast to communities containing a mixture of genera, associated with full-term birth. However, this binary principle does not fully consider more nuanced interactions between bacterial strains and the host. Here, through a combination of analyses involving genome-sequenced isolates and strain-resolved metagenomics, we identify that L. jensenii strains from preterm pregnancies are phylogenetically distinct from strains from full-term pregnancies. Detailed analysis reveals several genetic signatures that distinguish preterm birth strains, including genes predicted to be involved in cell wall synthesis, and lactate and acetate metabolism. Notably, we identify a distinct gene cluster involved in cell surface protein synthesis in our preterm strains, and profiling the prevalence of this gene cluster in publicly available genomes revealed it to be predominantly present in the preterm-associated clade. This study contributes to the ongoing search for molecular biomarkers linked to preterm birth and opens up new avenues for exploring strain-level variations and mechanisms that may contribute to preterm birth.

The Management of Recurrent Urinary Tract Infection: Non-Antibiotic Bundle Treatment

Recurrent urinary tract infections (rUTIs) are a common condition with high morbidity and negatively impact the quality of life. They account for approximately 25% of all antibiotic prescriptions and are a public health concern in an era of increasing multidrug-resistant organisms (MDROs). Several non-antibiotic treatment strategies have been tried to curb antimicrobial use, and many are effective to some degree, but no experience testing multimodal interventions. We created a "care bundle" consisting of behavioral interventions, vaginal and oral probiotics, D-mannose, and cranberry to be followed for six months. We enrolled women with rUTIs over three years. Changes in urinary tract infections, antibiotic use, chronic symptoms, and quality of life were compared in the six months before and after participation in the study. Forty-seven women were enrolled in the study, six of whom were excluded from the final analysis. We observed a 76% reduction in urinary tract infections (p < 0.001) and a reduction in total antibiotic exposure of more than 90% (p < 0.001); all chronic symptoms showed a trend toward reduction. Adherence to the bundle was high (87.2%). Overall, 80.5% of women experienced an improvement in their quality of life. In our experience, a bundle protocol is effective in reducing recurrences and antimicrobial use in a cohort of women with rUTIs and results in a subjective improvement in chronic symptoms and quality of life. Further research with larger sample size is needed to confirm these findings.

The Interplay between Candida albicans, Vaginal Mucosa, Host Immunity and Resident Microbiota in Health and Disease: An Overview and Future Perspectives

Vulvovaginal candidiasis (VVC), which is primarily caused by Candida albicans, is an infection that affects up to 75% of all reproductive-age women worldwide. Recurrent VVC (RVVC) is defined as >3 episodes per year and affects nearly 8% of women globally. At mucosal sites of the vagina, a delicate and complex balance exists between Candida spp., host immunity and local microbial communities. In fact, both immune response and microbiota composition play a central role in counteracting overgrowth of the fungus and maintaining homeostasis in the host. If this balance is perturbed, the conditions may favor C. albicans overgrowth and the yeast-to-hyphal transition, predisposing the host to VVC. To date, the factors that affect the equilibrium between Candida spp. and the host and drive the transition from C. albicans commensalism to pathogenicity are not yet fully understood. Understanding the host- and fungus-related factors that drive VVC pathogenesis is of paramount importance for the development of adequate therapeutic interventions to combat this common genital infection. This review focuses on the latest advances in the pathogenic mechanisms implicated in the onset of VVC and also discusses novel potential strategies, with a special focus on the use of probiotics and vaginal microbiota transplantation in the treatment and/or prevention of recurrent VVC.

In Vitro Screen of Lactobacilli Strains for Gastrointestinal and Vaginal Benefits

Traditional probiotics comprise mainly lactic acid bacteria that are safe for human use, tolerate acid and bile, and adhere to the epithelial lining and mucosal surfaces. In this study, one hundred commercial and non-commercial strains that were isolated from human feces or vaginal samples were tested with regards to overall growth in culture media, tolerance to acid and bile, hydrogen peroxide (H₂O₂) production, and adhesion to vaginal epithelial cells (VECs) and to blood group antigens. As a result, various of the tested lactobacilli strains were determined to be suitable for gastrointestinal or vaginal applications. Commercial strains grew better than the newly isolated strains, but tolerance to acid was a common property among all tested strains. Tolerance to bile varied considerably between the strains. Resistance to bile and acid correlated well, as did VEC adhesion and H₂O₂ production, but H₂O₂ production was not associated with resistance to bile or acid. Except for L. iners strains, vaginal isolates had better overall VEC adhesion and higher H₂O₂ production. Species- and strain-specific differences were evident for all parameters. Rank-ordered clustering with nine clusters was used to identify strains that were suitable for gastrointestinal or vaginal health, demonstrating that the categorization of strains for targeted health indications is possible based on the parameters that were measured in this study.

Human milk microbial species are associated with infant head-circumference during early and late lactation in Guatemalan mother-infant dyads

Human milk contains abundant commensal bacteria that colonize and establish the infant's gut microbiome but the association between the milk microbiome and head circumference during infancy has not been explored. For this cross-sectional study, head-circumference-for-age-z-scores (HCAZ) of vaginally delivered breastfed infants were collected from 62 unrelated Mam-Mayan mothers living in eight remote rural communities in the Western Highlands of Guatemala during two stages of lactation, 'early' (6-46 days postpartum, n = 29) or 'late' (109-184 days postpartum, n = 33). At each stage of lactation, infants were divided into HCAZ ≥ -1 SD (early: n = 18; late: n = 14) and HCAZ < -1 SD (early: n = 11; late: n = 19). Milk microbiome communities were assessed using 16S ribosomal RNA gene sequencing and DESeq2 was used to compare the differential abundance (DA) of human milk microbiota with infant HCAZ subgroups at both stages of lactations. A total of 503 ESVs annotated 256 putative species across the 64 human milk samples. Alpha-diversity using Chao index uncovered a difference in microbial community richness between HCAZ ≥ -1 SD and HCAZ < -1 SD groups at late lactation (p = 0.045) but not at early lactation. In contrast, Canonical Analysis of Principal Coordinates identified significant differences between HCAZ ≥ -1 SD and HCAZ < -1 SD at both stages of lactation (p = 0.003); moreover, 26 milk microbial taxa differed in relative abundance (FDR < 0.05) between HCAZ ≥ -1 SD and HCAZ < -1 SD, with 13 differentially abundant at each lactation stage. Most species in the HCAZ ≥ -1 SD group were Streptococcus species from the Firmicutes phylum which are considered human colonizers associated with human milk whereas the HCAZ < -1 SD group at late lactation had more differentially abundant taxa associated with environmentally and 'potentially opportunistic' species belonging to the Actinobacteria genus. These findings suggest possible associations between brain growth of breastfed infants and the milk microbiome during lactation. Importantly, these data provide the first evidence of cross talk between the human milk microbiome and the infant brain that requires further investigation.

Acidic Electrolyzed Water Inhibits the Viability of Gardnerella spp. via Oxidative Stress Response

The vaginal microbiota, dominated by Lactobacilli, plays an important role in maintaining women's health. Disturbance of the vaginal microbiota allows infection by various pathogens such as Gardnerella spp. (GS) and related anaerobic bacteria resulting in bacterial vaginosis (BV). At present, the treatment options for BV are extremely limited. Treatment of antibacterial drugs and vaginal acidification are the two primary therapeutic methods. Acid electrolyzed water (AEW) is known to inactivate microorganisms and is considered a medical application in recent years. Studies have found that Lactobacillus acidophilus (LA) probiotics helps to inhibit GS-induced BV. Our study took GS and LA as the research object, which aims to explore AEW as a potential alternative therapy for BV and its underlying mechanisms. We first obtained the pH of AEW (3.71–4.22) close to normal vaginal pH (3.8–4.5) to maintain normal vaginal acidification conditions. Plate counting experiments showed that AEW (pH: 4.07, ORP: 890.67, ACC: 20 ppm) (20 ppm) could better inhibit the viability of GS but had a more negligible effect on LA. Then, we preliminarily explored the possible mechanism of AEW anti-GS using cell biology experiments and transmission electron microscopy. Results showed that the membrane permeability was significantly increased and the integrity of cell membrane was destroyed by AEW in GS than those in LA. AEW also caused protein leakage and cell lysis in GS without affecting LA. Meanwhile, AEW induced a number of reactive oxygen species (ROS) production in GS, with no obvious LA changes. Finally, we found that 20 ppm AEW exhibited excellent antibacterial effect on the vaginal secretions of women diagnosed with BV by Amsel criteria and sialic acid plum method. Taken together, our findings manifest that 20 ppm AEW has an excellent antibacterial effect in GS with less effect on LA, which might be expected to become a potential therapy for BV.

Contribution of Lactobacillus iners to Vaginal Health and Diseases: A Systematic Review

Lactobacillus iners, first described in 1999, is a prevalent bacterial species of the vaginal microbiome. As L. iners does not easily grow on de Man-Rogosa-Sharpe agar, but can grow anaerobically on blood agar, it has been initially overlooked by traditional culture methods. It was not until the wide application of molecular biology techniques that the function of L. iners in the vaginal microbiome was carefully explored. L. iners has the smallest genome among known Lactobacilli and it has many probiotic characteristics, but is partly different from other major vaginal Lactobacillus species, such as L. crispatus, in contributing to the maintenance of a healthy vaginal microbiome. It is not only commonly present in the healthy vagina but quite often recovered in high numbers in bacterial vaginosis (BV). Increasing evidence suggests that L. iners is a transitional species that colonizes after the vaginal environment is disturbed and offers overall less protection against vaginal dysbiosis and, subsequently, leads to BV, sexually transmitted infections, and adverse pregnancy outcomes. Accordingly, under certain conditions, L. iners is a genuine vaginal symbiont, but it also seems to be an opportunistic pathogen. Further studies are necessary to identify the exact role of this intriguing species in vaginal health and diseases.