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Fecal Microbiota Transplantation in Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Jamshidi, P, Farsi, Y, Nariman, Z, Hatamnejad, MR, Mohammadzadeh, B, Akbarialiabad, H, Nasiri, MJ, Sechi, LA
International journal of molecular sciences. 2023;24(19)
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Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder the cause of which is not yet fully elucidated. Probiotics, prebiotics and dietary changes have been shown to mitigate IBS symptoms whilst the results from studies of faecal microbiota transplants (FMT) have been inconsistent. The aim of this systematic review and meta-analysis of double-blind, randomised controlled trials (RCT) was to evaluate the efficacy and safety of FMT in IBS. 7 RCTs with a low risk of bias and no publication bias were included in the meta-analysis. Overall, no statistically significant effect was observed. A subgroup analysis by treatment modality showed that benefits were seen with lower GI administration of a single dose of multiple-donor FMT. Abdominal pain, nausea, diarrhoea and bloating were the most common adverse events, with no severe or critical adverse events reported. The authors call for larger and longer clinical trials to fill existing knowledge gaps.
Abstract
Irritable bowel syndrome (IBS) poses a significant challenge due to its poorly understood pathogenesis, substantial morbidity, and often inadequate treatment outcomes. The role of fecal microbiota transplantation (FMT) in managing IBS symptoms remains inconclusive. This systematic review and meta-analysis aimed to ascertain the effectiveness of FMT in relieving symptoms in IBS patients. A thorough search was executed on PubMed/Medline and Embase databases until 14 June 2023, including all studies on FMT use in IBS patients. We examined the efficiency of FMT in reducing patients' symptoms overall and in particular subgroups, classified by placebo preparation, FMT preparation, frequency, and route of administration. Among 1015 identified studies, seven met the inclusion criteria for the meta-analysis. The overall symptomatology of FMT-treated IBS patients did not significantly differ from the control group (Odds Ratio (OR) = 0.99, 95% Confidence Interval (CI) 0.39-2.5). Multiple doses of FMT compared with non-FMT placebo, or single-donor FMT therapy compared with autologous FMT placebo also showed no significant benefit (OR = 0.32, 95%CI (0.07-1.32), p = 0.11, and OR = 1.67, 95%CI (0.59-4.67), p = 0.32, respectively). However, a single dose of multiple-donor FMT administered via colonoscopy (lower gastrointestinal (GI) administration) significantly improved patient symptoms compared with autologous FMT placebo (OR = 2.54, 95%CI (1.20-5.37), p = 0.01, and OR = 2.2, 95%CI (1.20-4.03), p = 0.01, respectively). The studies included in the analysis showed a low risk of bias and no publication bias. In conclusion, lower GI administration of a single dose of multiple-donor FMT significantly alleviates patient complaints compared with the autologous FMT used as a placebo. The underlying mechanisms need to be better understood, and further experimental studies are desired to fill the current gaps.
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Effects of Probiotics in Adults with Gastroenteritis: A Systematic Review and Meta-Analysis of Clinical Trials.
Mitra, AK, Asala, AF, Malone, S, Mridha, MK
Diseases (Basel, Switzerland). 2023;11(4)
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Gastroenteritis is a major cause of morbidity and mortality globally and symptoms can range from mild to life-threatening. Some studies have suggested benefits of probiotics in the treatment of gastroenteritis in children whilst in adults, results are inconsistent. The aim of this systematic review and meta-analysis was to evaluate the effects of probiotics on acute and chronic gastroenteritis in adults. 35 clinical trials were included in the systematic review and 22 in the meta-analysis. Of these, 23 dealt with inflammatory bowel disease, 5 with pouchitis, 3 with antibiotic-induced diarrhoea, 2 with Helicobacter pylori infection and one each with diverticulitis and acute watery diarrhoea. 27 (77%) of studies showed some benefits of probiotic administration. The meta-analysis of 22 studies did not show a statistically significant benefit of probiotics. Although statistical analysis showed the studies to be homogenous, the authors point out that studies differed widely in aetiologies and probiotics used. A subgroup analysis of 8 studies in patients with ulcerative colitis also showed no benefit. In all studies, probiotics were well tolerated and no adverse side effects were reported. The authors concluded that further research is needed to help identify the most appropriate use of probiotics for the different types of gastroenteritis.
Expert Review
Conflicts of interest:
None
Take Home Message:
- For chronic inflammatory gastroenteritis conditions in adults, probiotics were effective in treating and preventing relapse
- In ulcerative colitis, probiotics were not effective and adverse events outweighed the benefits
- No safety concerns were found for probiotic use in any studies
- Aetiologies, disease severity and duration as well as the type of probiotics used were widely diverse.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
To date, evidence has been mixed for probiotic effectiveness in gastrointestinal syndromes associated with gastroenteritis. The aim of this study was to review current evidence on the effect of probiotics on gastroenteritis in adults.
Methods
This was a systematic review (n=35; total sample size 4577, median 44) and meta-analysis (n=22) of randomised controlled trials. Quality was assessed using CADIMA as per a rating scale (0 to 4) and standards of critical appraisal.
Results
All 35 studies on gastroenteritis included participants with chronic diarrhoea of diverse aetiologies such as IBD, antibiotic-associated, except one which had acute watery diarrhoea.
51% (n=18) of studies assessed the effects of probiotics in the treatment of ulcerative colitis (UC) and Crohn's disease (CD). 60% (n=21) used multiple strains of probiotics while the rest used single strains. Lactobacilli, Bifidobacteria, Escherichia and Streptococcus were the most common and only a few studies administered probiotics with another conventional treatment.
19 studies (55%) rated highly in terms of quality while 15 (43%) scored moderately. The majority (63%) of the 27 studies where probiotics were shown to be effective were of high quality.
Systematic review results:
- 27/53 studies (77%) showed a favourable response after using probiotics (resolution, improvement, remission or no relapse), mostly in patients with IBDs
- 7 studies (20%) found probiotics to be ineffective
- 1 study was inconclusive
- Multiple strain probiotics (VSL #3) was found to be most effective in IBD
- All administered probiotics were well tolerated with no adverse side effects although caution in immunocompromised patients was mentioned in several studies.
The meta-analysis results:
- Overall effectiveness for 22 studies (p=0.37) highlighted there was not enough evidence that the intervention was more protective than controls.
- Probiotics were not effective in UC (p = 0.28), and adverse events caused by probiotics may outweigh the benefits in studies with UC patients.
Conclusion
While benefits of effectiveness were found for probiotic use in gastroenteritis in adults, results from the systematic review and meta-analysis showed a mixed effect.
Clinical practice applications:
- Based on the systematic review, probiotics may be an effective treatment or adjuvant treatment for gastroenteritis but ineffective for around 20% of patients
- It is worth noting that combined therapy with standard treatment showed effective results
- Beneficial effects of probiotics in other key clinical outcomes including disease prevention, relapse, quality of life, morbidity were found
- While the results are interesting it is difficult to apply them in practice as the type of probiotics used were widely different as were the causes, severity and duration of gastroenteritis.
Considerations for future research:
- Further and larger studies would be beneficial to understand the benefits of probiotics in terms of single therapy or in combination with standard treatment particularly for UC, CDs, gastroenteritis not due to viral infection
- Individual-level data instead of aggregated data could give a better idea of effectiveness of probiotics in the future
- In this study aetiologies and the type, dosage, duration of probiotics used were widely diverse therefore systematic reviews and meta-analysis on specific conditions, specific probiotic strains and combinations would be beneficial.
Abstract
Probiotics have been widely used in gastroenteritis due to acute and chronic illnesses. However, evidence supporting the effectiveness of probiotics in different health conditions is inconclusive and conflicting. The aim of this study was to review the existing literature on the effects of probiotics on gastroenteritis among adults. Only original articles on clinical trials that demonstrated the effects of probiotics in adults with gastroenteritis were used for this analysis. Multiple databases, such as PubMed, Google Scholar, MEDLINE and Scopus databases, were searched for the data. The study followed standard procedures for data extraction using a PRISMA flow chart. A quality appraisal of the selected studies was conducted using CADIMA. Finally, a meta-analysis was performed. Thirty-five articles met the selection criteria; of them, probiotics were found effective in the treatment and/or prevention of chronic inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease in 17 (49%), and the treatment of pouchitis in 4 (11.4%), antibiotic-induced diarrhea in 3 (8.6%), Helicobacter pylori infection in 2 (5.7%) and diverticulitis in 1 (2.9%), while the remaining 7 (20%) were ineffective, and 1 study's results were inconclusive. The meta-analysis did not demonstrate any significant protective effects of probiotics. Having a τ2 value of zero and I2 of 6%, the studies were homogeneous and had minimum variances. Further studies are suggested to evaluate the beneficial effects of probiotics in IBDs and other chronic bowel diseases.
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A meta-analysis of the effects of probiotics on acute pancreatitis.
Hou, X, Yang, J, Zhao, Z, Liu, L
Asian journal of surgery. 2023;46(9):3885-3889
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Acute pancreatitis is an inflammation and dysfunction of the pancreas due to abnormally activated pancreatic enzymes. The aim of this meta-analysis was to evaluate the effects of probiotics on acute pancreatitis. 16 randomised controlled trials including 1,305 patients were included in the meta-analysis. Probiotics led to reductions in the length of hospital stay, the duration of time in the intensive care unit, sepsis and overall infection rate. There were no significant effects on mortality, pancreatic complications, surgery, drainage rate and systemic complications.
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The effect of melatonin on irritable bowel syndrome patients with and without sleep disorders: a randomized double-blinded placebo-controlled trial study.
Faghih Dinevari, M, Jafarzadeh, F, Jabbaripour Sarmadian, A, Abbasian, S, Nikniaz, Z, Riazi, A
BMC gastroenterology. 2023;23(1):135
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Previous research has shown that the use of melatonin by individuals with irritable bowel syndrome (IBS) has improved symptoms and quality of life (QoL) but did not affect sleep. This research has been shown to have some limitations in that it has been conducted in a small number of individuals and did not use the latest IBS diagnostic criteria. This randomised control trial aimed to determine in 136 individuals with IBS with and without sleep disorders the effects of melatonin on IBS score, gastrointestinal (GI) symptoms, QoL, and sleep. The results showed that compared to placebo, the use of melatonin for 8 weeks resulted in improved IBS score and GI symptoms in individuals with and without sleep disorders. Severity and frequency of abdominal pain, satisfaction with bowel habits, disease impacts on life, and stool consistency were all improved, however frequency of defecations was unaffected. Sleep was improved in those with sleep disorders, but not those without. It was concluded that melatonin can be used to improve IBS and QoL in individuals with or without sleep disorders and may also improve sleep in those with sleep disorders and IBS. This study could be used by healthcare professionals to recommend the use of melatonin to individuals with IBS to improve symptoms and QoL.
Abstract
BACKGROUND Irritable bowel syndrome (IBS) is one of the world's most common gastrointestinal (GI) disorders, and current treatments do not meet patients' demands. This study aimed to investigate melatonin's therapeutic effects on IBS score, GI symptoms, quality of life, and sleep parameters in both groups of IBS patients with and without sleep disorders. METHODS In this randomized double-blinded placebo-controlled trial study, 136 patients with a diagnosis of IBS based on ROME IV criteria were enrolled and then divided into two groups respecting having sleep disorders or not. Patients of each group were randomized in a 1:1 ratio to receive melatonin 6 mg daily (3 mg fasting and 3 mg at bedtime) for 2 months (8 weeks). Blocked randomization was used in this process. All patients were evaluated both at the beginning and the end of the trial regarding IBS score, GI symptoms, quality of life, and sleep parameters through valid questionnaires. RESULTS In both groups of patients with and without sleep disorders, a significant improvement was observed in IBS score and GI symptoms, including the severity and the frequency of abdominal pain, the severity of abdominal bloating, satisfaction with bowel habits, disease's impact on patient's life, and stool consistency; however, there was no significant improvement in the frequency of defecations per week. In patients with sleep disorders, significant improvement in sleep parameters, including subjective sleep quality, sleep latency, sleep duration, sleep efficiency, and daytime dysfunction, was observed, while in patients without sleep disorders, there was no significant improvement in sleep parameters. In addition, quality-of-life improvement was observed in a significant number of melatonin recipients compared to placebo in both groups of patients. CONCLUSION Melatonin can be considered an effective treatment for improving IBS score, GI symptoms, and quality of life in IBS patients with and without sleep disorders. It is also effective to improve sleep parameters in IBS patients with sleep disorders. TRIAL REGISTRATION This study has been registered to the Iranian Registry of Clinical Trials (IRCT) with the approval number IRCT20220104053626N2 on the date of 13/02/2022.
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The right bug in the right place: opportunities for bacterial vaginosis treatment.
Wu, S, Hugerth, LW, Schuppe-Koistinen, I, Du, J
NPJ biofilms and microbiomes. 2022;8(1):34
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The vaginal microbiome is generally dominated by Lactobacilli bacteria. However, variations exist, and in some ethnic groups a dominance of non-Lactobacilli species is more common. Lactobacilli produce various antimicrobial substances which keep growth of other bacteria in check. Bacterial vaginosis (BV) is characterized by a disturbance of the vaginal microbe balance and deficiency of Lactobacilli, giving rise to the overgrowth of certain bacteria, such as Gardnerella, Atopobium, Megasphaera, Prevotella, and Sneathia. In some countries, BV can affect over half of the women. This review discusses the advantages and challenges of the current treatment options for BV and postulates directions for future research. The article examines the use of antibiotics, their effectiveness and difficulties in obtaining long-term remission, their negative impact on the existing vaginal microbiome, the risk of antibiotic resistance and the benefits and challenges of local antibiotic applications. Following this, the authors discussed the use of prebiotics and probiotics, possible reasons why clinical trials in the past showed mixed results, and what strains may be of particular importance in vaginal health, with L. crispatus and L. iners being of particular interest here. Considered are also factors that influence and enhance bacterial colonization. Lastly, the article summarizes some current thinking on Vaginal Microbiome Transplantation, which is the transfer of vaginal microbes and fluids from a healthy donor, what benefits they may have, the associated safety risks and legislative challenges. This review is a comprehensive summary of BV treatment options, their current evidence, efficacy and drawbacks, yielding useful information to consider in the clinical management of BV.
Abstract
Bacterial vaginosis (BV) is a condition in which the vaginal microbiome presents an overgrowth of obligate and facultative anaerobes, which disturbs the vaginal microbiome balance. BV is a common and recurring vaginal infection among women of reproductive age and is associated with adverse health outcomes and a decreased quality of life. The current recommended first-line treatment for BV is antibiotics, despite the high recurrence rate. Live biopharmaceutical products/probiotics and vaginal microbiome transplantation (VMT) have also been tested in clinical trials for BV. In this review, we discuss the advantages and challenges of current BV treatments and interventions. Furthermore, we provide our understanding of why current clinical trials with probiotics have had mixed results, which is mainly due to not administering the correct bacteria to the correct body site. Here, we propose a great opportunity for large clinical trials with probiotic strains isolated from the vaginal tract (e.g., Lactobacillus crispatus) and administered directly into the vagina after pretreatment.
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Probiotic treatment with specific lactobacilli does not improve an unfavorable vaginal microbiota prior to fertility treatment-A randomized, double-blinded, placebo-controlled trial.
Jepsen, IE, Saxtorph, MH, Englund, ALM, Petersen, KB, Wissing, MLM, Hviid, TVF, Macklon, N
Frontiers in endocrinology. 2022;13:1057022
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Efforts to improve pregnancy rates remain largely focused on enhancing the quality of the transferred embryo. However, there is increasing awareness of the potential role of the intra-uterine environment as a determinant for success. The aim of this study was to determine if lactobacilli-loaded vaginal capsules are superior to placebo in improving a vaginal microbiota reported as unfavourable to implantation in women scheduled for fertility treatment. This study is a single-centre, two-arm, double-blinded, randomised controlled study. The study enrolled women aged 18–40 years who were referred to the Fertility Clinic and whose vaginal microbiota prior to fertility treatment had been diagnosed as an unfavourable. Participants (n=77) were randomised in a 1:1 ratio to either lactobacilli-loaded vaginal capsules or placebo. Results did not show any significant effect of treatment with lactobacilli-loaded vaginal capsules on the unfavourable vaginal microbiota profile among women referred to fertility treatment. However, the study showed the highly dynamic nature of the vaginal microbiota, with a spontaneous improvement rate of 34.2% (of the patients) one to three months after the baseline sample. Authors conclude that probiotics use for the improvement of vaginal microbiota should be tempered with some caution. More studies of both the vaginal and endometrial microbiota are required to confirm the efficacy of specific vaginal probiotics before they can be considered as a therapeutic solution.
Abstract
OBJECTIVE To investigate whether treatment with proprietary lactobacilli-loaded vaginal capsules improves an unfavorable vaginal microbiome diagnosed using a commercially available test and algorithm. DESIGN A randomized, double-blinded, placebo-controlled study was conducted in 74 women prior to undergoing fertility treatment at a single university fertility clinic between April 2019 and February 2021. The women were randomly assigned in a 1:1 ratio to receive one vaginal capsule per day for 10 days containing either a culture of more than 108 CFU of Lactobacillus gasseri and more than 108 CFU Lactobacillus rhamnosus (lactobacilli group) or no active ingredient (placebo group). Vaginal swabs for microbiota analysis were taken at enrollment, after treatment and in the cycle following treatment. PARTICIPANTS AND METHODS Women aged 18-40 years who prior to fertility treatment were diagnosed with an unfavorable vaginal microbiota, characterized by either a low relative load of Lactobacillus or a high proportion of disrupting bacteria using the criteria of the IS-pro™ diagnostic system (ARTPred, Amsterdam, the Netherlands), were enrolled in the study. The primary outcome measure was the proportion of women with improvement of the vaginal microbiota after intervention. RESULTS The vaginal microbiota improved after intervention in 34.2% of all participants (lactobacilli group 28.9%, placebo group 40.0%), with no significant difference in the improvement rate between the lactobacilli and placebo groups, RR = 0.72 (95% CI 0.38-1.38). CONCLUSION This study indicates that administering vaginal probiotics may not be an effective means of modulating the vaginal microbiome for clinical purposes in an infertile population. However, a spontaneous improvement rate of 34.2% over a period of one to three months, confirming the dynamic nature of the vaginal microbiota, indicates that a strategy of postponing further IVF treatment to await microbiota improvement may be relevant in some patients, but further research is needed. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov, identifier NCT03843112.
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Disturbances of Vaginal Microbiome Composition in Human Papillomavirus Infection and Cervical Carcinogenesis: A Qualitative Systematic Review.
Wu, M, Li, H, Yu, H, Yan, Y, Wang, C, Teng, F, Fan, A, Xue, F
Frontiers in oncology. 2022;12:941741
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Cervical cancer remains the fourth most prevalent cancer in women worldwide. The infection of certain strains of human papillomavirus (HPV)) are thought to have an important causative role in the development of cervical cancer. But since a vast majority of HPV infections clear naturally within a few months, this indicates other factors at play determine the progression of the disease and its cancerous developments. Recent findings indicate that there may be a close link between disruptions of the vaginal microbiome and HPV infection, cervical lesions, cervical cancer and other gynaecological diseases. However, the evidence thus far is quite varied. Hence this systematic review sought to gather the current evidence and integrate it to create up-to-date knowledge. Included were the 22 studies relating to vaginal microbiota, and women with HPV-associated cervical diseases. The studies were conducted in various countries around the world and contained a mixture of case-controlled, cross-sectional and longitudinal studies. The authors acknowledge the challenges of summarising the findings due to differences in how the studies have been conducted. The results of the review showed that vaginal disturbances in HPV infections and related cervical diseases, seem to manifest in decreases in Lactobacilli, and increases in aerobic and anaerobic bacteria. Lactobacillus iners seemed to have either protective or pathogenic effects. They also noted that there are geographical and ethnic differences and patterns, which made the consolidation of results more challenging. For future research, the authors deemed the role of the Lactobacillus family of particular interest.
Abstract
BACKGROUND Emerging evidence has demonstrated a close association between perturbations in vaginal microbiota composition in women and human papillomavirus (HPV) infection, cervical lesions, and cervical cancer (Ca); however, these findings are highly heterogeneous and inconclusive. AIM: To perform a comprehensive systematic review of the global disturbance in the vaginal microbiota, specifically in women with HPV-associated cervical diseases, and to further conduct within- and across-disease comparisons. METHOD Twenty-two records were identified in a systematic literature search of PubMed, Web of Science, and Embase up to February 28, 2022. We extracted microbial changes at the community (alpha and beta diversity) and taxonomic (relative abundance) levels. Within- and across-disease findings on the relative abundance of taxonomic assignments were qualitatively synthesized. RESULTS Generally, significantly higher alpha diversity was observed for HPV infection, cervical lesions, and/or cancer patients than in controls, and significant differences within beta diversity were observed for the overall microbial composition across samples. In within-disease comparisons, the genera Gardnerella, Megasphaera, Prevotella, Peptostreptococcus, and Streptococcus showed the greatest abundances with HPV infection; Sneathia and Atopobium showed inconsistent abundance with HPV infection, and Staphylococcus was observed in Ca. Across diseases, we find increased levels of Streptococcus and varying levels of Gardnerella were shared across HPV infections, high-grade squamous intraepithelial lesions, and Ca, whereas Lactobacillus iners varied depending on the HPV-related disease subtype. CONCLUSIONS This systematic review reports that vaginal microbiome disturbances are correlated to the depletion of Lactobacillus, enrichment of anaerobes, and increased abundance of aerobic bacteria in HPV infection and related cervical diseases. Moreover, L. iners may exert either protective or pathogenic effects on different HPV-related diseases.
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Gut and Reproductive Tract Microbiota Adaptation during Pregnancy: New Insights for Pregnancy-Related Complications and Therapy.
Siena, M, Laterza, L, Matteo, MV, Mignini, I, Schepis, T, Rizzatti, G, Ianiro, G, Rinninella, E, Cintoni, M, Gasbarrini, A
Microorganisms. 2021;9(3)
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During pregnancy, several adaptations occur in the female organism. In fact, from fertilization until delivery, the maternal body changes and activates a series of physiological transformations to welcome the new life. The microbiota as a component of human bodies is subject to these modifications. This study is a review that focused on gut and reproductive tract microbiota variations during physiologic pregnancy and in case of pregnancy complications, particularly gestational diabetes mellitus (GDM), pre-eclampsia (PE), and preterm birth (PTB). Results show that: - during pregnancy, major changes have been seen in mothers’ gut microbiota. Between the first and third trimester of pregnancy, to support the foetus growth, there is a shift towards communities of microbes implicated in energy production and storage. - in nonpregnant women, vaginal microbiota could be classified into five major types, representing the community state types. - meconium’s microbes seems to be dominated by the Enterobacteriaceae family, suggesting prenatally stepwise colonization. - gut microbiota may contribute to enhanced insulin resistance in early pregnancy (1st and 2nd trimester). - microbiota imbalances in PE women are related not only with blood pressure levels but also with markers of kidney dysfunction. Thus, it is of key importance to understand the role of microbiota and other factors involved in the etiopathogenesis of PE - dysbiosis is related to PTB (however, further studies are necessary to better understand the correlation between this pregnancy complication and the specific microbiota alteration). Authors conclude that microbiota modulation could be a novel strategy to reduce the morbidity and mortality related to pregnancy complications in the future.
Abstract
Pregnancy is characterized by maternal adaptations that are necessary to create a welcoming and hospitable environment for the fetus. Studies have highlighted how the microbiota modulates several networks in humans through complex molecular interactions and how dysbiosis (defined as quantitative and qualitative alterations of the microbiota communities) is related to human pathologies including gynecological diseases. This review analyzed how maternal uterine, vaginal, and gut microbiomes could impact on fetus health during the gestational period. We evaluated the role of a dysbiotic microbiota in preterm birth, chorioamnionitis, gestational diabetes mellitus and pre-eclampsia. For many years it has been hypothesized that newborns were sterile organisms but in the past few years this paradigm has been questioned through the demonstration of the presence of microbes in the placenta and meconium. In the future, we should go deeper into the concept of in utero colonization to better understand the role of microbiota through the phases of pregnancy. Numerous studies in the literature have already showed interesting results regarding the role of microbiota in pregnancy. This evidence gives us the hope that microbiota modulation could be a novel strategy to reduce the morbidity and mortality related to pregnancy complications in the future.
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Vaginal and Anal Microbiome during Chlamydia trachomatis Infections.
Raimondi, S, Candeliere, F, Amaretti, A, Foschi, C, Morselli, S, Gaspari, V, Rossi, M, Marangoni, A
Pathogens (Basel, Switzerland). 2021;10(10)
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Chlamydia trachomatis (CT) is the agent of the most common bacterial sexually transmitted infection (STI) worldwide. This study is a cohort study. The composition of vaginal and anal microbiome in a cohort of sexually active young women was investigated comparing the bacterial composition of CT-infected women (n = 10) to a negative control group (n = 16). Results showed that: - both vaginal and anal ecosystems were characterised by a degree of dysbiosis in case of CT infection, with several changes in the microbial composition compared to CT-negative women. - bacteria dominance was different for patients with anal CT infection (Parvimonas and Pseudomonas), than those of CT-negative women (Escherichia and Enterococcus). - there were significant differences in several functional pathways between CT-positive patients and the control group. Among all, a higher involvement of chorismate and aromatic amino acid biosynthesis, as well as an increase in mixed acid fermentation, were predicted at the vaginal level of CT-positive patients. Authors conclude that their findings could be useful to set up new diagnostic/prognostic tools, to find correlations with the presence of peculiar clinical or behavioural traits, and to evaluate the possibility of a different susceptibility to chlamydial STIs based on microbiome composition.
Abstract
Background.Chlamydia trachomatis (CT) is the agent of the most common bacterial sexually transmitted infection worldwide, with a significant impact on women's health. Despite the increasing number of studies about the vaginal microbiome in women with CT infections, information about the composition of the anal microbiome is still lacking. Here, we assessed the bacterial community profiles of vaginal and anal ecosystems associated or not with CT infection in a cohort of Caucasian young women. Methods. A total of 26 women, including 10 with a contemporary vaginal and ano-rectal CT infection, were enrolled. Composition of vaginal and anal microbiome was studied by 16S rRNA gene profiling. Co-occurrence networks of bacterial communities and metagenome metabolic functions were determined. Results. In case of CT infection, both vaginal and anal environments were characterized by a degree of dysbiosis. Indeed, the vaginal microbiome of CT-positive women were depleted in lactobacilli, with a significant increase in dysbiosis-associated bacteria (e.g., Sneathia, Parvimonas, Megasphaera), whereas the anal microbiota of CT-infected women was characterized by higher levels of Parvimonas and Pseudomonas and lower levels of Escherichia. Interestingly, the microbiome of anus and vagina had numerous bacterial taxa in common, reflecting a significant microbial 'sharing' between the two sites. In the vaginal environment, CT positively correlated with Ezakiella spp. while Gardnerella vaginalis co-occurred with several dysbiosis-related microbes, regardless of CT vaginal infection. The vaginal microbiome of CT-positive females exhibited a higher involvement of chorismate and aromatic amino acid biosynthesis, as well as an increase in mixed acid fermentation. Conclusions. These data could be useful to set up new diagnostic/prognostic tools, offering new perspectives for the control of chlamydial infections.
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Group B Streptococcus and the vaginal microbiome among pregnant women: a systematic review.
Lim, S, Rajagopal, S, Jeong, YR, Nzegwu, D, Wright, ML
PeerJ. 2021;9:e11437
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Variations within the vaginal microbiome have been associated with higher risk for preterm birth and other pregnancy complications. For example, there is a notable lack of discussion of S. agalactiae, commonly referred to as Group B Streptococcus (GBS), a known pathogen associated with poor maternal, foetal, and neonatal outcomes in amplicon-based metagenomic vaginal microbiome studies during pregnancy. The main aim of this study was to determine how often GBS is reported in studies of the vaginal microbiome during pregnancy. This study is a systematic review of forty-five studies. Out of the forty-five studies, 13 (28.9%) reported GBS. Results show that no systematic differences in factors previously known to introduce bias in microbiome studies were associated with the lack of GBS reporting. However, there was considerable heterogeneity in research methods employed across studies. Authors conclude that future studies evaluating the presence of GBS may need to adopt both confirmatory testing for GBS via culture and parallel comparison with results obtained from metagenomic/meta-taxonomic approaches.
Abstract
BACKGROUND Vaginal microbiome studies frequently report diversity metrics and communities of microbiomes associated with reproductive health outcomes. Reports of Streptococcus agalactiae (also known as Group B Streptococcus or GBS), the leading cause of neonatal infectious morbidity and mortality, are notably lacking from the studies of the vaginal microbiome, despite being a known contributor to preterm birth and other complications. Therefore, the purpose of this systematic review was to explore the frequency of GBS reporting in vaginal microbiome literature pertaining to pregnancy and to examine methodological bias that contributes to differences in species and genus-level microbiome reporting. Lack of identification of GBS via sequencing-based approaches due to methodologic or reporting bias may result incomplete understanding of bacterial composition during pregnancy and subsequent birth outcomes. METHODOLOGY A systematic review was conducted following the PRISMA guideline. Three databases (PubMed, CINAHL, and Web of Science) were used to identify papers for review based on the search terms "vaginal microbiome", "pregnancy", and "16S rRNA sequencing". Articles were evaluated for methods of DNA extraction and sequencing, 16S region, taxonomy classification database, number of participants or vaginal specimens, and pregnancy trimester. RESULTS Forty-five research articles reported employing a metagenomic approach or 16S approach for vaginal microbiome analysis during pregnancy that explicitly reported taxonomic composition and were included in this review. Less than 30% of articles reported the presence of GBS (N = 13). No significant differences in methodology were identified between articles that reported versus did not report GBS. However, there was large variability across research methods used for vaginal microbiome analysis and species-level bacterial community reporting. CONCLUSION Considerable differences in study design and data formatting methods may contribute to underrepresentation of GBS, and other known pathogens, in existing vaginal microbiome literature. Previous studies have identified considerable variation in methodology across vaginal microbiome studies. This study adds to this body of work because in addition to laboratory or statistical methods, how results and data are shared (e.g., only analyzing genus level data or 20 most abundant microbes), may hinder reproducibility and limit our understanding of the influence of less abundant microbes. Sharing detailed methods, analysis code, and raw data may improve reproducibility and ability to more accurately compare microbial communities across studies.