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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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Contribution of Lactobacillus iners to Vaginal Health and Diseases: A Systematic Review.
Zheng, N, Guo, R, Wang, J, Zhou, W, Ling, Z
Frontiers in cellular and infection microbiology. 2021;11:792787
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The vaginal microbiome is an important contributor to vaginal health. Here the dominance of Lactobacilli species, alongside their antimicrobial compounds play a critical role in contributing and protecting the vaginal milieu. Conversely the disruption or absence of Lactobacilli dominance is frequently associated with vaginal disease and infections. One of the Lactobacilli species prevalent in the vaginal microbiome is Lactobacillus iners. It was long overlooked in research due to it being so difficult to culture, and it was first identified in 1999 thanks to DNA sequencing. Researchers since discovered that the relationship between L. iners and vaginal health is far more complicated and ambiguous compared to the other Lactobacilli species. This systematic review explores the current knowledge of the characteristics of L. iners and its role in vaginal health and disease. The article discusses L. iners identification, genetic make up and differences to other Lactobacilli species and how they relate to vaginal health. The article also summarizes L. iners nutrient requirements and its role in diseases like dysbiosis, bacterial vaginosis, sexually transmitted infections and biofilm formation. Furthermore the authors look at the relation between L. iners and premature birthing, fertility and menstrual cycles. A final section in discusses the antimicrobial and immune sytem activating qualities of L. iners. In light of all these findings the authors describe L . iners as a very unique Lactobacilli due to its unusual characteristics. Whether L. iners is beneficial or pathogenic for the host remains controversial, as it can adapt to high and low pH environment and is seen in health and equally dysbiotic states of infection. Hence some describe it as a transitional species that colonizes the vagina after disturbances. It may be a risk factor for infections by contributing to the onset and maintenance of dysbiotic disturbances. Further studies are needed to clarify the role of L. iners and its role on vaginal health and whether it could serve as a biomarker for vaginal inflammation. This article is a useful summary about the characteristics and role of L. iners in vaginal health in disease.
Abstract
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.
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Longitudinal Study of the Psoriasis-Associated Skin Microbiome during Therapy with Ustekinumab in a Randomized Phase 3b Clinical Trial.
Loesche, MA, Farahi, K, Capone, K, Fakharzadeh, S, Blauvelt, A, Duffin, KC, DePrimo, SE, Muñoz-Elías, EJ, Brodmerkel, C, Dasgupta, B, et al
The Journal of investigative dermatology. 2018;138(9):1973-1981
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Chronic plaque psoriasis is an immune-mediated disease of the skin and joints. A growing appreciation of the role of the innate immune system in psoriasis pathogenesis stems from the prominent role of inflammatory cytokines and cells associated with innate immunity in the disease and associations observed between psoriasis and genetic variations involved in innate immunity. The aim of this study was to assess changes of the skin microbiome in the setting of a longitudinal phase 3b study of patients receiving up to 2 years of ustekinumab therapy. Results show that prior to treatment, there were minor, body-site specific differences in microbial diversity and composition when comparing lesional with non-lesional skin. Microbial heterogeneity was greater in lesional skin than non-lesional skin. During ustekinumab treatment, the composition of microbiota diverged further between lesional and non-lesional skin across body sites. The divergence observed between lesional and non-lesional skin during ustekinumab treatment varied by body site. Authors conclude that their findings may help inform future study design and it may also have medically relevant implications for diagnostics and therapeutics involving the skin microbiome.
Abstract
Plaque psoriasis, a chronic inflammatory disease primarily affecting the skin, is thought to have a multifactorial etiology, including innate immune system dysregulation, environmental triggers, and genetic susceptibility. We sought to further understand the role of skin microbiota in psoriasis pathogenesis, as well as their response to therapy. We systematically analyzed dynamic microbiota colonizing psoriasis lesions and adjacent nonlesional skin in 114 patients prior to and during ustekinumab treatment in a phase 3b clinical trial. By sequencing the bacterial 16S ribosomal RNA gene from skin swab samples obtained at six anatomical sites, we identified minor, site-specific differences in microbial diversity and composition between pretreatment lesional and nonlesional skin. During therapy, microbial communities within lesional and nonlesional skin diverged, and body-site dispersion increased, reflecting microbial skin site-specificity. Microbiota demonstrated greater pretreatment heterogeneity in psoriatic lesions than in nonlesional skin, and variance increased as treatment progressed. Microbiota colonizing recurrent lesions did not overlap with pretreatment lesional microbiota, suggesting colonization patterns varied between initial and recurrent psoriatic lesions. While plaque psoriasis does not appear to be associated with specific microbes and/or microbial diversity, this large dataset provides insight into microbial variation associated with (i) disease in different body locations, (ii) initial versus recurrent lesions, and (iii) anti-IL12/23 therapy.
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Bacteriophage transfer during faecal microbiota transplantation in Clostridium difficile infection is associated with treatment outcome.
Zuo, T, Wong, SH, Lam, K, Lui, R, Cheung, K, Tang, W, Ching, JYL, Chan, PKS, Chan, MCW, Wu, JCY, et al
Gut. 2018;67(4):634-643
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The microbiome and its effects on health have received plenty of attention and research. A lot less is known about the virome, the collection of viruses in and on our bodies. This pilot observational study looked at the connection between the viruses and bacteria in the guts of patients with Clostridium difficile infection (CDI), compared to healthy controls, and changes and treatment outcomes observed after faecal microbiota transplantation (FMT) compared to vancomycin treatment. The study showed that, compared to healthy household controls, people with CDI had significant viral dysbiosis, in particular higher abundance but lower diversity, richness and evenness of the bacteriophage (a virus that infects bacteria) Caudovirales, the most abundant intestinal bacteriophage in humans. FMT changed both, the composition of the microbiome as well as the virome, whilst antibiotic treatment did not affect the bacteriophage composition. Treatment outcome with FMT depended on changes in Caudivirales. Although a small pilot study, according to the authors, this is the biggest study into the importance of intestinal viruses, and their correlation with the microbiome, in disease and for treatment outcomes. The authors point out that, as this was an observational study, it is not possible to ascertain whether the altered virome is a cause or a consequence of the disease.
Abstract
OBJECTIVE Faecal microbiota transplantation (FMT) is effective for the treatment of recurrent Clostridium difficile infection (CDI). Studies have shown bacterial colonisation after FMT, but data on viral alterations in CDI are scarce. We investigated enteric virome alterations in CDI and the association between viral transfer and clinical outcome in patients with CDI. DESIGN Ultra-deep metagenomic sequencing of virus-like particle preparations and bacterial 16S rRNA sequencing were performed on stool samples from 24 subjects with CDI and 20 healthy controls. We longitudinally assessed the virome and bacterial microbiome changes in nine CDI subjects treated with FMT and five treated with vancomycin. Enteric virome alterations were assessed in association with treatment response. RESULTS Subjects with CDI demonstrated a significantly higher abundance of bacteriophage Caudovirales and a lower Caudovirales diversity, richness and evenness compared with healthy household controls. Significant correlations were observed between bacterial families Proteobacteria, Actinobacteria and Caudovirales taxa in CDI. FMT treatment resulted in a significant decrease in the abundance of Caudovirales in CDI. Cure after FMT was observed when donor-derived Caudovirales contigs occupied a larger fraction of the enteric virome in the recipients (p=0.024). In treatment responders, FMT was associated with alterations in the virome and the bacterial microbiome, while vancomycin treatment led to alterations in the bacterial community alone. CONCLUSIONS In a preliminary study, CDI is characterised by enteric virome dysbiosis. Treatment response in FMT was associated with a high colonisation level of donor-derived Caudovirales taxa in the recipient. Caudovirales bacteriophages may play a role in the efficacy of FMT in CDI. TRIAL REGISTRATION NUMBER NCT02570477.
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Mucosal microbiome dysbiosis in gastric carcinogenesis.
Coker, OO, Dai, Z, Nie, Y, Zhao, G, Cao, L, Nakatsu, G, Wu, WK, Wong, SH, Chen, Z, Sung, JJY, et al
Gut. 2018;67(6):1024-1032
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Gastric cancer (GC) is the 4th most common cancer and a leading cause of cancer-related deaths worldwide. Infection with Helicobacter pylori is an important risk factor for GC and other changes in gastric microbial composition are thought to play role in gastric carcinogenesis. This observational study aimed to elucidate the microbial changes that are characteristic for the different stages of gastric tumor development. The authors found significant changes in microbial composition in stomach cancer patients compared to patients with pre-cancerous mucosal changes, with an increase of some and a depletion of other bacteria, in particular an increase in oral bacteria, which is also found in other gastrointestinal cancers. They also found that interactions between the depleted and enriched bacterial species progressively increased with progressing carcinogenesis. Whilst there was no difference in the diversity of bacteria between H. pylori-positive and negative samples, more bacterial interactions were observed in H. pylori-negative samples. The authors conclude that significant gastric dysbiosis can be seen in samples of stomach cancer patients, however, they point out that from their study it is impossible to tell whether the bacteria increased in GC are “drivers” or “passengers” of gastric carcinogenesis. Their call for more research focusses on using this knowledge to develop better diagnostic biomarkers, rather than using this information for prevention or treatment of stomach cancer.
Abstract
OBJECTIVES We aimed to characterise the microbial changes associated with histological stages of gastric tumourigenesis. DESIGN We performed 16S rRNA gene analysis of gastric mucosal samples from 81 cases including superficial gastritis (SG), atrophic gastritis (AG), intestinal metaplasia (IM) and gastric cancer (GC) from Xi'an, China, to determine mucosal microbiome dysbiosis across stages of GC. We validated the results in mucosal samples of 126 cases from Inner Mongolia, China. RESULTS We observed significant mucosa microbial dysbiosis in IM and GC subjects, with significant enrichment of 21 and depletion of 10 bacterial taxa in GC compared with SG (q<0.05). Microbial network analysis showed increasing correlation strengths among them with disease progression (p<0.001). Five GC-enriched bacterial taxa whose species identifications correspond to Peptostreptococcus stomatis, Streptococcus anginosus, Parvimonas micra, Slackia exigua and Dialister pneumosintes had significant centralities in the GC ecological network (p<0.05) and classified GC from SG with an area under the receiver-operating curve (AUC) of 0.82. Moreover, stronger interactions among gastric microbes were observed in Helicobacter pylori-negative samples compared with H. pylori-positive samples in SG and IM. The fold changes of selected bacteria, and strengths of their interactions were successfully validated in the Inner Mongolian cohort, in which the five bacterial markers distinguished GC from SG with an AUC of 0.81. CONCLUSIONS In addition to microbial compositional changes, we identified differences in bacterial interactions across stages of gastric carcinogenesis. The significant enrichments and network centralities suggest potentially important roles of P. stomatis, D. pneumosintes, S. exigua, P. micra and S. anginosus in GC progression.
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Increased richness and diversity of the vaginal microbiota and spontaneous preterm birth.
Freitas, AC, Bocking, A, Hill, JE, Money, DM
Microbiome. 2018;6(1):117
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The bacterial community in the female lower genital tract plays an important role in the health of both mother and baby. Imbalances in the vaginal microbiota have been associated with negative reproductive outcomes, such as premature birth. Bacterial infection is thought to be an important contributor to the onset of premature labour. The objective of this study was to compare the vaginal microbiota of pregnant women who had premature births (<37 weeks) with those of pregnant women who delivered at term. Vaginal swabs were collected from 216 Canadian women at 11-16 weeks of gestational age. Of these, 170 pregnancies went to full term, and 46 women had premature births. The vaginal microbiota of women who experienced premature birth had higher richness and diversity and higher Mollicutes prevalence when compared to those of women who delivered at term. The results confirm previous reports of an association between Mollicutes and premature birth and suggest that a more diverse microbiome may contribute to the microbiome’s role in premature births.
Abstract
BACKGROUND The bacterial community present in the female lower genital tract plays an important role in maternal and neonatal health. Imbalances in this microbiota have been associated with negative reproductive outcomes, such as spontaneous preterm birth (sPTB), but the mechanisms underlying the association between a disturbed microbiota and sPTB remain poorly understood. An intrauterine infection ascending from the vagina is thought to be an important contributor to the onset of preterm labour. Our objective was to characterize the vaginal microbiota of pregnant women who had sPTB (n = 46) and compare to those of pregnant women who delivered at term (n = 170). Vaginal swabs were collected from women at 11-16 weeks of gestational age. Microbiota profiles were created by PCR amplification and pyrosequencing of the cpn60 universal target region. RESULTS Profiles clustered into seven community state types: I (Lactobacillus crispatus dominated), II (Lactobacillus gasseri dominated), III (Lactobacillus iners dominated), IVA (Gardnerella vaginalis subgroup B or mix of species), IVC (G. vaginalis subgroup A dominated), IVD (G. vaginalis subgroup C dominated) and V (Lactobacillus jensenii dominated). The microbiota of women who experienced preterm birth (< 37 weeks gestation) had higher richness and diversity and higher Mollicutes prevalence when compared to those of women who delivered at term. The two groups did not cluster according to CST, likely because CST assignment is driven in most cases by the dominance of one particular species, overwhelming the contributions of more rare taxa. In conclusion, we did not identify a specific microbial community structure that predicts sPTB, but differences in microbiota richness, diversity and Mollicutes prevalence were observed between groups. CONCLUSIONS Although a causal relationship remains to be determined, our results confirm previous reports of an association between Mollicutes and sPTB and further suggest that a more diverse microbiome may be important in the pathogenesis of some cases.
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Vaginal dysbiosis increases risk of preterm fetal membrane rupture, neonatal sepsis and is exacerbated by erythromycin.
Brown, RG, Marchesi, JR, Lee, YS, Smith, A, Lehne, B, Kindinger, LM, Terzidou, V, Holmes, E, Nicholson, JK, Bennett, PR, et al
BMC medicine. 2018;16(1):9
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Preterm premature rupture of the membranes (PPROM) is a pregnancy complication in which the amniotic sac ruptures before week 37 of the pregnancy, leading to an increased risk of infection and premature birth. Women who experience PPROM are usually given antibiotics to help prevent infections which, left untreated, could endanger their babies’ lives. It is thought that disturbances in the mum’s vaginal bacteria may be related to the risk of PPROM. In this study, researchers examined the vaginal bacteria of women with PPROM, before and after antibiotic treatment. A total of 250 pregnant women who had been identified as at risk of a premature birth were included in the study. Disturbance of the normal vaginal bacteria, characterised by low levels of Lactobacillus, was present in a third of women who went on to develop PPROM. This disturbance of the normal vaginal bacteria was made worse by antibiotic treatment particularly in women initially colonised by Lactobacillus spp. Lower levels of Lactobacillus and increased abundance of Sneathia spp. were associated with an increased likelihood of funisitis (inflammation of the umbilical cord) and sepsis in the newborn. The authors concluded that the composition of the vaginal microbiota is a risk factor for PPROM and is associated with unfavourable short-term outcomes for the mother and newborn. This highlights vaginal microbiota as a potentially modifiable risk factor for PPROM and they suggest that the routine use of antibiotics such as erythromycin for PPROM should be re-examined.
Abstract
BACKGROUND Preterm prelabour rupture of the fetal membranes (PPROM) precedes 30% of preterm births and is a risk factor for early onset neonatal sepsis. As PPROM is strongly associated with ascending vaginal infection, prophylactic antibiotics are widely used. The evolution of vaginal microbiota compositions associated with PPROM and the impact of antibiotics on bacterial compositions are unknown. METHODS We prospectively assessed vaginal microbiota prior to and following PPROM using MiSeq-based sequencing of 16S rRNA gene amplicons and examined the impact of erythromycin prophylaxis on bacterial load and community structures. RESULTS In contrast to pregnancies delivering at term, vaginal dysbiosis characterised by Lactobacillus spp. depletion was present prior to the rupture of fetal membranes in approximately a third of cases (0% vs. 27%, P = 0.026) and persisted following membrane rupture (31%, P = 0.005). Vaginal dysbiosis was exacerbated by erythromycin treatment (47%, P = 0.00009) particularly in women initially colonised by Lactobacillus spp. Lactobacillus depletion and increased relative abundance of Sneathia spp. were associated with subsequent funisitis and early onset neonatal sepsis. CONCLUSIONS Our data show that vaginal microbiota composition is a risk factor for subsequent PPROM and is associated with adverse short-term maternal and neonatal outcomes. This highlights vaginal microbiota as a potentially modifiable antenatal risk factor for PPROM and suggests that routine use of erythromycin for PPROM be re-examined.
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Acceptability of a very-low-energy diet in Type 2 diabetes: patient experiences and behaviour regulation.
Rehackova, L, Araújo-Soares, V, Adamson, AJ, Steven, S, Taylor, R, Sniehotta, FF
Diabetic medicine : a journal of the British Diabetic Association. 2017;34(11):1554-1567
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Patients with type 2 diabetes can return to normal blood glucose levels through substantial weight loss. While many studies have addressed this, very few have assessed the effects of adherence to a very-low-energy diet (VLED) on patients’ quality of life. The aim of this study was to evaluate the experiences of adhering to VLED for patients in remission for type 2 diabetes. Fifteen participants were interviewed before and after the 8-week VLED intervention and narratives were analysed. This study identified common barriers, facilitators and strategies used by the participants. Overall, participants found adherence easier than anticipated, and found barriers to be offset by suggested behaviour-regulation strategies. Based on this study, the authors conclude dietary treatment for reversal of type 2 diabetes is acceptable and feasible in motivated patients, and suggest further controlled research be done to confirm the validity and applicability of these findings.
Abstract
AIMS: To evaluate the acceptability of an 8-week very-low-energy diet for remission of Type 2 diabetes, and to identify barriers and facilitators of adherence and behaviour-regulation strategies used by participants in the Counterbalance study. METHODS Eighteen of 30 participants in the Counterbalance study (ISRCTN88634530) took part in semi-structured interviews. Of these, 15 participants were interviewed before and after the 8-week very-low-energy diet intervention. Thematic analysis was used to analyse the narratives. RESULTS The prospect of diabetes remission, considerable weight loss, and long-term health improvement provided participants with substantial initial motivation. This motivation was sustained through the experience of rapid weight loss, improvements in blood glucose levels, social support and increased physical and psychological well-being. Overall, adherence to the very-low-energy diet for 8 weeks was perceived as much easier than anticipated, but required personal effort. Participants addressed challenges by removing food from the environment, planning, avoidance of tempting situations or places, and self-distraction. Weight loss and improvements in blood glucose levels lead to a sense of achievement and improvements in physical and psychological wellbeing. CONCLUSIONS Dietary treatment for reversal of Type 2 diabetes is acceptable and feasible in motivated participants, and the process is perceived as highly gratifying. Research outside of controlled trial settings is needed to gauge the generalisability of these findings.