Immunoglobulin A response against Gardnerella vaginalis hemolysin and sialidase activity in bacterial vaginosis

The role of sialidases in the pathogenesis of bacterial vaginosis and their use as a promising pharmacological target in bacterial vaginosis

Bacterial vaginosis (BV) is an infection of the genital tract characterized by disturbance of the normally Lactobacilli-dominated vaginal flora due to the overgrowth of Gardnerella and other anaerobic bacteria. Gardnerella vaginalis, an anaerobic pathogen and the major pathogen of BV, produces sialidases that cleave terminal sialic acid residues off of human glycans. By desialylation, sialidases not only alter the function of sialic acid-containing glycoconjugates but also play a vital role in the attachment, colonization and spread of many other vaginal pathogens. With known pathogenic effects, excellent performance of sialidase-based diagnostic tests, and promising therapeutic potentials of sialidase inhibitors, sialidases could be used as a biomarker of BV. This review explores the sources of sialidases and their role in vaginal dysbiosis, in aims to better understand their participation in the pathogenesis of BV and their value in the diagnosis and treatment of BV.

Mechanistic Insights into Immune Suppression and Evasion in Bacterial Vaginosis

The immunological response to bacterial vaginosis (BV) remains poorly understood and recurrent BV is still a major public health burden especially in the pregnant population. This article reviews the potential mechanisms by which BV-associated bacteria suppress and circumvent the host and microbial defence responses, and propagate their survival/dominance without overt inflammation. We discuss the composition of cervicovaginal mucosal barrier and the mechanism by which BV circumvents host defence: the degradation of the mucosal barrier and immunoglobulin A (IgA); the BV-associated organism Gardnerella vaginalis haemolysin (vaginolysin); diminished IgA response against vaginolysin; mucosal sialic acid degradation, foraging and depletion; inhibition of IL-8-induced neutrophilic infiltration; and metabolite-induced incapacitation of neutrophil and monocyte chemotaxis. We also highlight the tolerance/resistance to both host and antimicrobial molecules mounted by BV-associated biofilms. A plausible role of sialic acid-binding immunoglobulin-like lectins (SIGLECS) was also suggested. Sialidase, which is often produced by G. vaginalis, is central to the immunosuppression, relapse and recurrence observed in BV, although it is supported by other hydrolytic enzymes, vaginolysin and immunomodulatory metabolites.

Enhanced IgA coating of bacteria in women with Lactobacillus crispatus-dominated vaginal microbiota

BACKGROUND

Immunoglobulin A (IgA) plays an important role in maintaining a healthy intestinal microbiome, but little is known about the interaction between local immunoglobulins and the vaginal microbiome. We assessed immunoglobulins (unbound and bound to bacteria), their association with vaginal microbiota composition and the changes over time in 25 healthy women of reproductive age.

RESULTS

In both Lactobacillus crispatus-dominated and non-L. crispatus-dominated microbiota, IgA and IgG (unbound and bound to bacteria) were higher during menses (T = 1) compared to day 7‑11 (T = 2) and day 17‑25 (T = 3) after menses onset. The majority of vaginal bacteria are coated with IgA and/or IgG. Women with L. crispatus-dominated microbiota have increased IgA coating of vaginal bacteria compared to women with other microbiota compositions, but contained less IgA per bacterium. Presence of a dominantly IgA-coated population at T = 2 and/or T = 3 was also strongly associated with L. crispatus-dominated microbiota. In women with non-L. crispatus-dominated microbiota, more bacteria were uncoated. Unbound IgA, unbound IgG, and bound IgG levels were not associated with microbiota composition.

CONCLUSIONS

In conclusion, L. crispatus-dominated vaginal microbiota have higher levels of bacterial IgA coating compared to non-L. crispatus-dominated vaginal microbiota. Similar to its regulating function in the intestinal tract, we hypothesize that IgA is involved in maintaining L. crispatus-dominated microbiota in the female genital tract. This may play a role in L. crispatus-associated health benefits. Video abstract.

Nugent Score, Amsel's Criteria, and a Point-of-Care Rapid Test for Diagnosis of Bacterial Vaginosis: Performance in a Cohort of Kenyan Women

ABSTRACT

There are minimal data on the BVBlue test for diagnosis of bacterial vaginosis (BV) in Africa. Among 701 Kenyan women, compared with Nugent score ≥7, the BVBlue test had moderate sensitivity (81.9%; 95% confidence interval, 76.5%-86.5%) and high specificity (92.4%; 95% confidence interval, 89.5%-94.6%). This test may provide a complimentary approach to syndromic management.

Large-scale characterisation of the pregnancy vaginal microbiome and sialidase activity in a low-risk Chinese population

Vaginal microbiota-host interactions are linked to preterm birth (PTB), which continues to be the primary cause of global childhood mortality. Due to population size, the majority of PTB occurs in Asia, yet there have been few studies of the pregnancy vaginal microbiota in Asian populations. Here, we characterized the vaginal microbiome of 2689 pregnant Chinese women using metataxonomics and in a subset (n = 819), the relationship between vaginal microbiota composition, sialidase activity and leukocyte presence and pregnancy outcomes. Vaginal microbiota were most frequently dominated by Lactobacillus crispatus or L. iners, with the latter associated with vaginal leukocyte presence. Women with high sialidase activity were enriched for bacterial vaginosis-associated genera including Gardnerella, Atopobium and Prevotella. Vaginal microbiota composition, high sialidase activity and/or leukocyte presence was not associated with PTB risk suggesting underlying differences in the vaginal microbiota and/or host immune responses of Chinese women, possibly accounting for low PTB rates in this population.

Bacterial vaginosis and health-associated bacteria modulate the immunometabolic landscape in 3D model of human cervix

Bacterial vaginosis (BV) is an enigmatic polymicrobial condition characterized by a depletion of health-associated Lactobacillus and an overgrowth of anaerobes. Importantly, BV is linked to adverse gynecologic and obstetric outcomes: an increased risk of sexually transmitted infections, preterm birth, and cancer. We hypothesized that members of the cervicovaginal microbiota distinctly contribute to immunometabolic changes in the human cervix, leading to these sequelae. Our 3D epithelial cell model that recapitulates the human cervical epithelium was infected with clinical isolates of cervicovaginal bacteria, alone or as a polymicrobial community. We used Lactobacillus crispatus as a representative health-associated commensal and four common BV-associated species: Gardnerella vaginalis, Prevotella bivia, Atopobium vaginae, and Sneathia amnii. The immunometabolic profiles of these microenvironments were analyzed using multiplex immunoassays and untargeted global metabolomics. A. vaginae and S. amnii exhibited the highest proinflammatory potential through induction of cytokines, iNOS, and oxidative stress-associated compounds. G. vaginalis, P. bivia, and S. amnii distinctly altered physicochemical barrier-related proteins and metabolites (mucins, sialic acid, polyamines), whereas L. crispatus produced an antimicrobial compound, phenyllactic acid. Alterations to the immunometabolic landscape correlate with symptoms and hallmarks of BV and connected BV with adverse women’s health outcomes. Overall, this study demonstrated that 3D cervical epithelial cell colonized with cervicovaginal microbiota faithfully reproduce the immunometabolic microenvironment previously observed in clinical studies and can successfully be used as a robust tool to evaluate host responses to commensal and pathogenic bacteria in the female reproductive tract.

Nanophotonic Sialidase Immunoassay for Bacterial Vaginosis Diagnosis

Bacterial vaginosis (BV) affects reproductive-age women and can lead to pelvic inflammatory disease, postpartum endometritis, and preterm labor/delivery and predisposes the infection of sexually transmitted diseases. Typically, BV diagnosis involves the analysis of vaginal swab samples via microscopy operated by highly skilled personnel. Hence, novel approaches for BV diagnosis are an existing need. In response, the first immunosensing platform targeting sialidase, a BV biomarker, is reported. The nanophotonic operational principle of this biosensing platform allows for a cheaper, faster, and simpler analysis when compared with an indirect enzyme-linked immunosorbent assay (ELISA). The clinical evaluation of such a nanotechnology is highlighted, where 162 vaginal swab samples were analyzed with high sensitivity and specificity (96.29%, respectively). The resulting nanoimmunosensing platform offers a resourceful approach to perform a timely BV diagnosis.

Recent advances in cultivation-independent molecular-based techniques for the characterization of vaginal eubiosis and dysbiosis

“The bacterial vaginosis syndrome” has significant adverse effects for women and babies, including preterm birth and increased risk of acquisition of sexually transmitted infections and HIV. Currently, the gold standard for diagnosis is Gram stain microscopy of vaginal secretions, which is not readily available, is somewhat subjective, and does not differentiate between the likely different subtypes of vaginal dysbioses that may have different etiologies, microbiology, responses to antibiotics, and phenotypic outcomes. With new information from molecular-based, cultivation-independent studies, there is increasing interest in the use of molecular techniques for the diagnosis of bacterial vaginosis. We reviewed the current evidence on and the rationale behind the use of molecular techniques for the diagnosis of bacterial vaginosis. We found a number of commercially available molecular diagnostic tests, a few of which have US Food and Drug Administration (FDA) and/or Conformité Européenne in vitro diagnostic (CE-IVD) approval, and we have compared their performance with respect to sensitivities and specificities. Molecular-based tests have the advantage of objectivity, quantification, detection of fastidious organisms, and validity for self-obtained vaginal swabs. The performance of the molecular tests against standard microscopy is impressive, but further education of users on interpretation is needed. Bacterial vaginosis is the major cause of vaginal dysbiosis and should be recognized for the threat it is to women’s genital tract health. Quantitative assessment of microbial abundance, the diversity of other organisms present, specific primers for gene sequence regions, and clades and biovars of target microbes should be recognized and incorporated into future molecular diagnostic tests to better differentiate between vaginal eubiosis and dysbiosis.

The Cervicovaginal Mucus Barrier

Preterm births are a global health priority that affects 15 million babies every year worldwide. There are no effective prognostic and therapeutic strategies relating to preterm delivery, but uterine infections appear to be a major cause. The vaginal epithelium is covered by the cervicovaginal mucus, which is essential to health because of its direct involvement in reproduction and functions as a selective barrier by sheltering the beneficial lactobacilli while helping to clear pathogens. During pregnancy, the cervical canal is sealed with a cervical mucus plug that prevents the vaginal flora from ascending toward the uterine compartment, which protects the fetus from pathogens. Abnormalities of the cervical mucus plug and bacterial vaginosis are associated with a higher risk of preterm delivery. This review addresses the current understanding of the cervicovaginal mucus and the cervical mucus plug and their interactions with the microbial communities in both the physiological state and bacterial vaginosis, with a focus on gel-forming mucins. We also review the current state of knowledge of gel-forming mucins contained in mouse cervicovaginal mucus and the mouse models used to study bacterial vaginosis.

Production and characterization of a monoclonal antibody against the sialidase of Gardnerella vaginalis using a synthetic peptide in a MAP8 format

Abstract

Bacterial vaginosis is one of the most frequent vaginal infections. Its main etiological agent is Gardnerella vaginalis, which produces several virulence factors involved in vaginal infection and colonization, in particular, sialidase (SLD), a potential clinical biomarker that participates in immune response modulation and mucus degradation. The main objective of this work was the production and evaluation of a monoclonal antibody against G. vaginalis sialidase and its validation in immunoassays. For immunization of mice, a synthetic multiantigenic peptide was used, and hybridomas were generated. After fusion, hybridomas were evaluated for antibody production and cloned by limited dilution. One clone producing IgG1 was selected and characterized by indirect ELISA, dot blot, and Western blot, and we also tested clinical isolates and HeLa cells infected with G. vaginalis. The results showed that the anti-SLD antibody recognized a single protein of ~90 kDa that correlated with the estimated molecular weight of SLD. In addition, anti-SLD antibody recognized SLD from complete bacteria and from culture supernatants of infected Hela cells. In conclusion, our results showed that the anti-SLD antibody recognized SLD from different sources and could be considered a new tool for the diagnosis of bacterial vaginosis.

Key Points

• Anti-sialidase mAb was generated using a synthetic peptide

• The mAb recognizes synthetic peptide and intact protein from multiple sources

• The antibody was characterized by several immunological methods

Cervicovaginal Microbiota and Reproductive Health: The Virtue of Simplicity

Cervicovaginal microbiota play a critical role in women's health and reproductive outcomes. Despite being one of the simplest commensal bacterial communities in the human body, we are only beginning to appreciate its complex dynamic nature and important role in host immune modulation. In this review, we discuss the "optimal" cervicovaginal bacterial community composition, the impact of microbiota on gynecologic and obstetric outcomes, and the hurdles to developing a deeper mechanistic understanding of the function of the cervicovaginal microbiome. We then describe efforts to durably alter microbial composition in this compartment by promotion of Lactobacillus colonization with probiotics, modulation of vaginal pH, hormonal administration, and the eradication of pathogenic bacteria with antibiotics. Finally, we draw on lessons learned from the deeply investigated gut microbiome to suggest future avenues of research into host-pathogen interactions in the female genital tract.

Phenotypic characterization of Gardnerella vaginalis subgroups suggests differences in their virulence potential

The well-known genotypic and phenotypic diversity of G. vaginalis resulted in its classification into at least four subgroups (clades) with diverse genomic properties. To evaluate the virulence potential of G. vaginalis subgroups, we analyzed the virulence-related phenotypic characteristics of 14 isolates of clade 1, 12 isolates of clade 2, 8 isolates of clade 4 assessing their in vitro ability to grow as a biofilm, produce the toxin vaginolysin, and express sialidase activity. Significant differences in VLY production were found (p = 0.023), but further analysis of clade pairs did not confirm this finding. The amount of biofim did not differ significantly among the clades. Analysis of sialidase activity indicated statistically significant differences among the clades (p < 0.001). Production of active recombinant G. vaginalis sialidase demonstrated the link between the sld gene and enzymatic activity, which may be differentially regulated at the transcriptional level. Statistical classification analysis (random forests algorithm) showed that G. vaginalis clades could be best defined by the profiles of two phenotypic characteristics: sialidase activity and vaginolysin production. The results of principal component analysis and hierarchical clustering suggested that all isolates can be subgrouped into three clusters, the structures of which are determined based on phenotypic characteristics of the isolates. Clade 4 was the most homogenous group, as all isolates were found in the same cluster, which is characterized by low production of all studied virulence factors. Clade 2 isolates were mainly distributed between two clusters, whereas clade 1 isolates were found in all three clusters that were characterized by a distinct profile of phenotypic characteristics. Our findings suggest that G. vaginalis subgroups with different virulence potential might play distinct roles in vaginal microbiota.

The Effects of Hormones and Vaginal Microflora on the Glycome of the Female Genital Tract: Cervical-Vaginal Fluid

In this study, we characterized the glycome of cervical-vaginal fluid, collected with a Catamenial cup. We quantified: glycosidase levels; sialic acid and high mannose specific lectin binding; mucins, MUC1, MUC4, MUC5AC, MUC7; and albumin in the samples collected. These data were analyzed in the context of hormonal status (day of menstrual cycle, hormonal contraception use) and role, if any, of the type of the vaginal microflora present. When the Nugent score was used to stratify the subjects by microflora as normal, intermediate, or bacterial vaginosis, several important differences were observed. The activities of four of six glycosidases in the samples from women with bacterial vaginosis were significantly increased when compared to normal or intermediate women: sialidase, P = <0.001; α-galactosidase, P = 0.006; β-galactosidase, P = 0.005; α-glucosidase, P = 0.056. Sialic acid binding sites as measured by two lectins, Maackia amurensis and Sambucus nigra binding, were significantly lower in women with BV compared to women with normal and intermediate scores (P = <0.0001 and 0.008 respectively). High mannose binding sites, a measure of innate immunity were also significantly lower in women with BV (P = <0.001). Additionally, we observed significant increases in MUC1, MUC4, MUC5AC, and MUC7 concentrations in women with BV (P = <0.001, 0.001, <0.001, 0.02 respectively). Among normal women we found that the membrane bound mucin MUC4 and the secreted MUC5AC were decreased in postmenopausal women (P = 0.02 and 0.07 respectively), while MUC7 (secreted) was decreased in women using levonorgestrel-containing IUDs (P = 0.02). The number of sialic acid binding sites was lower in the postmenopausal group (P = 0.04), but the number of high mannose binding sites, measured with Griffithsin, was not significantly different among the 6 hormonal groups. The glycosidase levels in the cervical-vaginal mucus were rather low in the groups, with exception of α-glucosidase activity that was much lower in the postmenopausal group (P<0.001). These studies present compelling evidence that the vaginal ecosystem responds to the presence of different vaginal microorganisms. These effects were so influential that it required us to remove subjects with BV for data interpretation of the impact of hormones. We also suggest that certain changes occurring in vaginal/cervical proteins are due to bacteria or their products. Therefore, the quantitation of vaginal mucins and lectin binding offers a new method to monitor bacteria-host interactions in the female reproductive tract. The data suggest that some of the changes in these components are the result of host processing, such as the increases in mucin content, while the microflora is responsible for the increases in glycosidases and the decreases in lectin binding. The methods should be considered a valid marker for insult to the female genital tract.

Vaginal Mucosal Homeostatic Response May Determine Pregnancy Outcome in Women With Bacterial Vaginosis: A Pilot Study

Bacterial vaginosis (BV) is considered as a trigger for an inflammatory response that could promote adverse pregnancy outcome (APO). We hypothesized that BV-related inflammation could be counterbalanced by anti-inflammatory and mucosal homeostatic responses that could participate in pregnancy outcomes.A total of 402 vaginal self-samples from pregnant women in their first trimester were screened by Nugent score. In this population, we enrolled 23 pregnant women with BV but without APO, 5 pregnant women with BV and developing APO, 21 pregnant women with intermediate flora, and 28 random control samples from pregnant women without BV or APO.BV without APO in pregnant women was associated with 28-fold interleukin-8, 5-fold interleukin-10, and 40-fold interleukin-22 increases in expression compared to controls. BV associated with APO in pregnant women shared 4-fold increase in tumor necrosis factor, 100-fold decrease in interleukin-10, and no variation in interleukin-22 expressions compared to controls. Next-generation sequencing of vaginal microbiota revealed a shift from obligate anaerobic bacteria dominance in BV without APO pregnant women to Lactobacillus dominance microbiota in BV with APO.Our results show that the anti-inflammatory and mucosal homeostatic responses to BV may determine outcome of pregnancy in the setting of BV possibly through effects on the vaginal microbiota.

Impact of bacterial vaginosis, as assessed by nugent criteria and hormonal status on glycosidases and lectin binding in cervicovaginal lavage samples

The objective of this study was to evaluate the impact of hormonal status and bacterial vaginosis (BV) on the glycosidases present and glycosylation changes as assessed by lectin binding to cervicovaginal lavage constituents. Frozen cervicovaginal lavage samples from a completed study examining the impact of reproductive hormones on the physicochemical properties of vaginal fluid were utilized for the present study. In the parent study, 165 women were characterized as having BV, intermediate or normal microflora using the Nugent criteria. The presence of glycosidases in the samples was determined using quantitative 4-methyl-umbelliferone based assays, and glycosylation was assessed using enzyme linked lectin assays (ELLA). Women with BV had elevated sialidase, α-galactosidase, β-galactosidase and α-glucosidase activities compared to intermediate or normal women (P<0.001, 0.003, 0.006 and 0.042 respectively). The amount of sialic acid (Sambucus nigra, P = 0.003) and high mannose (griffithsin, P<0.001) were reduced, as evaluated by lectin binding, in women with BV. When the data were stratified according to hormonal status, α-glucosidase and griffithsin binding were decreased among postmenopausal women (P<0.02) when compared to premenopausal groups. These data suggest that both hormonal status and BV impact the glycosidases and lectin binding sites present in vaginal fluid. The sialidases present at increased levels in women with BV likely reduce the number of sialic acid binding sites. Other enzymes likely reduce griffithsin binding. The alterations in the glycosidase content, high mannose and sialic acid binding sites in the cervicovaginal fluid associated with bacterial vaginosis may impact susceptibility to viruses, such as HIV, that utilize glycans as a portal of entry.

Selecting anti-microbial treatment of aerobic vaginitis

Aerobic vaginitis (AV) is a vaginal infectious condition which is often confused with bacterial vaginosis (BV) or with the intermediate microflora as diagnosed by Nugent's method to detect BV on Gram-stained specimens. However, although both conditions reflect a state of lactobacillary disruption in the vagina, leading to an increase in pH, BV and AV differ profoundly. While BV is a noninflammatory condition composed of a multiplex array of different anaerobic bacteria in high quantities, AV is rather sparely populated by one or two enteric commensal flora bacteria, like Streptococcus agalactiae, Staphylocuccus aureus, or Escherichia coli. AV is typically marked by either an increased inflammatory response or by prominent signs of epithelial atrophy or both. The latter condition, if severe, is also called desquamative inflammatory vaginitis. As AV is per exclusionem diagnosed by wet mount microscopy, it is a mistake to treat just vaginal culture results. Vaginal cultures only serve as follow-up data in clinical research projects and are at most used in clinical practice to confirm the diagnosis or exclude Candida infection. AV requires treatment based on microscopy findings and a combined local treatment with any of the following which may yield the best results: antibiotic (infectious component), steroids (inflammatory component), and/or estrogen (atrophy component). In cases with Candida present on microscopy or culture, antifungals must be tried first in order to see if other treatment is still needed. Vaginal rinsing with povidone iodine can provide rapid relief of symptoms but does not provide long-term reduction of bacterial loads. Local antibiotics most suitable are preferably non-absorbed and broad spectrum, especially those covering enteric gram-positive and gram-negative aerobes, like kanamycin. To achieve rapid and short-term improvement of severe symptoms, oral therapy with amoxyclav or moxifloxacin can be used, especially in deep dermal vulvitis and colpitis infections with group B streptococci or (methicillin resistant) Staphylococcus aureus. Since the latter colonizations are frequent, but seldom inflammatory infections, we in general discourage the use of oral antibiotics in women with AV. In cases with a severe atrophy component (more than 10 % of epithelial cells are of the parabasal type), local estrogens can be used; and in postmenopausal or breast cancer patients with a contraindication for estrogens, even a combination of probiotics with an ultra-low dose of local estriol may be considered.

Performance of BVBlue rapid test in detecting bacterial vaginosis among women in Mysore, India

Bacterial vaginosis (BV) is the most common cause of abnormal vaginal discharge in reproductive age women. It is associated with increased susceptibility to HIV/STI and adverse birth outcomes. Diagnosis of BV in resource-poor settings like India is challenging. With little laboratory infrastructure there is a need for objective point-of-care diagnostic tests. Vaginal swabs were collected from women 18 years and older, with a vaginal pH>4.5 attending a reproductive health clinic. BV was diagnosed with Amsel's criteria, Nugent scores, and the OSOM BVBlue test. Study personnel were blinded to test results. There were 347 participants enrolled between August 2009 and January 2010. BV prevalence was 45.1% (95% confidence interval (CI): 41.5%-52.8%) according to Nugent score. When compared with Nugent score, the sensitivity, specificity, positive predictive value, negative predictive value for Amsel's criteria and BVBlue were 61.9%, 88.3%, 81.5%, 73.7% and 38.1%, 92.7%, 82.1%, 63.9%, respectively. Combined with a "whiff" test, the performance of BVBlue increased sensitivity to 64.4% and negative predictive value to 73.8%. Despite the good specificity, poor sensitivity limits the usefulness of the BVBlue as a screening test in this population. There is a need to examine the usefulness of this test in other Indian populations.

Role of pore-forming toxins in bacterial infectious diseases

Pore-forming toxins (PFTs) are the most common bacterial cytotoxic proteins and are required for virulence in a large number of important pathogens, including Streptococcus pneumoniae, group A and B streptococci, Staphylococcus aureus, Escherichia coli, and Mycobacterium tuberculosis. PFTs generally disrupt host cell membranes, but they can have additional effects independent of pore formation. Substantial effort has been devoted to understanding the molecular mechanisms underlying the functions of certain model PFTs. Likewise, specific host pathways mediating survival and immune responses in the face of toxin-mediated cellular damage have been delineated. However, less is known about the overall functions of PFTs during infection in vivo. This review focuses on common themes in the area of PFT biology, with an emphasis on studies addressing the roles of PFTs in in vivo and ex vivo models of colonization or infection. Common functions of PFTs include disruption of epithelial barrier function and evasion of host immune responses, which contribute to bacterial growth and spreading. The widespread nature of PFTs make this group of toxins an attractive target for the development of new virulence-targeted therapies that may have broad activity against human pathogens.

Sialidase activity in aerobic vaginitis is equal to levels during bacterial vaginosis

OBJECTIVE

To evaluate levels of proinflammatory cytokines and sialidase activity in aerobic vaginitis (AV) in relation to normal vaginal flora and bacterial vaginosis (BV).

STUDY DESIGN

In this cross-sectional study, a total of 682 consecutive non-pregnant women attending the gynecology service were assessed and 408 women were included. Vaginal rinsing samples were collected from 223 women with microscopic finding of BV (n=98), aerobic vaginitis (n=25) and normal flora (n=100). Samples were tested for interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)-α, and sialidase activity.

RESULTS

Compared to women with normal flora, vaginal levels of IL-1β were highly increased in both BV and AV (p<0.0001). Significantly higher vaginal IL-6 was detected in AV (p<0.0001) but not in BV, in relation to normal flora. Women with AV also presented increased IL-8 levels (p<0.001), while those with BV presented levels similar to normal flora. Sialidase was increased in BV and AV compared with the normal group (p<0.0001) but no difference in sialidase activity was observed between BV and AV.

CONCLUSION

A more intense inflammatory host response occurs for AV than for BV when compared with normal flora. Furthermore, the increased sialidase activity in AV and BV indicates that both abnormal vaginal flora types can be harmful to the maintenance of a healthy vaginal environment.

Polymicrobial challenges to Koch's postulates: ecological lessons from the bacterial vaginosis and cystic fibrosis microbiomes

Koch's postulates have shaped our understanding of infectious diseases; however, one of the tangential consequences of them has been the emergence of a predominantly monomicrobial perspective concerning disease aetiology. This orthodoxy has been undermined by the growing recognition that some important infectious diseases have a polymicrobial aetiology. A significant new development in our understanding of polymicrobial infections is the recognition that they represent functional ecosystems and that to understand such systems and the outcome and impact of therapeutic interventions requires an understanding of how these communities arise and develop. Therefore, it is timely to explore what we can learn from other fields. In particular, ecological theory may inform our understanding of how polymicrobial communities assemble their structure and their dynamics over time. Such work may also offer insights into how such communities move from stable to unstable states, as well as the role of invasive pathogens in the progression of the disease. Ecological theory offers a theoretical framework around which testable hypotheses can be developed to clarify the polymicrobial nature and dynamics of such infections in the face of environmental change and therapeutic interventions.

Gardnerella vaginalis comprises three distinct genotypes of which only two produce sialidase

OBJECTIVE

Sialidase and the presence of Gardnerella vaginalis have been proposed as biomarkers for bacterial vaginosis. Sialidase has been associated with adverse pregnancy outcome. We genotyped G vaginalis isolates, assessed the presence and diversity of sialidase-encoding genes, and determined the production of sialidase.

STUDY DESIGN

One hundred thirty-four G vaginalis isolates were genotyped by random amplified polymorphic deoxyribonucleic acid (RAPD) and a selection of 29 isolates with amplified ribosomal deoxyribonucleic acid restriction analysis (ARDRA). A G vaginalis sialidase quantitative polymerase chain reaction was developed, and the sialidase production was assessed with the filter spot test.

RESULTS

Three G vaginalis genotypes could be distinguished by both RAPD and ARDRA. Only 2 genotypes encoded and produced sialidase.

CONCLUSION

Three genotypes exist among G vaginalis isolates, and there is a clear link between genotype and sialidase production. A possible link between sialidase production and (symptomatic) bacterial vaginosis and biofilm production can be hypothesized.

High sialidase levels increase preterm birth risk among women who are bacterial vaginosis-positive in early gestation

OBJECTIVE

The purpose of this study was to assess whether vaginal sialidases level in early pregnancy is associated with preterm birth among women who are bacterial vaginosis-positive.

STUDY DESIGN

Of the 1806 women who were enrolled at < 20 weeks of gestation, 800 of the women were bacterial vaginosis-positive (Nugent score, 7-10); 707 of the women had birth outcome data; 109 of the women who were bacterial vaginosis-positive had an adverse preterm outcome, which included 53 spontaneous preterm births (19 births were early at 20-34 weeks, and 34 births were late at 34-37 weeks), and 14 of the women had late miscarriages (12-20 weeks). Sialidase levels were compared with 352 control subjects (term normal birthweight infants).

RESULTS

Sialidase levels at ≥ 5, ≥ 10, and ≥ 14 nmol (odds ratio [OR], 1.56; 95% confidence interval [CI], 1.01-2.41; OR, 2.14; 95% CI, 1.25-3.64; OR, 3.17; 95% CI, 1.64-6.10, respectively) was associated significantly with all adverse preterm outcomes. The ≥ 10 nmol and ≥ 14 nmol cut-points were associated strongly with early spontaneous preterm births (OR, 3.79; 95% CI, 1.42-10.10 and OR, 5.36; 95% CI, 1.77-16.23, respectively) and late miscarriages (OR, 4.87; 95% CI, 1.61-14.65; OR, 8.33; 95% CI, 2.57-26.9, respectively).

CONCLUSION

Elevated sialidase level that is measured at 12 weeks of gestation is associated strongly with early spontaneous preterm births and late miscarriage.

The vaginal microbiome: new information about genital tract flora using molecular based techniques

Vaginal microbiome studies provide information that may change the way we define vaginal flora. Normal flora appears dominated by one or two species of Lactobacillus. Significant numbers of healthy women lack appreciable numbers of vaginal lactobacilli. Bacterial vaginosis (BV) is not a single entity, but instead consists of different bacterial communities or profiles of greater microbial diversity than is evident from cultivation-dependent studies. BV should be considered a syndrome of variable composition that results in different symptoms, phenotypical outcomes, and responses to different antibiotic regimens. This information may help to elucidate the link between BV and infection-related adverse outcomes of pregnancy.

Gardnerella vaginalis septicaemia with pyelonephritis, infective endocarditis and septic emboli in the kidney and brain of an adult male

Gardnerella vaginalis is typically associated with bacterial vaginosis in women. However, balanitis, urethritis, urinary tract infections and asymptomatic bacteraemia have also been described in men. Here we report a case of G. vaginalis septicaemia with infective endocarditis and septic emboli in the kidney and brain of an adult male.

Comparative genomics of Gardnerella vaginalis strains reveals substantial differences in metabolic and virulence potential

BACKGROUND

Gardnerella vaginalis is described as a common vaginal bacterial species whose presence correlates strongly with bacterial vaginosis (BV). Here we report the genome sequencing and comparative analyses of three strains of G. vaginalis. Strains 317 (ATCC 14019) and 594 (ATCC 14018) were isolated from the vaginal tracts of women with symptomatic BV, while Strain 409-05 was isolated from a healthy, asymptomatic individual with a Nugent score of 9.

PRINCIPAL FINDINGS

Substantial genomic rearrangement and heterogeneity were observed that appeared to have resulted from both mobile elements and substantial lateral gene transfer. These genomic differences translated to differences in metabolic potential. All strains are equipped with significant virulence potential, including genes encoding the previously described vaginolysin, pili for cytoadhesion, EPS biosynthetic genes for biofilm formation, and antimicrobial resistance systems, We also observed systems promoting multi-drug and lantibiotic extrusion. All G. vaginalis strains possess a large number of genes that may enhance their ability to compete with and exclude other vaginal colonists. These include up to six toxin-antitoxin systems and up to nine additional antitoxins lacking cognate toxins, several of which are clustered within each genome. All strains encode bacteriocidal toxins, including two lysozyme-like toxins produced uniquely by strain 409-05. Interestingly, the BV isolates encode numerous proteins not found in strain 409-05 that likely increase their pathogenic potential. These include enzymes enabling mucin degradation, a trait previously described to strongly correlate with BV, although commonly attributed to non-G. vaginalis species.

CONCLUSIONS

Collectively, our results indicate that all three strains are able to thrive in vaginal environments, and therein the BV isolates are capable of occupying a niche that is unique from 409-05. Each strain has significant virulence potential, although genomic and metabolic differences, such as the ability to degrade mucin, indicate that the detection of G. vaginalis in the vaginal tract provides only partial information on the physiological potential of the organism.

Randomized controlled trial of probiotics for the prevention of spontaneous preterm delivery associated with intrauterine infection: study protocol

BACKGROUND

Spontaneous preterm deliveries that occur before the 34th week of gestation, and particularly before the 32nd week of gestation, have been strongly associated to intrauterine infection, ascending from vagina, and represent the largest portion of neonatal deaths and neurological problems. Bacterial vaginosis, characterized by a diminished or absent flora of lactobacilli and increased colonization of several anaerobic or facultative microorganisms, increases two times the risk of preterm delivery before the 34th week. Trials of antibiotics failed to show efficacy and effectiveness against spontaneous preterm birth related to bacterial vaginosis. Some studies indicate benefit from selected probiotics to treat genitourinary infections, including bacterial vaginosis.

OBJECTIVE

The purpose of this study is to evaluate the effectiveness of the early administration of selected probiotics to pregnant women with asymptomatic bacterial vaginosis/intermediate degree infection to reduce the occurrence of spontaneous preterm delivery and related neonatal mortality and morbidity.

METHODS/DESIGN

Women attending public prenatal care services in Rio de Janeiro will be screened to select asymptomatic pregnant women, less than 20 weeks' gestation, with no indication of elective preterm delivery. Those with vaginal pH > = 4.5 and a Nugent score between 4 and 10 (intermediate degree infection or bacterial vaginosis) will be randomized to either the placebo or the intervention group, after written informed consent. Intervention consists in the use of probiotics, Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14, 2 capsules a day, each capsule containing more than one million bacilli of each strain, for 6-12 weeks, up to the 24th-25th wk of gestation. Ancillary analyses include quantification of selected cervicovaginal cytokines and genotyping of selected polymorphisms. The randomization process is stratified for history of preterm delivery and blocked. Allocation concealment was designed as well as blinding of women, caregivers and outcome evaluators. The study will be supervised by an independent monitoring committee. Outcomes under study are preterm delivery (< 34- < 32 weeks of gestation) and associated neonatal complications: early neonatal sepsis, bronchopulmonary dysplasia, periventricular leukomalacia, necrotizing enterocolitis, and prematurity-related retinopathy; definitions were adapted from those recommended by the 2002 version of the Vermont-Oxford Network. Trial registration at NIH register: NCT00303082.

Serum proinflammatory cytokine - interleukin-8 as possible infection site marker in preterm deliveries

AIM

To evaluate serum level of proinflammatory cytokine interleukin-8 as a biochemical marker of local infections in patients with clinical symptoms of preterm deliveries.

METHODS

We studied 74 pregnant women at 24-36 gestational weeks (GW) with preterm delivery. Serum interleukin-8 was measured.

RESULTS

The mean value of interleukin-8 in the study group (n=36) was 19.13 pg/mL vs. 5.02 pg/mL in the controls (n=38).

CONCLUSIONS

The results indicate that serum level of interleukin-8 might be used as non-invasive marker of infections in pregnancy, as well as a marker of preterm deliveries.

Efficacy of an acidic vaginal gel on vaginal pH and interleukin-6 levels in low-risk pregnant women: a double-blind, randomized placebo-controlled trial

BACKGROUND

Increased interleukin-6 (IL-6) levels and a vaginal pH of > 4.7 are associated with obstetric complications such as preterm delivery and low birth weight. Topical treatments, able to maintain a physiological vaginal pH, could help in the prevention of vaginal infections.

STUDY AIM

In a randomized, double-blind, placebo-controlled trial, we evaluated the effects of an acidic buffering vaginal gel (Miphil) on vaginal pH and IL-6 levels in pregnant women.

PATIENTS AND METHODS

Seventy low-risk women pregnant with a singleton (second trimester) were enrolled in the trial. Thirty-five were randomized to the acidic gel, 2.5 g every 3 days for 12 weeks, and 35 to the corresponding placebo. Vaginal pH and vaginal IL-6 level were measured at baseline and after 12 weeks. Women were then followed until delivery. The main outcome measures were vaginal pH, vaginal pH normalization (pH < 4.5) and vaginal IL-6 levels.

RESULTS

Vaginal pH at baseline was 4.6 +/- 0.4 and 4.4 +/- 0.3 in the acidic gel and the placebo group, respectively. At baseline, a total of 40% (14/35) and 22% (8/35) of women in each group, respectively, had a vaginal pH of > or = 4.7. At week 12, the vaginal pH was 4.3 +/- 0.3 in the acidic gel group and 4.3 +/- 0.3 in the placebo group (NS). The acidic gel normalized the vaginal pH in ten out of 14 women (p = 0.04) in comparison with only one out of eight women in the placebo group (NS). The acidic gel induced a significant (p < 0.02) reduction of vaginal IL-6 from 12.0 +/- 7 to 8.9 +/- 5 pg/l (-36%). In the placebo group, IL-6 increased from 9.0 +/- 5 to 13.5 +/- 6.8 pg/l (+50%) (p = 0.05). Birth weight was 2978 +/- 700 g in the placebo group and 3241 +/- 477 g in the acidic gel group (p = 0.06).

CONCLUSIONS

The use of the acidic gel in low-risk pregnant women is able to maintain a physiological vaginal ecosystem and prevents the increases of vaginal pH and vaginal IL-6. Prospective and controlled trials are warranted to evaluate whether this acidic gel can reduce obstetric complications linked to vaginal inflammation during pregnancy.

Oleate lipase activity in Gardnerella vaginalis and reconsideration of existing biotype schemes

BACKGROUND

Gardnerella vaginalis is a facultative gram positive organism that requires subculture every 1-2 days to maintain viability. It has been linked with bacterial vaginosis (BV), a syndrome that has been associated with increased risk for preterm delivery, pelvic inflammatory disease and HIV acquisition. About 10% of the G. vaginalis isolates have been reported to produce sialidase, but there have not been any studies relating sialidase production and biotype. Sialidase activity is dramatically increased in the vaginal fluid of women with BV and bacterial sialidases have been shown to increase the infectivity of HIV in vitro. There are 8 different biotypes of G. vaginalis. Biotypes 1-4 produce lipase and were reported to be associated with BV and the association of these biotypes with BV is under dispute. Other studies have demonstrated that G. vaginalis biotype 1 can stimulate HIV-1 production. Because of the discrepancies in the literature we compared the methods used to biotype G. vaginalis and investigated the relationship of biotype and sialidase production.

RESULTS

A new medium for maintenance of Gardnerella vaginalis which allows survival for longer than one week is described. Some isolates only grew well under anaerobic conditions. Sialidase producing isolates were observed in 5 of the 6 biotypes tested. Using 4-methylumbelliferyl-oleate to determine lipase activity, instead of egg yolk agar, resulted in erroneous biotypes and does not provide reliable results.

CONCLUSION

Previous studies associating G. vaginalis biotype with bacterial vaginosis were methodologically flawed, suggesting there is not an association of G. vaginalis biotypes and bacterial vaginosis. Sialidase activity was observed in 5 of the 8 biotypes.

Among pregnant women with bacterial vaginosis, the hydrolytic enzymes sialidase and prolidase are positively associated with interleukin-1beta

OBJECTIVE

The objective of the study was to explore the mechanisms of local innate immunity induction and modulation in pregnant women with bacterial vaginosis (BV).

STUDY DESIGN

A total of 200 singleton pregnant women in early gestation (12 +/- 4 weeks) with BV (Nugent 7-10) without concurrent vaginal infections with Trichomonas vaginalis, Chlamydia trachomatis, Neisseria gonorrhoeae, syphilis, and yeast. Concentrations of vaginal interleukin (IL)-1beta and IL-8, the number of neutrophils, and the levels of sialidase and prolidase hydrolytic enzymes were determined in vaginal fluid.

RESULTS

Concentrations of vaginal IL-1beta had a strong positive correlation with levels of sialidase (P < .001) and prolidase (P < .001). Conversely, such enzymes were negatively correlated with the ratio of IL-8/IL-1beta (both P < .001) and were not significantly associated with concentrations of IL-8. Notably, the number of vaginal neutrophils had a negative correlation with sialidase (P = .007).

CONCLUSION

The strong induction of IL-1beta in BV-positive women appears to be associated with the production of the hydrolytic enzymes sialidase and prolidase by BV-associated bacteria. However, these 2 enzymes may inhibit the expected amplification of the proinflammatory IL-1beta cascade as evaluated by the down-regulation of the IL-8/IL-1beta ratio. A blunted response to IL-1beta signals may cause the poor rise of neutrophils, which is peculiar to BV. This impairment of local defense may contribute to increased susceptibility to adverse outcomes in BV-positive pregnant women.

Gardnerella vaginalis bacteremia in a previously healthy man: case report and characterization of the isolate

Gardnerella vaginalis in women causes vaginitis or infections in other sites, such as the urinary tract, but is an infrequent cause of bacteremia. Bacteremia in men is very rare and is typically associated with immunocompromised states. Here we describe G. vaginalis bacteremia in a previously healthy man with renal calculi and urosepsis.

Definition and classification of abnormal vaginal flora

Studying the vaginal microflora is not only fascinating, with many discoveries to be made, it is also a very practical way to help women get rid of bothersome and sometimes dangerous infections. Gram-stained vaginal preparations, Pap smears, specific cultures, and nucleic acid detection techniques can be used to diagnose the constituents of the vaginal flora, but in trained hands office-based microscopy of a fresh vaginal smear, preferably using a x400 magnification phase-contrast microscope, allows almost every diagnosis and combination of diagnoses imaginable. In this chapter I will address the pros and cons of the tools that are in use to study vaginal flora, and discuss the different types of bacterial flora and the difficulties encountered in reaching the correct diagnosis of pathological conditions. The 'intermediate flora' is addressed separately, and a new entity--'aerobic vaginitis'--is discussed. Future research should focus on the interaction between infecting microorganisms and host defence mechanisms, as both together generate the pathogenicity of these conditions.

Modulation of vaginal immune response among pregnant women with bacterial vaginosis by Trichomonas vaginalis, Chlamydia trachomatis, Neisseria gonorrhoeae, and yeast

OBJECTIVE

This study was undertaken to examine the influence of coinfections on vaginal innate and adaptive immunity, and microbial enzyme activities of pregnant women with bacterial vaginosis (BV).

STUDY DESIGN

The population consisted of 265 singleton pregnant women in early gestation (<20 weeks) with BV (Nugent 7-10) who had vaginal fluid collected for measurement of interleukin-1beta (IL-1beta) and IL-8 concentrations, number of neutrophils, immunoglobulin A against Gardnerella vaginalis (anti-Gvh IgA), and activities of microbial sialidase and prolidase.

RESULTS

Among women with BV, median levels of vaginal IL-1beta (4-fold, P = .005), IL-8 (4-fold, P < .001), and neutrophils (6-fold, P = .013) were greatly increased in women with T vaginalis with respect to women without any coinfection. Yeast increased the level of IL-8 (5-fold, P < .001), but not IL-1beta (P = .239) and neutrophils (P = .060). Chlamydia trachomatis and Neisseria gonorrhoeae had no effect on vaginal cytokines. None of the coinfections influenced vaginal anti-Gvh IgA, sialidase and prolidase activities.

CONCLUSION

The strong proinflammatory cytokine induction by T. vaginalis may contribute to the observed increase in preterm birth among BV positive women coinfected with T. vaginalis treated with metronidazole.

Assessing the relationship between preterm delivery and various microorganisms recovered from the lower genital tract

OBJECTIVE

To determine if the likelihood of preterm delivery is more dependent on the specific organisms present in the vagina than on the presence of bacterial vaginosis.

METHODS

We evaluated the vaginal fluid of a prospective cohort of women at 23-32 weeks of gestation with signs and symptoms of preterm labor and intact membranes. Forward stepwise logistic regression models were used to evaluate the relationship between preterm delivery and the presence of anaerobic bacteria, Gardnerella, ureaplasmas and mycoplasmas, and sialidase.

RESULTS

The cohort included 137 women, and complete delivery information was available for 134 of them. The rate of preterm delivery was 28% (37 of 134). Mycoplasma genitalium independently was associated with spontaneous preterm delivery (OR 3.48; 95% CI 1.41, 8.57). After controlling for this factor, none of the other variables were significantly prognostic for spontaneous preterm delivery (residual overall p = 0.19).

CONCLUSION

The presence of Mycoplasma genitalium in the vagina of pregnant women is an independent risk factor for spontaneous preterm delivery.

Variation in vaginal immune parameters and microbial hydrolytic enzymes in bacterial vaginosis positive pregnant women with and without Mobiluncus species

OBJECTIVE

This study was undertaken to assess if levels of interleukin-1beta (IL-1beta), IL-8, sialidase, prolidase and immunoglobulin A against Gardenerella vaginalis hemolysin (anti-Gvh IgA) in vaginal secretions differ between BV+ women with (M+) and without (M-) Mobiluncus spp.

STUDY DESIGN

Vaginal secretions were obtained from 265 women at their first prenatal care visit and assessed for all study parameters. Gram stain evaluation using Nugent criteria was performed and coinfection with sexually transmitted infections determined. Differences between BV+/M+ and BV+/M- women were evaluated using the chi2 statistic or Mann-Whitney test.

RESULTS

Of the 265 BV+ women, 43% (n = 113) were M+ of which 97% (n = 110) had Nugent scores of 9 or 10 . BV+/M+ women had elevated levels of sialidase (median value: 4.11 nmol vs 1.91 nmol of converted substrate; P = .003) but no difference in prolidase, anti-Gvh IgA, IL-1beta, IL-8, levels were found between the two groups. BV+/M- women had significantly higher rates of coinfection with Trichomonas vaginalis.

CONCLUSION

BV+/M+ women have higher vaginal concentrations of sialidase and lower rates of T. vaginalis compared with BV+/M- women. Further research is needed to assess the association of this, and other, microbiologic profiles to risk of adverse pregnancy outcome.

Clinical diagnosis of bacterial vaginosis

OBJECTIVE

To evaluate the accuracy of Amsel's criteria individually or in combinations of two for the clinical diagnosis of bacterial vaginosis.

METHODS

This cross-sectional study enrolled 135 women at UNICAMP, and evaluated Amsel's four clinical criteria. Sensitivity, specificity, positive and negative predictive values were calculated for each criterion individually, in combinations of two, and for the classic test with at least three criteria present. The Nugent method was used as gold standard.

RESULTS

The most sensitive individual criteria were pH and vaginal discharge (97%), the latter having lowest specificity (26%). The criterion with highest specificity was the presence of clue cells (86%). The combination of two criteria showed sensitivity of 83% to 93%, and specificity of 82% to 94%.

CONCLUSION

The accuracy of Amsel's clinical criteria individually or in combinations of two was as accurate as the presence of at least three criteria for the diagnosis of bacterial vaginosis.

Management of genital infections in pregnant women

PURPOSE OF REVIEW

To examine and evaluate ways of managing genital infections in pregnant women.

RECENT FINDINGS

The need to screen for sexually transmitted diseases during pregnancy depends on the prevalence of the condition, its pathogenesis and the cost-benefit analysis for a population or risk group. For a few genital infections with severe impact on the outcome of the pregnancy, such as syphilis and gonorrhoea, a 'screen and treat' policy is almost always cost-effective.

SUMMARY

Genital infections often remain unnoticed during pregnancy, as their signs and symptoms may be seen as part of the normal discomfort of pregnancy. Also it is sometimes not clear whether there are multiple partners or whether the partners have been treated, making re-infection after treatment highly likely. Partner tracing may be difficult, but the 'screen and treat' policy is usually the best solution.

Successful treatment of bacterial vaginosis with a policarbophil-carbopol acidic vaginal gel: results from a randomised double-blind, placebo-controlled trial

OBJECTIVE

We evaluated the efficacy of a mucoadhesive vaginal gel (MVG, Miphil) with acidic-buffering properties in bacterial vaginosis (BV).

STUDY DESIGN

Double-blind, placebo-controlled, 12-week trial.

SUBJECTS

A total of 45 non-pregnant women with BV were enrolled in the trial. Patients were treated with MVG 2.5 g or the corresponding placebo (P) daily for the first week and then every 3 days for the following 5 weeks (treatment phase) in a 2:1 ratio. All patients were followed for an additional 6 weeks without treatments (follow-up phase). Clinical cure was defined as absence of vaginal discharge, vaginal pH <4.5, a negative fish odour test and a Nugent score <7.

RESULTS

At week 6, 28 out of 30 women (93%) in the MVG group were clinically cured in comparison with only 1 out of 15 (6%) in the P group (P=0.0001). At week 12, 86% of MVG treated women remained cured in comparison with 8% in P group (P=0.0001). At baseline, the vaginal pH was 6.1+/-0.7 in the MVG and 5.5+/-0.7 in the P group. Vaginal pH significantly (P=0.003) decreased to 4.3+/-0.3 in the MVG group. In P group non-significant modifications of vaginal pH were observed (5.1+/-0.5).

CONCLUSION

Our results demonstrated that this MVG is an effective treatment of BV.

Bacterial vaginosis - a microbiological and immunological enigma. Review article

The development of bacterial vaginosis (BV) among women of childbearing age and the resulting quantitative and qualitative shift from normally occurring lactobacilli in the vagina to a mixture of mainly anaerobic bacteria is a microbiological and immunological enigma that so far has precluded the formulation of a unifying generally accepted theory on the aetiology and clinical course of BV. This critical review highlights some of the more important aspects of BV research that could help in formulating new basic ideas respecting the biology of BV, not least the importance of the interleukin mediators of local inflammatory responses and the bacterial shift from the normally occurring lactobacilli species: L. crispatus, L. gasseri, L. jensenii, and L. iners to a mixed flora dominated by anaerobic bacteria.

Combination of vaginal pH with vaginal sialidase and prolidase activities for prediction of low birth weight and preterm birth

OBJECTIVE

The purpose of this study was to assess if easy to measure vaginal fluid biomarkers are predictive for low birth weight (LBW, <2500 g), very LBW (VLBW, <1500 g), spontaneous preterm at <37 weeks' gestation, and total preterm deliveries (at <37, <35, <32 weeks' gestation).

STUDY DESIGN

Low and high cutoffs for vaginal fluid pH, sialidase, and prolidase activities were examined in a nested case-control study of 579 Danish women (from a study population of 2846 women) with samples collected at mean 17 weeks' gestation. One hundred sixteen LBW (17 VLBW), 117 preterm deliveries (85 spontaneous), and 418 normal term deliveries were analyzed.

RESULTS

Vaginal pH >/=4.7 or pH >/=5 by itself was not associated with LBW or prematurity. Conversely, combination of pH >/=5 and high sialidase activity demonstrated OR 17 (CI 1.8-150) for LBW; OR 31 (CI 1.8-516) for VLBW; along with OR 18 (CI 1.6-204) for preterm at <35 weeks'; and OR 31 (CI 1.9-542) for preterm at <32 weeks' gestation. The combination of pH >/=5 and high prolidase activity demonstrated OR 13 (CI 1.3-122) for LBW; OR 33 (CI 2.0-553) for VLBW, as well as OR 9.2 (CI 0.6-150) for preterm at <35 weeks'; and OR 35 (CI 2.0-586) for preterm at <32 weeks' gestation. In this population, no woman having high sialidase and high prolidase activity had a term birth, or a baby weighting >/=2500 g at birth.

CONCLUSION

In this Danish population, mid-gestation findings of vaginal fluid elevated pH with sialidase and/or prolidase were associated with LBW, VLBW, and early preterm at <35 or <32 weeks' gestation.

Increased Frequency of Bacterial Vaginosis and Chlamydia trachomatis in Pregnant Women with Human Papillomavirus Infection

The aim of this study was to verify the presence of bacterial vaginosis (BV), Candida sp, Chlamydia trachomatis, Neisseria gonorrhoeae, to determine the prevalence of tobacco use and measure vaginal pH (VpH) in pregnant women with (n = 26) and without (n = 26) human papillomavirus (HPV) infection, and make comparisons between these 2 groups. HPV, C. trachomatis and N. gonorrhoeae were diagnosed using hybrid capture, BV using clinical criteria, and Candida sp via cultures. A digital pH meter was used to measure VpH. The frequencies of Candida sp were 19.2 and 23.1% (p = 1), and VpH was 4.4 +/- 0.4 and 4.3 +/- 0.4 (p = 0.23), in the HPV-positive and HPV-negative groups, respectively. Compared to the group of pregnant women without HPV infection, those with HPV infection had a significantly higher prevalence of tobacco use (50 vs. 11.5%; p = 0.006), BV (53.8 vs. 15.4%; p = 0.007), and C. trachomatis (34.6 vs. 7.7%; p = 0.039). No case of N. gonorrhoeae was diagnosed. All cases of C. trachomatis and BV had high-grade HPV infection.

Vaginal Immunity in Bacterial Vaginosis

Vaginal immunity in response to microbial perturbation is still poorly understood and may be crucial for protection from adverse outcomes associated with bacterial vaginosis (BV). BV is the most prevalent vaginal disorder in adult women worldwide. However, its pathogenesis is still elusive. In BV-positive women, inflammatory signs are scant--approximately 50% of women are asymptomatic. The number of vaginal neutrophils in the BV-positive patient is not increased with respect to healthy women. In contrast, vaginal interleukin (IL)-1beta levels are largely increased. Recent findings indicate that microbial hydrolytic enzymes could be responsible for dampening the expected proinflammatory response cascade after IL-1beta increase. In other words, BV causes a large increase of vaginal IL-1beta, which is not paralleled by an increase of IL-8 levels, suggesting that BV-associated factors specifically dampen IL-8. The impairment of IL-8 increase may explain the absence of neutrophil increase in most women exposed to a massive abnormal anaerobic vaginal colonization (BV). Among BV-positive women, vaginal innate immunity is strongly correlated to a specific adaptive immune response: the immunoglobulin A (IgA) against the hemolysin produced by Gardnerella vaginalis (anti-Gvh IgA), which is the main bacterium present in BV. High anti-Gvh IgA levels are protective for adverse pregnancy outcomes. However, an exaggerated inflammatory response, mainly attributed to genetic polymorphisms, is also implicated in BV-associated adverse outcomes.

Nucleic acid-based diagnosis of bacterial vaginosis and improved management using probiotic lactobacilli

Bacterial vaginosis (BV) is a common condition in women that represents an imbalance of the vaginal microflora, lactobacilli depletion, and excess growth of mainly anaerobic Gram-negative pathogens. Diagnosis is made using a series of tests or a Gram stain of a vaginal smear. Treatment with antibiotics is quite effective, but recurrences are common. A study of 55 vaginal samples from 11 postmenopausal women showed the presence of BV by the Gram stain-based Nugent scoring system, and polymerase chain reaction-denaturing gradient gel electrophoresis showed that Bacteroides or Prevotella species were the most common isolates recovered (24 of 25), with Escherichia coli, Staphylococcus aureus, and Streptococcus agalactiae also found in some samples. In one case, only Gardnerella vaginalis was found. These findings illustrate that BV remains common even among otherwise healthy women, but it is not caused solely by either Gardnerella or Mobiluncus. Use of a FemExam system (Cooper Surgical, Shelton, CT), based upon elevated pH and trimethylamine levels, to screen vaginal smears from 59 healthy women showed poor correlation with the Gram stain method. A randomized, placebo-controlled trial of these subjects showed that the lactobacilli-dominant microbiota was restored in subjects with BV but not in controls, following 2 months of daily oral intake of Lactobacillus rhamnosus GR-1 and Lactobacillus fermentum RC-14. These studies show that nucleic acid-based methods are effective at identifying bacteria responsible for BV. If such methods could be used to develop a commercially available, self-use kit, women would be much better placed to take control of their own health, for example, using medicinal food or dietary supplement products such as the clinically proven probiotic strains L. rhamnosus GR-1 and L. fermentum RC-14.

Efficacy of the combination of 2 g oral tinidazole and acidic buffering vaginal gel in comparison with vaginal clindamycin alone in bacterial vaginosis: a randomized, investigator-blinded, controlled trial

OBJECTIVE

To evaluate the efficacy of tinidazole (T) (Trimonase, Mipharm, Italy) and an acidic vaginal gel (Miphil) (M) in comparison with vaginal clindamycin (CL) (Cleocin Pharmacia Upjohn) in BV.

DESIGN

A multicentre, randomised, investigator-blinded, controlled trial.

POPULATION AND METHODS

64 women with BV were enrolled. Thirty-two were allocated to receive oral T 2g, single dose, and 32 were assigned to CL 2% for 7 consecutive days. After week 1, T group were treated with an acidic vaginal gel, 2g every 3 days, for additional 3 weeks, whereas CL group did not received any additional treatment. Patients were evaluated at week 1 and 4. Vaginal pH, the BV-blue test (Gryphus Diagnostics, USA) and the whiff test were performed at baseline and at week 4.

MAIN OUTCOMES MEASURES

Clinical cure rate; normalisation of vaginal pH (pH<4.5); and laboratory cure rate (defined as a clinical cure rate and a negative results of BV-blue and whiff test).

RESULTS

At baseline, vaginal pH values were (mean+/-S.D.) 5.4+/-0.7 and 5.3+/-0.5 in T and CL groups, respectively. Six patients (2 in T group and 4 in CL group) withdrew from the study due to side effects. At week 1, the clinical cure rates were 84% in both T and CL treated group (P=N.S.). At week 4, clinical cure rates were 94% in T+M group and 77% in CL group (P=N.S.). The laboratory cure rates were 81% in T+M group and 59% in CL group (P<0.04). Vaginal pH normalisation (i.e. pH <4.5) was achieved in 78% and in 38% of T+M and CL groups, respectively (P<0.0007).

CONCLUSIONS

In the short term, 2g single oral dose tinidazole was at least as effective as 7-day of vaginal clindamycin. The sequential treatment of tinidazole and acidic vaginal gel was superior to vaginal clindamycin in lowering vaginal pH and achieving a higher laboratory tests normalization rate at 1-month follow-up.

BVBlue test for diagnosis of bacterial vaginosis

Bacterial vaginosis (BV) is a disorder of the vaginal ecosystem characterized by a shift in the vaginal flora from the normally predominant Lactobacillus to one dominated by sialidase enzyme-producing mixed flora. It is the most common cause of abnormal vaginal discharge in adult women. The BVBlue system (Gryphus Diagnostics, L.L.C.) is a chromogenic diagnostic test based on the presence of elevated sialidase enzyme in vaginal fluid samples. BVBlue was compared to the standard method for diagnosing BV (Amsel criteria and Nugent score). Fifty-seven nonmenstruating women of > or =16 years of age who presented for a pelvic examination were recruited. Demographic features were collected via a self-administered questionnaire. The Amsel criteria were assessed based on three of four of the following characteristics of vaginal discharge: consistency, odor, pH, and presence of clue cells on Gram stain. BVBlue was compared to the Gram stain and Amsel criteria. The sensitivity, specificity, positive predictive value, and negative predictive value for BVBlue versus the Gram stain and Amsel criteria were 91.7, 97.8, 91.7, and 97.8% and 50.0, 100, 100, and 88.2%, respectively. A significantly greater proportion of patients with a vaginal pH of >4.5, a positive amine test, or with clue cells on vaginal Gram smear were found to have a positive BVBlue test (P < 0.001). Women previously treated for BV were 2.98 times more likely to have another episode of BV. BVBlue is a useful point-of-care diagnostic tool to provide a presumptive diagnosis of BV, especially in situations where microscopic capabilities are unavailable.

Glycosidase and proteinase activity of anaerobic gram-negative bacteria isolated from women with bacterial vaginosis

BACKGROUND

It is known that glycosidases and proteases are produced by the anaerobic gram-negative bacteria associated with bacterial vaginosis (BV). We hypothesized that these enzymes enzymatically degrade mucins, thereby destroying the mucus gel that otherwise helps protect against sexually transmitted pathogens, including HIV.

GOAL

The goal was to determine glycosidase and protease production by vaginal bacteria associated with BV and to compare these with symptoms and signs of abnormal discharge and to test vaginal fluid viscosity.

STUDY DESIGN

The anaerobic gram-negative rods recovered from the vaginas of 153 women with normal flora, intermediate flora, or BV were tested for production of sialidase, fucosidase, galactosidase, glucosaminidase, and glycine and arginine aminopeptidases.

RESULTS

Women with BV had higher frequencies and concentrations of bacteria producing mucin-degrading enzymes than did women with intermediate and normal flora (P < 0.001). Women with higher concentrations of bacteria producing mucin-degrading enzymes were more likely to have a thin discharge associated with BV (P < 0.001). The viscosity of diluted vaginal fluid samples from women with BV was significantly lower than those from women with normal flora (P = 0.001).

CONCLUSION

These data support the hypothesis that BV organisms degrade the protective mucus gel.

Determination of immunoglobulin A against Gardnerella vaginalis hemolysin, sialidase, and prolidase activities in vaginal fluid: implications for adverse pregnancy outcomes

A nested case-control study of low birth weight and preterm delivery was performed with singleton women. Immunoglobulin A (IgA) against the Gardnerella vaginalis hemolysin (anti-Gvh IgA) and sialidase and prolidase activities were determined in vaginal fluid at 17 weeks of gestation. Sialidase positivity and bacterial vaginosis with high prolidase activity were associated with 2- and 11-fold increased risks for low birth weight, respectively. No woman with bacterial vaginosis plus a strong anti-Gvh IgA response had an adverse outcome.

Vaginal hydrolytic enzymes, immunoglobulin A against Gardnerella vaginalis toxin, and risk of early preterm birth among women in preterm labor with bacterial vaginosis or intermediate flora

OBJECTIVE

The purpose of this study was to determine whether the microbial hydrolytic enzymes, sialidase and prolidase, and immunoglobulin A against the Gardnerella vaginalis cytolysin (anti-Gvh IgA) increase the risk for early preterm birth (< or =34 weeks of gestation) among women with bacterial vaginosis or intermediate flora.

STUDY DESIGN

Two hundred eighteen afebrile women in preterm labor with intact membranes had a vaginal Gram stain performed, and sialidase, prolidase, and anti-Gvh IgA concentrations were determined.

RESULTS

Women with bacterial vaginosis or intermediate flora had significantly higher sialidase and prolidase concentrations than women with normal flora. Among women with bacterial vaginosis or intermediate flora, the women with sialidase had a higher rate of early preterm birth (P =.05). Sialidase had a sensitivity of 43% and specificity of 77% for early preterm birth. Prolidase and anti-Gvh IgA did not predict early preterm birth.

CONCLUSION

Women in preterm labor with bacterial vaginosis or intermediate flora and detectable sialidase are at increased risk of early preterm birth.