Genetic Variation in Toll-Like Receptor 5 and Colonization with Flagellated Bacterial Vaginosis-Associated Bacteria.

Bacterial vaginosis (BV) is a vaginal dysbiotic condition linked to negative gynecological and reproductive sequelae. Flagellated bacteria have been identified in women with BV, including Mobiluncus spp. and BV-associated bacterium-1 (BVAB1), an uncultivated, putatively flagellated species. The host response to flagellin mediated through Toll-like receptor 5 (TLR5) has not been explored in BV. Using independent discovery and validation cohorts, we examined the hypothesis that TLR5 deficiency-defined by a dominant negative stop codon polymorphism, rs5744168-is associated with an increased risk for BV and increased colonization with flagellated bacteria associated with BV (BVAB1, Mobiluncus curtisii, and Mobiluncus mulieris). TLR5 deficiency was not associated with BV status, and TLR5-deficient women had decreased colonization with BVAB1 in both cohorts. We stimulated HEK-hTLR5-overexpressing NF-κB reporter cells with whole, heat-killed M. mulieris or M. curtisii and with partially purified flagellin from these species; as BVAB1 is uncultivated, we used cervicovaginal lavage (CVL) fluid supernatant from women colonized with BVAB1 for stimulation. While heat-killed M. mulieris and CVL fluid from women colonized with BVAB1 stimulate a TLR5-mediated response, heat-killed M. curtisii did not. In contrast, partially purified flagellin from both Mobiluncus species stimulated a TLR5-mediated response in vitro We observed no correlation between vaginal interleukin 8 (IL-8) and flagellated BVAB concentrations among TLR5-sufficient women. Interspecies variation in accessibility of flagellin recognition domains may be responsible for these observations, as reflected in the potentially novel flagellin products encoded by Mobiluncus species versus those encoded by BVAB1.

Structure determination of CAMP factor of Mobiluncus curtisii and insights into structural dynamics.

Bacterial vaginosis (BV) is a common type of vaginal inflammation caused by a proliferation of pathogenic bacteria, among which Mobiluncus curtisii. In our previous studies on M. curtisii genome, we identified the presence of a genomic fragment encoding a 25 kDa pore-forming toxin, the CAMP factor, which is known to be involved in the synergistic lysis of erythrocytes namely CAMP reaction. However, whether this hypothetical gene product has hemolytic activity is unknown. Moreover, its relative structure and function are not yet solved. Here we found that the M. curtisii CAMP factor is a monomer at pH 4.4 and oligomer at pH > 4.6. Hemolysis assays showed that M. curtisii CAMP factor could lyse sheep red blood cells efficiently in pH 5.4-7.4. Negative staining electron microscope analysis of the CAMP factor revealed ring-like structures at pH above 4.6. Additionally, the crystal structure of M. curtisii CAMP factor, determineded at 1.85 Å resolution, reveals a 5 + 3 helix motif. Further functional analysis suggested that the structural rearrangement of the N-terminal domain might be required for protein function. In conclusion, this structure-function relationship study of CAMP factor provides a new perspective of the M. curtisii role in BV development.

Establishment of a sensitive system for analysis of human vaginal microbiota on the basis of rRNA-targeted reverse transcription-quantitative PCR.

Ten specific primer sets, for Lactobacillus gasseri, Lactobacillus crispatus, Atopobium vaginae, Gardnerella vaginalis, Mobiluncus curtisii, Chlamydia trachomatis/muridarum, Bifidobacterium longum subsp. longum, Bifidobacterium longum subsp. infantis, Bifidobacterium adolescentis, and Bifidobacterium angulatum, were developed for quantitative analysis of vaginal microbiota. rRNA-targeted reverse transcription-quantitative PCR (RT-qPCR) analysis of the vaginal samples from 12 healthy Japanese volunteers using the new primer sets together with 25 existing primer sets revealed the diversity of their vaginal microbiota: Lactobacilli such as L. crispatus, L. gasseri, Lactobacillus jensenii, Lactobacillus iners, and Lactobacillus vaginalis, as the major populations at 10(7) cells/ml vaginal fluid, were followed by facultative anaerobes such as Streptococcus and strict anaerobes at lower population levels of 10(4) cells/ml or less. Certain bacterial vaginosis (BV)-related bacteria, such as G. vaginalis, A. vaginae, M. curtisii, and Prevotella, were also detected in some subjects. Especially in one subject, both G. vaginalis and A. vaginae were detected at high population levels of 10(8.8) and 10(8.9) cells/ml vaginal fluid, suggesting that she is an asymptomatic BV patient. These results suggest that the RT-qPCR system is effective for accurate analysis of major vaginal commensals and diagnosis of several vaginal infections.

Association between BVAB1 and high Nugent scores among women with bacterial vaginosis.

As part of a larger study using 454 pyrosequencing to investigate the vaginal microbiota of women with bacterial vaginosis (BV), we found an association between a novel BV-associated bacterium (BVAB1) and high Nugent scores and propose that BVAB1 is the curved Gram-negative rod traditionally identified as Mobiluncus spp. in vaginal Gram stains.

Mycoplasma, bacterial vaginosis-associated bacteria BVAB3, race, and risk of preterm birth in a high-risk cohort.

OBJECTIVE: Genital tract infection accounts for approximately 25-40% of all preterm births. We sought to assess the relationship between preterm birth and selected vaginal bacterial taxa associated with preterm birth either directly or through their association with bacterial vaginosis (BV). STUDY DESIGN: Vaginal fluid for Gram stain was collected between 17 and 22 weeks' gestation as part of a randomized trial of ultrasound-indicated cerclage for preterm birth prevention in women at high risk for recurrent spontaneous preterm birth. Bacterial deoxyribonucleic acid was extracted from the Gram stain slides and analyzed using quantitative polymerase chain reaction. RESULTS: Among the 499 participants, Mycoplasma was positively correlated with increased risk of preterm (risk ratio [RR], 1.83; 95% confidence interval [CI], 1.52-2.22) as was Mobiluncus (RR, 1.36; 95% CI, 1.07-1.73) and Atopobium (RR, 1.44; 95% CI, 1.1-1.87). However, there were strong interactions between the race/ethnic group and the presence of these and other individual taxa on risk of preterm birth. By contrast, bacterial vaginosis-associated bacteria (BVAB)-3 was consistently associated with a reduction in the risk of preterm birth for all racial/ethnic groups (0.55; 95% CI, 0.39-0.78). CONCLUSION: BV is characterized by a reduction of Lactobacillus, and lactic acid-producing bacteria and the presence of Mobiluncus; we found these factors and the presence of Mycoplasma to be associated with an increased risk of preterm birth. By contrast, the presence of a recently identified organism sufficient to cause BV, BVAB3, decreased the risk of preterm birth. These findings give insight into why treating BV has mixed impact on risk of preterm birth.

More than meets the eye: associations of vaginal bacteria with gram stain morphotypes using molecular phylogenetic analysis.

Bacterial vaginosis (BV) is a highly prevalent condition associated with adverse health outcomes. Gram stain analysis of vaginal fluid is the standard for confirming the diagnosis of BV, wherein abundances of key bacterial morphotypes are assessed. These Lactobacillus, Gardnerella, Bacteroides, and Mobiluncus morphotypes were originally linked to particular bacterial species through cultivation studies, but no studies have systematically investigated associations between uncultivated bacteria detected by molecular methods and Gram stain findings. In this study, 16S-rRNA PCR/pyrosequencing was used to examine associations between vaginal bacteria and bacterial morphotypes in 220 women with and without BV. Species-specific quantitative PCR (qPCR) and fluorescence in Situ hybridization (FISH) methods were used to document concentrations of two bacteria with curved rod morphologies: Mobiluncus and the fastidious BV-associated bacterium-1 (BVAB1). Rank abundance of vaginal bacteria in samples with evidence of curved gram-negative rods showed that BVAB1 was dominant (26.1%), while Mobiluncus was rare (0.2% of sequence reads). BVAB1 sequence reads were associated with Mobiluncus morphotypes (p<0.001). Among women with curved rods, mean concentration of BVAB1 DNA was 2 log units greater than Mobiluncus (p<0.001) using species-specific quantitative PCR. FISH analyses revealed that mean number of BVAB1 cells was 2 log units greater than Mobiluncus cells in women with highest Nugent score (p<0.001). Prevotella and Porphyromonas spp. were significantly associated with the "Bacteroides morphotype," whereas Bacteroides species were rare. Gram-negative rods designated Mobiluncus morphotypes on Gram stain are more likely BVAB1. These findings provide a clearer picture of the bacteria associated with morphotypes on vaginal Gram stain.

A multi-omic systems-based approach reveals metabolic markers of bacterial vaginosis and insight into the disease.

BACKGROUND: Bacterial vaginosis (BV) is the most common vaginal disorder of reproductive-age women. Yet the cause of BV has not been established. To uncover key determinants of BV, we employed a multi-omic, systems-biology approach, including both deep 16S rRNA gene-based sequencing and metabolomics of lavage samples from 36 women. These women varied demographically, behaviorally, and in terms of health status and symptoms. PRINCIPAL FINDINGS: 16S rRNA gene-based community composition profiles reflected Nugent scores, but not Amsel criteria. In contrast, metabolomic profiles were markedly more concordant with Amsel criteria. Metabolomic profiles revealed two distinct symptomatic BV types (SBVI and SBVII) with similar characteristics that indicated disruption of epithelial integrity, but each type was correlated to the presence of different microbial taxa and metabolites, as well as to different host behaviors. The characteristic odor associated with BV was linked to increases in putrescine and cadaverine, which were both linked to Dialister spp. Additional correlations were seen with the presence of discharge, 2-methyl-2-hydroxybutanoic acid, and Mobiluncus spp., and with pain, diethylene glycol and Gardnerella spp. CONCLUSIONS: The results not only provide useful diagnostic biomarkers, but also may ultimately provide much needed insight into the determinants of BV.

Gram stains: a resource for retrospective analysis of bacterial pathogens in clinical studies.

We demonstrate the feasibility of using qPCR on DNA extracted from vaginal Gram stain slides to estimate the presence and relative abundance of specific bacterial pathogens. We first tested Gram stained slides spiked with a mix of 10(8) cfu/ml of Escherichia coli and 10(5) cfu/ml of Lactobacillus acidophilus. Primers were designed for amplification of total and species-specific bacterial DNA based on 16S ribosomal gene regions. Sample DNA was pre-amplified with nearly full length 16S rDNA ribosomal gene fragment, followed by quantitative PCR with genera and species-specific 16S rDNA primers. Pre-amplification PCR increased the bacterial amounts; relative proportions of Escherichia coli and Lactobacillus recovered from spiked slides remained unchanged. We applied this method to forty two archived Gram stained slides available from a clinical trial of cerclage in pregnant women at high risk of preterm birth. We found a high correlation between Nugent scores based on bacterial morphology of Lactobacillus, Gardenerella and Mobiluncus and amounts of quantitative PCR estimated genus specific DNA (rrn copies) from Gram stained slides. Testing of a convenience sample of eight paired vaginal swabs and Gram stains freshly collected from healthy women found similar qPCR generated estimates of Lactobacillus proportions from Gram stained slides and vaginal swabs. Archived Gram stained slides collected from large scale epidemiologic and clinical studies represent a valuable, untapped resource for research on the composition of bacterial communities that colonize human mucosal surfaces.

Molecular quantification of Gardnerella vaginalis and Atopobium vaginae loads to predict bacterial vaginosis.

BACKGROUND: Bacterial vaginosis (BV) is a poorly detected public health problem that is associated with preterm delivery and for which no reliable diagnostic tool exists. METHODS: Molecular analysis of 231 vaginal samples, classified by Gram stain-based Nugent score, was used to propose molecular criteria for BV; these criteria were prospectively applied to 56 new samples. A quantitative molecular tool targeting 8 BV-related microorganisms and a human gene was developed using a specific real-time polymerase chain reaction assay and serial dilutions of a plasmid suspension. The targeted microorganisms were Gardnerella vaginalis, Lactobacillus species, Mobiluncus curtisii, Mobiluncus mulieris, and Candida albicans (which can be identified by Gram staining), as well as Atopobium vaginae, Mycoplasma hominis, and Ureaplasma urealyticum (which cannot be detected by Gram staining). RESULTS: With use of the Nugent score, 167 samples were classified as normal, 20 were classified as BV, and 44 were classified as intermediate. Except for U. urealyticum, M. mulieris, and Lactobacillus species, DNA of the tested bacteria was detected more frequently in samples demonstrating BV, but the predictive value of such detection was low. The molecular quantification of A. vaginae (DNA level, > or = 10(8) copies/mL) and G. vaginalis (DNA level, > or = 10(9) copies/mL) had the highest predictive value for the diagnosis of BV, with excellent sensitivity (95%), specificity (99%), and positive (95%) and negative (99%) predictive values; 25 (57%) of the samples demonstrating intermediate flora had a BV profile. When applied prospectively, our molecular criteria had total positive and negative predictive values of 96% and 99%, respectively. CONCLUSIONS: We report a highly reproducible, quantitative tool to objectively analyze vaginal flora that uses cutoff values for the concentrations of A. vaginae and G. vaginalis to establish the molecular diagnosis of BV.

[Detection of Mobiluncus species by special primer amplification and 16S DNA sequence analysis].

Bacterial Vaginosis (BV), a microecological disease leaded by overgrowth of the vaginal bacteria, is one of the Polymicrobial Diseases. The close relationship between BV and Mobiluncus ssp. was recognized gradually. But it is difficult to get the pure culture of this anaerobic bacterium because of its rigorous requirement for growth conditions. The vaginal discharge came from the BV animal model--Rhesus monkey was cultured in anaerobic environment. The 16S rRNA gene was amplified and sequenced using mobiluncus-specific primers. Mobiluncus ssp, closely related to Mobiluncus mulieris, were detected, by comparing with the 16S rRNA genes in the GenBank.

Transfer of members of the genus Falcivibrio to the genus Mobiluncus, and emended description of the genus Mobiluncus.

It has long been thought that the genera Mobiluncus and Falcivibrio contain the same organisms. Using a polyphasic approach, it was found that Mobiluncus curtisii and Mobiluncus mulieris were the same as Falcivibrio vaginalis and Falcivibrio grandis, respectively. As the genus name Mobiluncus takes precedence, it is proposed that F. vaginalis and F. grandis be transferred to the genus Mobiluncus. In agreement with previous studies, results from phenotypic tests did not support the separation of M. curtisii strains into its two subspecies, M. curtisii subsp. curtisii and M. curtisii subsp. holmesii. Phenotypic complexity within M. curtisii dictates that the species should be treated as a complex until more in-depth analyses of the species have been performed. Phylogenetic analyses, based on 16S rRNA gene sequences, demonstrated that the genus Mobiluncus was associated with Varibaculum cambriense and the two subspecies of Actinomyces neuii, and that A. neuii is only distantly related to Actinomyces sensu stricto.

Prevalence of Mobiluncus spp among women with and without bacterial vaginosis as detected by polymerase chain reaction.

BACKGROUND: Mobiluncus spp are highly associated with bacterial vaginosis, but their role in its pathogenesis is unknown. The authors used polymerase chain reaction (PCR) to compare the prevalence of Mobiluncus in women with and without bacterial vaginosis. GOAL: To compare the prevalence of Mobiluncus spp among women with and without bacterial vaginosis and to compare the sensitivities of PCR and Gram stain for detection. STUDY DESIGN: Vaginal specimens from 74 women were analyzed by PCR and Gram stain for the presence of Mobiluncus spp. Comparisons were made between the prevalence of this organism between the two cohorts and between the Gram stain and PCR detection methods. RESULTS: Mobiluncus was detected by PCR in 84.5% of women with bacterial vaginosis and in 38% of women without infection. M curtisii was rarely detected in the latter group, though it was found in 65.3% of women with bacterial vaginosis. The sensitivity and specificity of Gram stain compared with PCR were 46.9% and 100%, respectively. CONCLUSIONS: Mobiluncus is more common in healthy women than previously suspected, with M mulieris as the predominant species. The significant difference in the prevalence of M curtisii between women with bacterial vaginosis and uninfected women suggests that this species could be involved in the pathogenesis of bacterial vaginosis.

Classification of the genus Mobiluncus based on comparative partial 16S rRNA gene analysis.

On the basis of partial 16S rRNA gene sequences and the results of Southern blot analyses, we confirmed the division of the genus Mobiluncus into the species Mobiluncus curtisii and Mobiluncus mulieris. Division of M. curtisii into M. curtisii subsp. curtisii and M. curtisii subsp. holmesii was not supported by our data.

Broad-range PCR amplification and DNA sequence analysis reveals variable motifs in 16S rRNA genes of Mobiluncus species.

Using DNA primers based on highly conserved regions of bacterial 16S ribosomal RNA genes, a technique was established for detection of Mobiluncus species by polymerase chain reaction (PCR) and hybridization analysis. Part of the 16S rRNA genes of Mobiluncus mulieris, Mobiluncus curtisii and uncharacterized Mobiluncus strains were analyzed by broad-range PCR amplification and direct DNA sequencing analysis. Sequence comparison of the partial 16S rRNA genes of Mobiluncus curtisii, Mobiluncus mulieris and atypical Mobiluncus strains studied indicated genus and species-specific motifs within the variable regions V3, V4 and V9 of 16S ribosomal DNAs. A Mobiluncus curtisii-specific primer, located within the variable region V3 of the 16S rRNA gene, was designed for Southern blot hybridization analysis of broad-range PCR products. Broad-range amplification combined with a M. curtisii-specific hybridization probe, Mob V3, distinguished between Mobiluncus curtisii, Mobiluncus mulieris, and atypical Mobiluncus strains.