Bacterial Vaginosis-associated Bacteria Research Articles

Host-vaginal microbiota interactions in the pathogenesis of bacterial vaginosis.

The cause of bacterial vaginosis, the most common cause of vaginal discharge in women, remains controversial. We recently published an updated conceptual model on bacterial vaginosis pathogenesis, focusing on the roles of Gardnerella vaginalis and Prevotella bivia as early colonizers and Atopobium vaginae and other bacterial vaginosis-associated bacteria (BVAB) as secondary colonizers in this infection. In this article, we extend the description of our model to include a discussion on the role of host-vaginal microbiota interactions in bacterial vaginosis pathogenesis. Although G. vaginalis and P. bivia are highly abundant in women with bacterial vaginosis, neither induce a robust inflammatory response from vaginal epithelial cells. These early colonizers may be evading the immune system while establishing the bacterial vaginosis biofilm. Secondary colonizers, including A. vaginae, Sneathia spp., and potentially other BVAB are more potent stimulators of the host-immune response to bacterial vaginosis and likely contribute to its signs and symptoms as well as its adverse outcomes. Elucidating the cause of bacterial vaginosis has important implications for diagnosis and treatment. Our current bacterial vaginosis pathogenesis model provides a framework for key elements that should be considered when designing and testing novel bacterial vaginosis diagnostics and therapeutics.

Dominance network analysis of the healthy human vaginal microbiome not dominated by Lactobacillus species

Although Lactobacillus dominance is one of the commonest characteristics of many healthy vaginal microbiomes, a significant proportion of healthy women lack an appreciable amount of Lactobacillus in their microbiome. Indeed, the vaginal microbiomes of many BV (bacterial vaginosis) patients lack the dominance by Lactobacillus. One would wonder what are special with those healthy non-Lactobacillus dominated vaginal microbiomes (nLDVM)? Here we re-analyzed the vaginal microbiome datasets of 1107 postpartum women in rural Malawi Doyle et al. (2018) using species dominance network (SDN) analysis. We discovered that: (i) The DN of the nLDVM is predominantly mutualistic, where most competitive (negative) relationships were from bacterial vaginosis-associated bacteria (BVAB), >60% occurred between BVAB and non-BVAB genera. Gardnerella was inhibited by a mutualistic combination of 23 genera, and Lactobacillus by 15 genera. These may be possible mechanisms by which the microbiome maintains high diversity but avoids dominance by Gardnerella or Lactobacillus. Gardnerella and Lactobacillus were only cooperated with a few genera, but they were positively connected with each other. The suppressed Lactobacillus species positively associated with Gardnerella was Lactobacillus iners, indicating that L. iners might act as an “enemy” in the Lactobacillus-poor vaginal microbiome, and inhibition of Gardnerella and L. iners might be a self-protective mechanism to maintain stability and health of this microbiome. (ii) We identified skeletons of the DNs and separate pathways consisting of high salience skeletons. Finegoldia species and Staphylococcus epidermidis were the hubs of the skeleton network. The roles that they play in the nLDVM deserve more attention of future studies.

The cervical microbiota in reproductive-age South African women with and without human papillomavirus infection

In this study we examined potential associations of HPV infection with the cervical microbiota. Cervical samples were collected from 87 HIV-seronegative reproductive-age Black South African women. Microbiota were characterized by Illumina sequencing of the V3-V4 hypervariable regions of the bacterial 16S rRNA gene. Thirty seven (42.5%) and 30 (34.5%) of the women had prevalent HPV and high-risk (HR)-HPV, respectively. Only 23 women (26.4%) had cervical microbiota dominated by a single Lactobacillus species (L. crispatus (2/87 (2.3%)), L. jensenii (2/87 (2.3%)), and L. iners (19/87 (21.8%)). The majority of the women (56/87 (64.4%)) had diverse cervical microbiota consisting of mainly bacterial vaginosis-associated bacteria. The remaining women (8/87 (9.2%)) had microbiota dominated by Aerococcus, Streptococcus, Chlamydia or Corynebacterium. Women with HR-HPV had significantly higher relative abundances of Aerococcaceae, Pseudomonadaceae and Bifidobacteriaceae compared to those with low-risk (LR)-HPV or no HPV-infection (LDA score >2.0, p < 0.05, q < 0.2). Gardnerella, Sneathia, and Atopobium were also found at greater relative abundances in HR-HPV-infected women compared to those with low-risk (LR)-HPV or no HPV-infection (LDA score >2.0, p < 0.05), although the difference was not significant after FDR-adjustment (q > 0.2). Further investigations of the bacterial taxa significantly enriched in HR-HPV-infected women are warranted.

Identification of bacterial vaginosis-associated bacteria in male urethra: Co-occurrence of Atopobium vaginae and Gardnerella vaginalis

Identification of bacterial vaginosis-associated bacteria in male urethra: Co-occurrence of Atopobium vaginae and Gardnerella vaginalis

Vaginal microbiome in early pregnancy and subsequent risk of spontaneous preterm birth: a case-control study.

To explore differences in the vaginal microbiome between preterm and term deliveries. Nested case-control study in 3D cohort (design, develop, discover). Quebec, Canada. Ninety-four women with spontaneous preterm birth as cases [17 early (<34 weeks) and 77 late (34-36 weeks) preterm birth] and 356 women as controls with term delivery (≥37 weeks). To assess the vaginal microbiome by sequencing the V4 region of the 16S ribosomal RNA (rRNA) gene in swabs self-collected during early pregnancy. Comparison of relative abundance of bacterial operational taxonomic units and oligotypes and identifying vaginal community state types (CSTs) in early or late spontaneous preterm and term deliveries. Lactobacillus gasseri/ Lactobacillus johnsonii (coefficient -5.36, 95% CI -8.07 to -2.65), Lactobacillus crispatus (99%)/ Lactobacillus acidophilus (99%) (-4.58, 95% CI -6.20 to -2.96), Lactobacillus iners (99%)/ Ralstonia solanacearum (99%) (-3.98, 95% CI -6.48 to -1.47) and Bifidobacterium longum/ Bifidobacterium breve (-8.84, 95% CI -12.96 to -4.73) were associated with decreased risk of early but not late preterm birth. Six vaginal CSTs were identified: four dominated by Lactobacillus; one with presence of bacterial vaginosis-associated bacteria (Gardnerella vaginalis, Atopobium vaginae and Veillonellaceae bacterium) (CST IV); and one with nondominance of Lactobacillus (CST VI). CST IV was associated with increased risk of early (4.22, 95% CI 1.24-24.85) but not late (1.63, 95% CI 0.68-5.04) preterm birth, compared with CST VI. Lactobacillus gasseri/L. johnsonii, L. crispatus/L. acidophilus, L. iners/R. solanacearum and B. longum/B. breve may be associated with decreased risk of early preterm birth. A bacterial vaginosis-related vaginal CST versus a CST nondominated by Lactobacillus may be associated with increased risk of early preterm birth. Largest study of its kind finds certain species of vaginal Lactobacillus + Bifidobacterium may relate to lower risk of preterm birth.

Microbial Composition Predicts Genital Tract Inflammation and Persistent Bacterial Vaginosis in South African Adolescent Females.

Young African females are at an increased risk of HIV acquisition, and genital inflammation or the vaginal microbiome may contribute to this risk. We studied these factors in 168 HIV-negative South African adolescent females aged 16 to 22 years. Unsupervised clustering of 16S rRNA gene sequences revealed three clusters (subtypes), one of which was strongly associated with genital inflammation. In a multivariate model, the microbiome compositional subtype and hormonal contraception were significantly associated with genital inflammation. We identified 40 taxa significantly associated with inflammation, including those reported previously (Prevotella, Sneathia, Aerococcus, Fusobacterium, and Gemella) as well as several novel taxa (including increased frequencies of bacterial vaginosis-associated bacterium 1 [BVAB1], BVAB2, BVAB3, Prevotella amnii, Prevotella pallens, Parvimonas micra, Megasphaera, Gardnerella vaginalis, and Atopobium vaginae and decreased frequencies of Lactobacillus reuteri, Lactobacillus crispatus, Lactobacillus jensenii, and Lactobacillus iners). Women with inflammation-associated microbiomes had significantly higher body mass indices and lower levels of endogenous estradiol and luteinizing hormone. Community functional profiling revealed three distinct vaginal microbiome subtypes, one of which was characterized by extreme genital inflammation and persistent bacterial vaginosis (BV); this subtype could be predicted with high specificity and sensitivity based on the Nugent score (≥9) or BVAB1 abundance. We propose that women with this BVAB1-dominated subtype may have chronic genital inflammation due to persistent BV, which may place them at a particularly high risk for HIV infection.

Generation of dimeric single-chain antibodies neutralizing the cytolytic activity of vaginolysin

Background: Gardnerella vaginalis is a bacterial vaginosis-associated vaginal bacterium, which produces toxin vaginolysin (VLY). VLY is a pore-forming toxin suggested to be the main virulence factor of G. vaginalis. The high recurrence rate of BV and emergence of antibiotic-resistant bacterial species demonstrate the need for development of recombinant antibodies as novel therapeutic agents for disease treatment. Single-chain variable fragments (scFvs) generated against VLY exhibited reduced efficacy to neutralize VLY activity compared to the respective full-length antibodies. To improve properties of scFvs the monospecific dimeric scFvs were generated by a genetic fusion of two anti-VLY scFv molecules connected with the alpha-helix-forming peptide linker. Results: N-terminally hexahistidine-tagged d imeric scFvs were constructed, produced in Escherichia coli and purified using metal-chelate affinity chromatography. Inhibition of VLY-mediated human erythrocyte lysis by dimeric and monomeric scFvs was detected by the in vitro hemolytic assay. Circulating half-life of purified scFvs in blood plasma of mice was accessed using ELISA. Dimeric anti-VLY scFvs showed higher neutralizing potency and extended circulating half-life in comparison with parental monomeric scFv. Conclusions: The protein obtained by a genetic fusion of two anti-VLY scFvs into dimeric molecule exhibited increased properties in comparison with monomeric scFv. This new recombinant antibody might implement new possibilities for the prophylaxis and treatment of the diseases caused by bacteria G. vaginalis . Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabla normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Calibri,sans-serif; mso-bidi-font-family:Times New Roman;}

Advances in the Understanding and Treatment of Male Urethritis.

Neisseria gonorrhoeae and Chlamydia trachomatis are well-documented urethral pathogens, and the literature supporting Mycoplasma genitalium as an etiology of urethritis is growing. Trichomonas vaginalis and viral pathogens (herpes simplex virus types 1 and 2 and adenovirus) can cause urethritis, particularly in specific subpopulations. New data are emerging regarding the potential role of bacterial vaginosis-associated bacteria in urethritis, although results are inconsistent regarding the pathogenic role of Ureaplasma urealyticum in men. Mycoplasma hominis and Ureaplasma parvum do not appear to be pathogens. Men with suspected urethritis should undergo evaluation to confirm urethral inflammation and etiologic cause. Although nucleic acid amplification testing would detect N. gonorrhoeae and C. trachomatis (or T. vaginalis if utilized), there is no US Food and Drug Administration-approved clinical test for M. genitalium available in the United States at this time. The varied etiologies of urethritis and lack of diagnostic options for some organisms present treatment challenges in the clinical setting.

Longitudinal analysis reveals characteristically high proportions of bacterial vaginosis-associated bacteria and temporal variability of vaginal microbiota in northern pig-tailed macaques (Macaca leonina).

The complex and dynamic vaginal microbial ecosystem is critical to both health and disease of the host. Studies focusing on how vaginal microbiota influences HIV-1 infection may face limitations in selecting proper animal models. Given that northern pig-tailed macaques (Macaca leonina) are susceptible to HIV-1 infection, they may be an optimal animal model for elucidating the mechanisms by which vaginal microbiota contributes to resistance and susceptibility to HIV-1 infection. However, little is known about the composition and temporal variability of vaginal microbiota of the northern pig-tailed macaque. Here, we present a comprehensive catalog of the composition and temporal dynamics of vaginal microbiota of two healthy northern pig-tailed macaques over 19 weeks using 454-pyrosequencing of 16S rRNA genes. We found remarkably high proportions of a diverse array of anaerobic bacteria associated with bacterial vaginosis. Atopobium and Sneathia were dominant genera, and interestingly, we demonstrated the presence of Lactobacillus-dominated vaginal microbiota. Moreover, longitudinal analysis demonstrated that the temporal dynamics of the vaginal microbiota were considerably individualized. Finally, network analysis revealed that vaginal pH may influence the temporal dynamics of the vaginal microbiota, suggesting that inter-subject variability of vaginal bacterial communities could be mirrored in inter-subject variation in correlation profiles of species with each other and with vaginal pH over time. Our results suggest that the northern pig-tailed macaque could be an ideal animal model for prospective investigation of the mechanisms by which vaginal microbiota influence susceptibility and resistance to HIV-1 infection in the context of highly polymicrobial and Lactobacillus-dominated states.

HIV-Enhancing Factors Are Secreted by Reproductive Epithelia upon Inoculation with Bacterial Vaginosis-Associated Bacteria.

Bacterial vaginosis is a common reproductive infection in which commensal vaginal lactobacilli are displaced by a mixed population of pathogenic bacteria. Bacterial vaginosis increases susceptibility to HIV, and it has been suggested that host innate immune responses to pathogenic bacteria contribute to enhanced infection, yet the cellular mechanisms mediating the increased HIV susceptibility remain uncharacterized. We evaluated the HIV-enhancing effects of bacterial vaginosis by inoculating endocervical epithelia with Atopobium vaginae, a bacterial vaginosis-associated bacteria, and assaying secreted factors for HIV-enhancing activity. When epithelia and A. vaginae were cocultured, we observed increased HIV-enhancing activity mediated by secreted low molecular weight factors. From this complex mixture we identified several upregulated host proteins, which functioned in combination to enhance HIV infection. These studies suggest that the host immune response to bacterial vaginosis-associated bacteria results in the release of HIV-enhancing factors. The combined activity of bacterial vaginosis-induced proteins likely mediates HIV enhancement.

Relationship of Selected Bacterial Vaginosis-associated Bacteria to Nugent Score Bacterial Vaginosis Among Urban Women Early in Pregnancy

Relationship of Selected Bacterial Vaginosis-associated Bacteria to Nugent Score Bacterial Vaginosis Among Urban Women Early in Pregnancy

Bacterial Vaginosis Diagnosed by Analysis of First-Void-Urine Specimens

Bacterial vaginosis (BV) is traditionally diagnosed using vaginal samples. The aim of this study was to investigate whether BV can be diagnosed from first-void urine (FVU). Self-collected vaginal smears, vaginal swabs, and FVU were obtained from 176 women. BV was diagnosed by Nugent's criteria. The FVU and vaginal swabs were analyzed by quantitative PCRs (qPCRs) for selected vaginal bacteria (Atopobium vaginae, Prevotella spp., Gardnerella vaginalis, bacterial vaginosis-associated bacterium 2, Eggerthella-like bacterium, "Leptotrichia amnionii," Megasphaera type 1), and all had an area under the receiver operating characteristic (ROC) curve of >85%, suggesting good prediction of BV according to the Nugent score. All seven bacteria in FVU were significantly associated with BV in univariate analysis. An accurate diagnosis of BV from urine was obtained in this population by a combination of qPCRs for Megasphaera type 1 and Prevotella spp. The same two bacteria remained significantly associated with BV in a multivariate model after adjusting for the other five species. There was no statistically significant difference between the sensitivities and specificities of BV diagnosis by molecular methods performed on swabs and FVU samples. A linear regression analysis showed good agreement between bacterial loads from swabs and FVU, but Prevotella spp. could be detected in high numbers in a few FVU samples without being present in swabs. This method will allow diagnosis of BV in studies where only urine has been collected and where detection of BV is considered relevant.

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

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). 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. 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). 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.

Relationship of selected bacterial vaginosis-associated bacteria to Nugent score bacterial vaginosis among urban women early in pregnancy.

Among urban, primarily African American pregnant women, 74% were identified with Nugent score bacterial vaginosis (BV). All BV-associated bacteria were more prevalent among women with Nugent score BV. Bacterial vaginosis-associated bacteria 3 (BVAB3) had the highest positive predictive value, whereas Gardnerella vaginalis and Atopobium spp. had the highest sensitivity. Atopobium spp. levels had the most significant area under the curve.

O14.1 Bacterial Vaginosis-Associated Bacteria (BVAB) and Non-Gonococcal Urethritis (NGU)

BackgroundTraditional cultivation approaches have not identified additional pathogens responsible for the 45% of non-gonococcal urethritis (NGU) cases with no identified aetiology. Cultivation-independent methods have identified novel bacteria associated with female...

P1.029 Bacterial Vaginosis Associated Bacteria Are Detected Together with Ureaplasmas in Men But Not Associated with Non-Gonococcal Urethritis

BackgroundLittle is known about the presence of bacterial vaginosis (BV) associated bacteria in men, but male partners of women with BV have been reported to have a high risk of...

Interaction Between Lactobacilli, Bacterial Vaginosis-Associated Bacteria, and HIV Type 1 RNA and DNA Genital Shedding in U.S. and Kenyan Women

Bacterial vaginosis has been associated with genital HIV-1 shedding; however, the effect of specific vaginal bacterial species has not been assessed. We tested cervicovaginal lavage from HIV-1-seropositive women for common Lactobacillus species: L. crispatus, L. jensenii, and seven BV-associated species: BVAB1, BVAB2, BVAB3, Leptotrichia, Sneathia, Megasphaera, and Atopobium spp. using quantitative PCR. We used linear and Poisson regression to evaluate associations between vaginal bacteria and genital HIV-1 RNA and DNA. Specimens from 54 U.S. (310 visits) and 50 Kenyan women (137 visits) were evaluated. Controlling for plasma viral load, U.S. and Kenyan women had similar rates of HIV-1 RNA (19% of visits vs. 24%; IRR=0.95; 95% CI 0.61, 1.49) and DNA shedding (79% vs. 76%; IRR=0.90; 0.78, 1.05). At visits during antiretroviral therapy (ART), the likelihood of detection of HIV-1 RNA shedding was greater with BVAB3 (IRR=3.16; 95% CI 1.36, 7.32), Leptotrichia, or Sneathia (IRR=2.13; 1.02, 4.72), and less with L. jensenii (IRR=0.39; 0.18, 0.84). At visits without ART, only L. crispatus was associated with a lower likelihood of HIV-1 RNA detection (IRR=0.6; 0.40, 0.91). Vaginal Lactobacillus species were associated with lower risk of genital HIV-1 shedding, while the presence of certain BV-associated species may increase that risk.

Development and Validation of a Semiquantitative, Multitarget PCR Assay for Diagnosis of Bacterial Vaginosis

Quantitative PCR assays were developed for 4 organisms reported previously to be useful positive indicators for the diagnosis of bacterial vaginosis (BV)--Atopobium vaginae, Bacterial Vaginosis-Associated Bacterium 2 (BVAB-2), Gardnerella vaginalis, and Megasphaera-1--and a single organism (Lactobacillus crispatus) that has been implicated as a negative indicator for BV. Vaginal samples (n = 169), classified as positive (n = 108) or negative (n = 61) for BV based on a combination of the Nugent Gram stain score and Amsel clinical criteria, were analyzed for the presence and quantity of each of the marker organisms, and the results were used to construct a semiquantitative, multiplex PCR assay for BV based on detection of 3 positive indicator organisms (A. vaginae, BVAB-2, and Megasphaera-1) and classification of samples using a combinatorial scoring system. The prototype BV PCR assay was then used to analyze the 169-member developmental sample set and, in a prospective, blinded manner, an additional 227 BV-classified vaginal samples (110 BV-positive samples and 117 BV-negative samples). The BV PCR assay demonstrated a sensitivity of 96.7% (202/209), a specificity of 92.2% (153/166), a positive predictive value of 94.0%, and a negative predictive value of 95.6%, with 21 samples (5.3%) classified as indeterminate for BV. This assay provides a reproducible and objective means of evaluating critical components of the vaginal microflora in women with signs and symptoms of vaginitis and is comparable in diagnostic accuracy to the conventional gold standard for diagnosis of BV.

Is there a correlation between bacterial vaginosis and preterm labour in women in the Otago region of New Zealand?

While an association between bacterial vaginosis and preterm labour has been established, the relative contribution of this condition remains controversial. To determine whether bacterial vaginosis is likely to be an important contributing factor in preterm births in Otago, New Zealand, a region with a historically high rate of such births. Women receiving antenatal care from Queen Mary Maternity Services were studied prospectively. Cases were women presenting with preterm labour or premature rupture of membranes. Controls had uncomplicated pregnancies and delivered at term. Vaginal swabs from 44 cases and 72 controls were examined by amplification of bacterial 16S rRNA genes followed by denaturing gel gradient electrophoresis. Atopobium vaginae, a bacterial vaginosis-associated bacterium, was detected in a separate polymerase chain reaction. Nugent Gram stain scoring of vaginal swabs from 44 cases and 69 controls was also carried out. Denaturing gel gradient electrophoresis revealed three major types of band profiles corresponding to normal, intermediate and bacterial vaginosis microflorae. There were significantly more cases with bacterial vaginosis band profiles compared with controls (P = 0.024). More cases had intermediate or bacterial vaginosis Nugent scores compared with controls (P = 0.022). Conversely, controls were more likely to have normal scores than cases (P = 0.022). Atopobium vaginae was equally distributed between the cases and controls. Women in the Otago region undergoing preterm labour were approximately twice as likely to have a bacterial vaginosis type vaginal microflora as controls. In preterm labour, the incidence of bacterial vaginosis was comparable with that found elsewhere, suggesting that current guidelines for treatment and detection of this condition are appropriate.

Comparison of oral and vaginal metronidazole for treatment of bacterial vaginosis in pregnancy: impact on fastidious bacteria

BackgroundBacterial vaginosis (BV) is a common condition that is associated with preterm birth and acquisition of complex communities of vaginal bacteria that include several fastidious species. Treatment of BV in pregnancy has mixed effects on the risk of preterm delivery, which some hypothesize is due to variable antibiotic efficacy for the fastidious bacteria. Both oral and intravaginal metronidazole can be used to treat bacterial vaginosis in pregnancy, but little is known about the impact of different routes of antibiotic administration on concentrations of fastidious vaginal bacteria.MethodsThis was a sub-study of a larger randomized trial of oral versus vaginal metronidazole for treatment of BV in pregnancy. Fifty-three women were evaluated, including 30 women who received oral metronidazole and 23 who received intravaginal metronidazole. Bacterial taxon-specific quantitative PCR assays were used to measure concentrations of bacterial vaginosis associated bacterium (BVAB) 1, 2, and 3, Gardnerella vaginalis, Atopobium species, Leptotrichia/Sneathia species, Megasphaera species, and Lactobacillus crispatus before and after antibiotic treatment.ResultsConcentrations of Leptotrichia and Sneathia spp. and the fastidious Clostridia-like bacterium designated BVAB1 decreased significantly with oral (p = .002, p = .02) but not vaginal therapy (p = .141, p = .126). The fastidious bacterium BVAB3 did not significantly decrease with either treatment. Concentrations of Atopobium spp., reportedly resistant to metronidazole in vitro, dropped significantly with oral (p = .002) and vaginal (p = .001) treatment. There was no significant difference in the magnitude of change in bacterial concentrations between oral and vaginal treatment arms for any of the bacterial species. Lactobacillus crispatus concentrations did not change.ConclusionBoth oral and vaginal metronidazole therapy in pregnant women result in a significant decrease in concentrations of most BV-associated anaerobic bacteria, with the exception that Leptotrichia, Sneathia and BVAB1 do not significantly decrease with vaginal metronidazole therapy. These data suggest that the route of antibiotic administration has a minor impact on bacterial eradication in pregnant women with BV.Trail RegistrationThis trial is registered with ClinicalTrials.gov, number NCT00153517