Penile Microbiota and Female Partner Bacterial Vaginosis in Rakai, Uganda

Bacterial vaginosis (BV) is a common vaginal bacterial imbalance associated with risk for HIV and poor gynecologic and obstetric outcomes. Male circumcision reduces BV-associated bacteria on the penis and decreases BV in female partners, but the link between penile microbiota and female partner BV is not well understood. We tested the hypothesis that having a female partner with BV increases BV-associated bacteria in uncircumcised men. We characterized penile microbiota composition and density (i.e., the quantity of bacteria per swab) by broad-coverage 16S rRNA gene-based sequencing and quantitative PCR (qPCR) in 165 uncircumcised men from Rakai, Uganda. Associations between penile community state types (CSTs) and female partner's Nugent score were assessed. We found seven distinct penile CSTs of increasing density (CST1 to 7). CST1 to 3 and CST4 to 7 were the two major CST groups. CST4 to 7 had higher prevalence and abundance of BV-associated bacteria, such as Mobiluncus and Dialister, than CST1 to 3. Men with CST4 to 7 were significantly more likely to have a female partner with a high Nugent score (P = 0.03). Men with two or more extramarital partners were significantly more likely to have CST4 to 7 than men with only marital partners (CST4 to 7 prevalence ratio, 1.84; 95% confidence interval [CI], 1.16 to 2.92). Female partner Nugent BV is significantly associated with penile microbiota. Our data support the exchange of BV-associated bacteria through intercourse, which may explain BV recurrence and persistence.

IMPORTANCE

Bacterial vaginosis (BV) is sexually associated but not considered a sexually transmitted disease. Our findings suggest that the uncircumcised penis is an important niche for BV-associated genital anaerobes. In addition, we found a link between extramarital sexual relationships and BV-associated bacteria in men, which parallels earlier findings of the association between sexual activity and BV in women. This suggests the sexual transmissibility of BV-associated bacteria. Reducing bacterial exchange by barrier methods and managing carriage of BV-associated bacteria in men may decrease BV persistence and recurrence in women.

Smoking in women with chronic vaginal discomfort is not associated with decreased abundance of Lactobacillus spp. but promotes Mobiluncus and Gardnerella spp. overgrowth - secondary analysis of trial data including microbio-me analysis

BACKGROUND

Smoking is considered a risk factor for bacterial vaginosis. It is currently unknown which parameters of the vaginal environment are affected and how smoking triggers the disease.

AIM OF THE STUDY

The primary objective is to estimate the effect size of smoking on vaginal pH and the Nugent score in patients with chronic vulvovaginal discomfort prior to the development of episode of vaginosis. The secondary goal is to investigate the effect of smoking on individual microscopic parameters of the vaginal environment and on subjectively reported symptoms of vaginal discomfort.

METHODS

Smoking reported by patients was tested as a predictor, using multivariate logistic and ordinal logistic regression analysis on a dataset from the first visit of a randomized trial NCT04171947, which enrolled patients with intermediate vaginal environment. We tested the primary hypothesis (odds ratio (OR) for vaginal pH > 4.5 and Nugent score > 3 in smokers) at the significance level á = 5%. For exploratory analyses of the effect of smoking on the parameters of the vaginal environment, á was corrected as per Bonferoni.

RESULTS

In a cross-sectional sample of 250 women after adjusting for other risk factors, smoking had an impact on the Nugent score (OR = 3.3 (1.3-8.5), P = 0.011), while pH was not affected (OR = 1.2 (0.5-2.8), P = 0.698). Smoking was associated with the prevalence of clue cells (P < 0.000), Gardnerella spp. (P = 0.001) and Mobiluncus spp. (P = 0.001), while the prevalence of Lactobacillus remained unchanged (P = 0.049).

CONCLUSION

Contrarily to common assumptions, vaginal Lactobacillus is not directly affected by smoking, which rather promotes the growth of bacteria of Gardnerella and Mobiluncus spp. Given that other parameters remained unaffected, it appears that smoking leads to vaginal dysbio-sis by creating specific favourable conditions for these two opportunistic  pathogens.

Intrauterine colonization with Gardnerella vaginalis and Mobiluncus mulieris induces maternal inflammation but not preterm birth in a mouse model

PROBLEM

Preterm birth (PTB) remains a leading cause of childhood mortality. Recent studies demonstrate that the risk of spontaneous PTB (sPTB) is increased in individuals with Lactobacillus-deficient vaginal microbial communities. One proposed mechanism is that vaginal microbes ascend through the cervix, colonize the uterus, and activate inflammatory pathways leading to sPTB. This study assessed whether intrauterine colonization with either Gardnerella vaginalis and Mobiluncus mulieris alone is sufficient to induce maternal-fetal inflammation and induce sPTB.

METHOD OF STUDY

C56/B6J mice, on embryonic day 15, received intrauterine inoculation of saline or 108 colony-forming units of G. vaginalis (n = 30), M. mulieris (n = 17), or Lactobacillus crispatus (n = 16). Dams were either monitored for maternal morbidity and sPTB or sacrificed 6 h post-infusion for analysis of bacterial growth and cytokine/chemokine expression in maternal and fetal tissues.

RESULTS

Six hours following intrauterine inoculation with G. vaginalis, M. mulieris, or L. crispatus, live bacteria were observed in both blood and amniotic fluid, and a potent immune response was identified in the uterus and maternal serum. In contrast, only a limited immune response was identified in the amniotic fluid and the fetus after intrauterine inoculation. High bacterial load (108 CFU/animal) of G. vaginalis was associated with maternal morbidity and mortality but not sPTB. Intrauterine infusion with L. crispatus or M. mulieris at 108 CFU/animal did not induce sPTB, alter pup viability, litter size, or maternal mortality.

CONCLUSIONS

Despite inducing an immune response, intrauterine infusion of live G. vaginalis or M. mulieris is not sufficient to induce sPTB in our mouse model. These results suggest that ascension of common vaginal microbes into the uterine cavity alone is not causative for sPTB.

Peptoniphilus genitalis sp. nov. and Mobiluncus massiliensis sp. nov.: Novel Bacteria Isolated from the Vaginal Microbiome

The strains Marseille-Q7072T (= CSUR Q7072T = CECT 30604 T) and Marseille-Q7826T (= CSUR Q7826T = CECT 30727 T) were isolated from vaginal samples. As MALDI-TOF mass spectrometry failed to identify them, their genomes were directly sequenced to determine their taxogenomic identities. Both strains are anaerobic without any oxidase and catalase activity. C16:0 is the most abundant fatty acid for both strains. Strain Marseille-Q7072T is non-spore-forming, non-motile, Gram-stain-positive, and coccus-shaped, while strain Marseille-Q7826T is non-spore-forming, motile, Gram-stain-variable, and curved rod-shaped. The genomic comparison of the Marseille-Q7072T and Marseille-Q7826T strains showed that all digital DNA-DNA hybridisation (dDDH) and mean orthologous nucleotide identity (OrthoANI) values were below published species thresholds (70% and 95-96%, respectively) with other closely related species with standing in nomenclature. Thus, we conclude that both strains are new bacterial species. Strain Marseille-Q7072T is a new member of the Bacillota phylum, for which the name Peptoniphilus genitalis sp. nov. is proposed, while the Marseille-Q7826T strain is a new member of the Actinomycetota phylum, for which the name Mobiluncus massiliensis sp. nov. is proposed.

[Prevalence of bacterial vaginosis in an obstetric population of Barcelona]

OBJECTIVES

To investigate the prevalence and risk factors of bacterial vaginosis (BV) in a pregnant population of Barcelona (Spain).

MATERIAL AND METHODS

301 pregnant women controlled in the Hospital Clinic i Provincial (HCP) of Barcelona were enrolled in the study. Complete epidemiological information, and vaginal samples were available in 293 women. BV was diagnosed by Gram stain of vaginal smear (Nugent's criteria).

RESULTS

BV was detected in 22 pregnant women (7.5%; 95% CI: 4.6-10.5%). There was no association between race, parity, education, marital status, smoking and drug use, and the presence of BV. Non-use of birth control method (72.3% vs 34.4%; p < 0.0001), presence of sexually transmitted diseases (STD) during pregnancy (22.7% vs 3.7%; p < 0.0001), HIV seropositivity (13.6% vs 2.9%; p = 0.041) and presence of symptoms of vaginitis (40.9% vs 13.3%; p = 0.009) were significantly associated with the presence of BV.

CONCLUSIONS

The prevalence of BV in a pregnant population of Barcelona (Spain) is 7.5%. Further work is needed to evaluate the usefulness of BV as a prescreening marker for STD and HIV infection. The Gram stain provides an inexpensive, fast and easy method to diagnose BV, and may allow us to screen, treat and prevent the morbidity and mortality associated with it.

Extracellular vesicles from vaginal Gardnerella vaginalis and Mobiluncus mulieris contain distinct proteomic cargo and induce inflammatory pathways

Colonization of the vaginal space with bacteria such as Gardnerella vaginalis and Mobiluncus mulieris is associated with increased risk for STIs, bacterial vaginosis, and preterm birth, while Lactobacillus crispatus is associated with optimal reproductive health. Although host-microbe interactions are hypothesized to contribute to reproductive health and disease, the bacterial mediators that are critical to this response remain unclear. Bacterial extracellular vesicles (bEVs) are proposed to participate in host-microbe communication by providing protection of bacterial cargo, delivery to intracellular targets, and ultimately induction of immune responses from the host. We evaluated the proteome of bEVs produced in vitro from G. vaginalis, M. mulieris, and L. crispatus, identifying specific proteins of immunologic interest. We found that bEVs from each bacterial species internalize within cervical and vaginal epithelial cells, and that epithelial and immune cells express a multi-cytokine response when exposed to bEVs from G. vaginalis and M. mulieris but not L. crispatus. Further, we demonstrate that the inflammatory response induced by G. vaginalis and M. mulieris bEVs is TLR2-specific. Our results provide evidence that vaginal bacteria communicate with host cells through secreted bEVs, revealing a mechanism by which bacteria lead to adverse reproductive outcomes associated with inflammation. Elucidating host-microbe interactions in the cervicovaginal space will provide further insight into the mechanisms contributing to microbiome-mediated adverse outcomes and may reveal new therapeutic targets.