Vaginal Bacteria and Risk of Incident and Persistent Infection With High-Risk Subtypes of Human Papillomavirus: A Cohort Study Among Kenyan Women

Interpretation of vaginal metagenomic characteristics in different types of vaginitis

Although vaginitis is closely related to vaginal microecology in females, the precise composition and functional potential of different types of vaginitis remain unclear. Here, metagenomic sequencing was applied to analyze the vaginal flora in patients with various forms of vaginitis, including cases with a clue cell proportion ranging from 1% to 20% (Clue1_20), bacterial vaginitis (BV), vulvovaginal candidiasis (VVC), and BV combined with VVC (VVC_BV). Our results identified Prevotella as an important biomarker between BV and Clue1_20. Moreover, a gradual decrease was observed in the relative abundance of shikimic acid metabolism associated with bacteria producing indole as well as a decline in the abundance of Gardnerella vaginalis in patients with BV, Clue1_20, and healthy women. Interestingly, the vaginal flora of patients in the VVC_BV group exhibited structural similarities to that of the VVC group, and its potentially functional characteristics resembled those of the BV and VVC groups. Finally, Lactobacillus crispatus was found in high abundance in healthy samples, greatly contributing to the stability of the vaginal environment. For the further study of L. crispatus, we isolated five strains of L. crispatus from healthy samples and evaluated their capacity to inhibit G. vaginalis biofilms and produce lactic acid in vitro to select the potential probiotic candidate for improving vaginitis in future clinical studies. Overall, we successfully identified bacterial biomarkers of different vaginitis and characterized the dynamic shifts in vaginal flora between patients with BV and healthy females. This research advances our understanding and holds great promise in enhancing clinical approaches for the treatment of vaginitis.

IMPORTANCE

Vaginitis is one of the most common gynecological diseases, mostly caused by infections of pathogens such as Candida albicans and Gardnerella vaginalis. In recent years, it has been found that the stability of the vaginal flora plays an important role in vaginitis. Furthermore, the abundant Lactobacillus-producing rich lactic acid in the vagina provides a healthy acidic environment such as Lactobacillus crispatus. The metabolites of Lactobacillus can inhibit the colonization of pathogens. Here, we collected the vaginal samples of patients with bacterial vaginitis (BV), vulvovaginal candidiasis (VVC), and BV combined with VVC to discover the differences and relationships among the different kinds of vaginitis by metagenomic sequencing. Furthermore, because of the importance of L. crispatus in promoting vaginal health, we isolated multiple strains from vaginal samples of healthy females and chose the most promising strain with potential probiotic benefits to provide clinical implications for treatment strategies.

Cervicovaginal microbiota long-term dynamics and prediction of different outcomes in persistent human papillomavirus infection

Persistent human papillomavirus (HPV) infection can lead to cervical intraepithelial neoplasia (CIN) and cervical cancer, posing serious threats to the health of women. Although the cervicovaginal microbiota is strongly associated with CIN, the dynamics of the microbiota during CIN development are unknown. In this retrospective cohort study, we analyzed 3-year longitudinal data from 72 patients diagnosed with a persistent HPV infection almost all caused by high-risk HPV types. Patients were categorized into groups with HPV persistent infection (n = 37), progression to CIN (n = 16), and CIN regression (n = 19) based on infection outcome during the follow-up period. Furthermore, 16S rRNA gene sequencing was performed on consecutively collected cervical samples to explore the composition and dynamics of the cervicovaginal microbiota during the development and regression of CIN. Our results showed that the composition of the cervicovaginal microbiota varied among women with different HPV infection outcomes and remained relatively stable during the follow-up period. Notably, the serial follow-up data showed that these microbial alterations were present for at least 1-2 years and occurred before pathologic changes. In addition, microbial markers that were highly discriminatory for CIN progression or regression were identified. This study provides evidence for a temporal relationship between changes in the cervicovaginal microbiota and the development of CIN, and our findings provide support for future microbial intervention strategies for CIN.

Effect of Probiotics on Host-Microbiota in Bacterial Infections

Diseases caused by bacteria cause millions of deaths every year. In addition, the problem of resistance to antibiotics is so serious that it threatens the achievements of modern medicine. This is a very important global problem as some bacteria can also develop persistence. Indeed, the persistence of pathogenic bacteria has evolved as a potent survival strategy to overcome host organisms’ defense mechanisms. Additionally, chronic or persistent infections may be caused by persisters which could facilitate antibiotic resistance. Probiotics are considered good bacteria. It has been described that the modulation of gut microbiota by probiotics could have a great potential to counteract the deleterious impact and/or regulate gut microbiota after bacterial infection. Probiotics might provide health benefits through the inhibition of pathogen growth or the replacement of pathogenic bacteria. Bearing in mind that current strategies to avoid bacterial persistence and prevent antibiotic resistance are not effective, other strategies need to be assessed. We have carried out a comprehensive review, which included the reported literature between 2016 and 2021, highlighting the clinical trials that reported the probiotics’ potential to regulate gut microbiota after bacterial infection and focusing in particular on the context of antibiotic resistance and persister cells.

Vaginal microbiota associated with oncogenic HPV in a cohort of HPV-vaccinated women living with HIV

Background

Women living with HIV (WLWH) experience higher rates of human papillomavirus (HPV) infection and cervical cancer than women without HIV. Changes in the vaginal microbiome have been implicated in HPV-related disease processes such as persistence of high-risk HPV infection but this has not been well defined in a population living with HIV.

Methods

Four hundred and 20 girls and WLWH, age ≥9, across 14 clinical sites in Canada were enrolled to receive three doses of quadrivalent HPV vaccine for assessment of vaccine immunogenicity. Blood, cervical cytology, and cervico-vaginal swabs were collected. Cervico-vaginal samples were tested for HPV DNA and underwent microbiota sequencing.

Results

Principal component analysis (PCA) and hierarchical clustering generated community state types (CSTs). Relationships between taxa and CSTs with HPV infection were examined using mixed-effects logistic regressions, Poisson regressions, or generalized linear mixed-effects models, as appropriate. Three hundred and fifty-six cervico-vaginal microbiota samples from 172 women were sequenced. Human papillomavirus DNA was detected in 211 (59%) samples; 110 (31%) contained oncogenic HPV. Sixty-five samples (18%) were taken concurrently with incident oncogenic HPV infection and 56 (16%) were collected from women with concurrent persistent oncogenic HPV infection.

Conclusions

No significant associations between taxa, CST, or microbial diversity and HPV-related outcomes were found. However, we observed weak associations between a dysbiotic microbiome and specific species, including Gardnerella, Porphyromonas, and Prevotella species, with incident HPV infection.