Characteristics of the vaginal microbiomes in prepubertal girls with and without vulvovaginitis

Premature rupture of membranes and changes in the vaginal microbiome - Probiotics

Preterm birth affects approximately 15 million women worldwide, of which 30 % is due to preterm premature rupture of membranes (PPROM). The reasons for shortening the duration of pregnancy are seen in genetic, hormonal, immunological and socio-economic conditions. Recent years have provided a lot of evidence on the impact of the microbiota and whole microbiome on pregnant women, suggesting that the microorganisms inhabiting the vagina significantly affect the risk of preterm delivery. The aim of the study was to review studies evaluating the composition of the vaginal microflora and its role in the occurrence of preterm labor caused by PPROM, and to evaluate the potential beneficial effect of probiotics on preventing the development of preterm labor. Vaginal microbial dysbiosis is observed in PPROM, which, due to its association with a high risk of prematurity and infection, increases neonatal morbidity and mortality. Further research on biomarkers for screening, early prognosis and diagnosis of PPROM seems advisable. Probiotics as a potential intervention can prevent the development of pathological vaginal flora, reducing the risk of infection in women planning pregnancy and pregnant women.

Bacterial dysbiosis and epithelial status of the California sea lion (Zalophus californianus) in the Gulf of California

Despite the high incidence of urogenital carcinoma (UGC) in California sea lions stranded along California, no UGC has been reported in other areas of their distribution; however, cell morphologies typical of premalignant states have been found. Risk factors for UGC include high of organochlorines and infection with a gammaherpesvirus, OtHV-1, but the importance of the bacteriome for epithelial status remains unknown. We characterized the genital bacteriome of adult female California sea lions along their distribution in the Gulf of California and examined whether the diversity and abundance of the bacteriome varied spatially, whether there were detectable differences in the bacteriome between healthy and altered epithelia, and whether the bacteriome was different in California sea lions infected with OtHV-1 or papillomavirus. We detected 2270 ASVs in the genital samples, of which 35 met the criteria for inclusion in the core bacteriome. Fusobacteriia and Clostridia were present in all samples, at high abundances, and Actinobacteria, Alphaproteobacteria, and Campylobacteria were also well-represented. Alpha diversity and abundance of the California sea lion genital bacteriome varied geographically. The abundance of bacterial ASVs varied depending on the genital epithelial status and inflammation, with differences driven by classes Fusobacteriia, Clostridia, Campylobacteria and Alphaproteobacteria. Alpha diversity and abundance were lowest in samples in which OtHV-1 was detected, and highest those with papillomavirus. Our study is the first investigation of how the bacteriome is related to epithelial status in a wild marine species prone to developing cancer.

Sexual behavior shapes male genitourinary microbiome composition

The origin, composition, and significance of the distal male urethral microbiome are unclear, but vaginal microbiome dysbiosis is linked to new sex partners and several urogynecological syndromes. We characterized 110 urethral specimens from men without urethral symptoms, infections, or inflammation using shotgun metagenomics. Most urethral specimens contain characteristic lactic acid bacteria and Corynebacterium spp. In contrast, several bacteria associated with vaginal dysbiosis were present only in specimens from men who reported vaginal intercourse. Sexual behavior, but not other evaluated behavioral, demographic, or clinical variables, strongly associated with inter-specimen variance in urethral microbiome composition. Thus, the male urethra supports a simple core microbiome that is established independent of sexual exposures but can be re-shaped by vaginal sex. Overall, the results suggest that urogenital microbiology and sexual behavior are inexorably intertwined, and show that the male urethra harbors female urogenital pathobionts.

Female reproductive tract-organ axes

The female reproductive tract (FRT) and remote/versatile organs in the body share bidirectional communication. In this review, we discuss the framework of the "FRT-organ axes." Each axis, namely, the vagina-gut axis, uterus-gut axis, ovary-gut axis, vagina-bladder axis, vagina-oral axis, uterus-oral axis, vagina-brain axis, uterus-brain axis, and vagina-joint axis, is comprehensively discussed separately. Each axis could be involved in the pathogenesis of not only gynecological diseases but also diseases occurring apart from the FRT. Although the microbiota is clearly a key player in the FRT-organ axes, more quantitative insight into the homeostasis of the microbiota could be provided by host function measurements rather than current microbe-centric approaches. Therefore, investigation of the FRT-organ axes would provide us with a multicentric approach, including immune, neural, endocrine, and metabolic aspects, for understanding the homeostatic mechanism of women's bodies. The framework of the FRT-organ axes could also provide insights into finding new therapeutic approaches to maintain women's health.

Host and Microbiome Interplay Shapes the Vaginal Microenvironment

The female reproductive tract harbors a unique microbiome, especially the vagina. The human vaginal microbiome exhibits a low diversity and is dominated by Lactobacillus species, compared to the microbiome of other organs. The host and vaginal microbiome mutually coexist in the vaginal microenvironment. Host cells provide Lactobacillus glycogen as an energy source, and Lactobacillus produce lactic acid, which lowers vaginal pH thereby preventing growth of other bacteria. Bacterial vaginosis can modulate host immune systems, and is frequently associated with various aspects of disease, including sexually transmitted infection, gynecologic cancer, and poor pregnancy outcomes. Because of this, numerous studies focused on the impact of the vaginal microbiome on women`s health and disease. Furthermore, numerous epidemiologic studies also have demonstrated various host factors regulate the vaginal microbiome. The female reproductive tract undergoes constant fluctuations due to hormonal cycle, pregnancy, and other extrinsic factors. Depending on these fluctuations, the vaginal microbiome composition can shift temporally and dynamically. In this review, we highlight the current knowledge of how host factors modulate vaginal microbiome composition and how the vaginal microbiome contributes to maintaining homeostasis or inducing pathogenesis. A better understanding of relationship between host and vaginal microbiome could identify novel targets for diagnosis, prognosis, or treatment of microbiome-related diseases.

Towards a deeper understanding of the vaginal microbiota

The human vaginal microbiota is a critical determinant of vaginal health. These communities live in close association with the vaginal epithelium and rely on host tissues for resources. Although often dominated by lactobacilli, the vaginal microbiota is also frequently composed of a collection of facultative and obligate anaerobes. The prevalence of these communities with a paucity of Lactobacillus species varies among women, and epidemiological studies have associated them with an increased risk of adverse health outcomes. The mechanisms that drive these associations have yet to be described in detail, with few studies establishing causative relationships. Here, we review our current understanding of the vaginal microbiota and its connection with host health. We centre our discussion around the biology of the vaginal microbiota when Lactobacillus species are dominant versus when they are not, including host factors that are implicated in shaping these microbial communities and the resulting adverse health outcomes. We discuss current approaches to modulate the vaginal microbiota, including probiotics and vaginal microbiome transplants, and argue that new model systems of the cervicovaginal environment that incorporate the vaginal microbiota are needed to progress from association to mechanism and this will prove invaluable for future research.

Microbiological findings in prepubertal and pubertal girls with vulvovaginitis

Vulvovaginitis is a common and challenging gynaecological problem in prepubertal and pubertal girls. Such an infection, owing to a wide range of aetiologies, if not responding to hygienic measures, needs further investigation through vaginal cultures, since treatment should be tailored accordingly. This study aimed to investigate the pathogens isolated in prepubertal and pubertal girls with signs and symptoms of vulvovaginitis. A total of 2314 symptomatic girls, 1094 prepubertal and 1220 pubertal, aged 2 to 16 years, were included. Vaginal samples were inoculated on specific culture plates followed by incubation in aerobic, anaerobic or CO₂ atmosphere at 37 °C for 24 or 48 h, as appropriate. The identification of the isolated pathogens was carried out using Gram stain, conventional methods and the automated system VITEK 2 (BioMerieux, Marcy l'Etoile, France). Positive cultures were obtained from 587 (53.7%) of prepubertal girls and 926 (75.9%) of pubertal girls. A total of 613 and 984 pathogens were detected in prepubertal and pubertal subjects, respectively. Isolated bacteria included 40.1% and 22.8% Gram-positive cocci, 35.6% and 24.8% Gram-negative rods in the prepubertal and pubertal groups, respectively, with faecal pathogens being the most prevalent. Bacterial vaginosis was diagnosed in 22.8% of prepubertal and 37.9% of pubertal girls. Candida species were isolated mostly in the pubertal girls (14.5%).

CONCLUSION

Culture results should be evaluated with caution in children with vulvovaginitis. In the prepubertal girls, the most common isolated pathogens were opportunistic bacteria of faecal origin while girls in late puberty were more susceptible to bacterial vaginosis and vulvovaginal candidiasis.

WHAT IS KNOWN

• Vulvovaginitis is the most frequent and challenging reason for referral to paediatric and adolescent gynaecology services. • Microbiological examination can prove to be a significant tool to help diagnosis although results should be evaluated with caution in children.

WHAT IS NEW

• Significantly more positive vaginal cultures and pathogens were recorded in symptomatic pubertal girls compared to prepubertal children. • The prevalence of bacterial vaginosis was increased in both prepubertal and pubertal girls with vulvovaginitis although significantly more in girls at puberty.