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What Do We Know About the Vaginal Microbiome?

Abstract


When it comes to the personal care industry for intimate female care products, there is still a lot to be explored and infinitely more that we do not know. For this reason, it is crucial to shed light on current and past research so that we can learn from it and make efforts to widen the literature to bring more effective formulations to the industry. 


The Intimate Care Industry


The intimate care industry for female products is projected to reach USD $69,853 million by 2030 (Acumen Research and Consulting, 2022). For years there has been a stigma linked to women’s intimate care and a lack of willingness to discuss such topics. However, we are seeing a shift towards one that favours openness and education. 

Women’s intimate care products account for approximately 17% of the personal care market, with popularity rising for hygiene products the likes of intimate washes (FMI, 2019). As companies begin to formulate their own products for the needs of this niche of the market, the interesting question arises of what one should look for within these formulations. 


As we have seen in recent years, the skincare industry is seeing a drastic turn towards science-backed products with an increase in demand for microbiome-friendly formulas. However, what do we truly know about the vaginal and vulvar microbiome?


Vaginal Microbiome


The microbiome refers to the microbial population that occupies a habitat with distinct properties. It doesn’t just refer to the microorganisms that live together, but how they interact with one another (Berg et al., 2020). The vaginal microbiome consists of about 9% of the total human microbiome. 


Ordinarily, we find that the microbiome is at its healthiest when the population of bacteria is diverse. This is the case for the skin as well as the gut microbiome. However, research informs that the vaginal and vulvar microbiome act in the opposite way. When there is a high diversity in the vulvar and vaginal microbiome, it draws attention to an underlying problem that needs addressing (Saraf et al., 2021).





In females of reproductive age, it is noted that the Lactobacillus species is a key characteristic of a healthy vaginal microbiome. These include: L. iners, L. crispatus, L. gasseri, and L. jensenii (Saraf et al., 2021). We also find that the same can be said about Bifidobacterium, which suggests protective characteristics as well (Freitas and Hill, 2017). If we look on the opposite side of the spectrum, we note that species such as Prevotella, Atopobium, Gardnerella, Megasphaera, and Mobiluncus are associated with an unhealthy or abnormal vaginal microbiota (Ravel et al., 2011).


Diving Deeper into Vaginal Lactobacillus species


Lactobacillus is characterized as a Gram-positive bacteria with a rod shape. These bacteria are known to produce lactic acid and make the vagina's pH more acidic (<4). According to current research, an acidic environment can restrict the growth of non-indigenous bacteria, which can foster a healthier environment. As a general rule, the lactobacillus species converts sugar into pyruvate which in turn converts it to lactic acid. They can make two types of lactic acid known as D-Lactic acid and L-Lactic acid (Saraf et al., 2021).


Characterizing the Vaginal Microbiome 


In 2011 the concept of Community State Types (CSTs) was introduced with the aim of categorizing the vaginal microbiome communities (Ravel et al., 2011). This categorization was introduced after sampling women of asymptomatic ages through to reproductive women with 16S rRNA Sequencing. As a result, 5 CSTs were found, namely: 


I (L. crispatus): Type 1 is understood to be the healthiest, with research showing that this type can even prevent infections such as STIs, BV, and UTIs.


II (L. gasseri): Type 2 is also linked to a healthy vaginal microbiome, with Lactobacillus gasseri dominating the population of bacteria. 


III (L. iners): Type 3 is neutral meaning it could be disruptive or protective to the vaginal community and is dominated by a species of Lactobacillus known as Lactobacillus iners. 


IV (Diversity group): Type 4 is understood to be an unhealthy vaginal environment with a high diversity of bacteria and low population of lactobacilli. 


V (L. jensenii): Type 5 is another state type acknowledged as healthy with a dominance of Lactobacillus jensenii.


It is interesting to note that within this research females of different ethnic backgrounds fell under different community types. It is crucial to acknowledge that ethnicity plays a key role in the vaginal microbiome and further research is necessitated to understand how it varies from female to female (Ravel et al., 2011).



This image has been pulled out from “Vaginal microbiome of reproductive-age women” (Ravel et al., 2011)


In a paper published in 2020, it is disputed that CSTs needs to go a step further to help classify the vaginal microbiome. That’s where Valencia comes in (or VAginaL community state typE Nearest CentroId clAssifier). It is a centroid-based tool for measuring vaginal microbial communities based on composition (France et al, 2020).  The aim is to classify samples based purely on similarities against a reference that has been defined from 13,160 taxonomic profiles from 1,975 women within the United States. This large dataset allows for a more comprehensive process of identifying, characterizing and defining CSTs. 


Vaginal Microbiota Through the Female Lifespan



Just as with any element of the human body, the vaginal microbiome alters throughout a female’s lifespan, particularly during the menstruating period and after menopause. This is due to the structural and hormonal features of the vaginal tissue (epithelium), which results in a changing environment. It is still not entirely clear what specific changes we can expect to see in each of these stages, as there are many factors at play, including lifestyle, environment and yes, even ethnicity.


In order to uncover more about the vaginal and vulvar microbiome, it is crucial to conduct further studies and test products made for feminine intimate care with the correct methodologies and quantitative analysis to understand their true effect on the microbiome. 


Sequential is a testing company with years of expertise in the field of skin microbiome and genetics. We utilise deep molecular analysis and next-generation sequencing (NGS) technology to understand the impact on an individual’s microbiome from products they use, and the effect from their environment. 


All of our testing is carried out in-vivo and with the utmost care for unearthing the secrets that lie on the surface of the skin.  If you are interested in carrying out any research with us and testing products, you can reach us at team@sequential.bio.


Lexicon 


Community State Types (CSTs): introduced with the aim of categorizing the vaginal microbiome communities (Ravel et al., 2011).


Microbiome: The microbiome is a characteristic microbial community occupying a reasonably well-defined habitat which has distinct physio-chemical properties. The microbiome not only refers to the microorganisms involved but also encompasses their theater of activity, which results in the formation of specific ecological niches. This includes their genetic material, and also structural molecules, like enzymes, membrane lipids or polysaccharides. (Definition based on Berg et al., 2020) 


Skin microbiome: is present on the whole skin surface, including oral cavity and mucosal surfaces of the external genital organs. The composition of the skin microbiome is dynamic, site-specific but also differs from individual to individual. (Definition based on Byrd et al., 2018


Valencia: is a centroid-based tool for measuring vaginal microbial communities based on composition (France et al, 2020).


References


Acumen Research and Consulting. (2021). Feminine hygiene products market size worth around $38.5 billion by 2028. Acumen Research and Consulting. https://www.acumenresearchandconsulting.com/feminine-hygiene-products-market#:~:text=The%20Global%20Feminine%20Hygiene%20Products,have%20grown%20over%20the%20years.


France MT, Ma B, Gajer P, Brown S, Humphrys MS, Holm JB, Waetjen LE, Brotman RM, Ravel J. VALENCIA: a nearest centroid classification method for vaginal microbial communities based on composition. Microbiome. 2020 Nov 23;8(1):166. doi: 10.1186/s40168-020-00934-6. PMID: 33228810; PMCID: PMC7684964.


Freitas, A. C., and Hill, J. E. (2017). Quantification, isolation and characterization of Bifidobacterium from the vaginal microbiomes of reproductive aged women. Anaerobe 47, 145–156. doi: 10.1016/j.anaerobe.2017.05.012 


Ravel, J., Gajer, P., Abdo, Z., Schneider, G. M., Koenig, S. S. K., McCulle, S. L., … Forney, L. J. (2010). Vaginal microbiome of reproductive-age women. Proceedings of the National Academy of Sciences, 108(Supplement_1), 4680–4687. doi:10.1073/pnas.1002611107

Future Market Insights. (2019). Women intimate care market: Global industry analysis 2013-2017 and opportunity assessment 2018-2028. Future Market Insights. https://www.futuremarketinsights.com/reports/women-intimate-care-market


De Seta, F., Campisciano, G., Zanotta, N., Ricci, G., & Comar, M. (2019). The Vaginal Community State Types Microbiome-Immune Network as Key Factor for Bacterial Vaginosis and Aerobic Vaginitis. Frontiers in Microbiology, 10. doi:10.3389/fmicb.2019.02451 


Saraf, V. S., Sheikh, S. A., Ahmad, A., Gillevet, P. M., Bokhari, H., & Javed, S. (2021). Vaginal microbiome: normalcy vs dysbiosis. Archives of Microbiology, 203(7), 3793–3802. doi:10.1007/s00203-021-02414-3 

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