Understanding Community State Types
While each vaginal microbiome is distinctive, recent studies have categorised them into five general groups, often referred to as Community State Types (CSTs)​1​.
As research in this area progresses, understanding these vaginal microbiome CSTs can provide valuable insights into your vaginal microbiome’s composition, potential symptoms, and the risk of infections such as bacterial vaginosis (BV) or aerobic vaginitis (AV).
The primary distinguishing factor among these vaginal microbiome community state types is the type and quantity of Lactobacillus bacteria, a pivotal component for many in maintaining vaginal microbiome health​2​. Lactobacilli contribute to vaginal health in various ways​3​:
- Regulating pH Levels: They produce lactic acid, a substance that helps maintain an optimal and healthy vaginal pH (ideally between 3.8 and 4.5)​2,3​.
- Occupying Space: Lactobacilli live on cells in the vagina, impeding the growth of harmful pathogens​4​.
- Natural Antibiotics: They produce bacteriocins, which act as natural antibiotics​4​.
- Reducing Inflammation: Lactobacilli help in reducing inflammation in the genital tract​4​.
Here’s a closer look at the five vaginal microbiome community state types:
Type 1 – L. crispatus
Type 1 is considered the healthiest​5​ as it has demonstrated the highest success in preventing infections such as BV, STIs​6​, and UTIs​7​. It also carries the lowest risk of other health complications like infertility​8​, preterm birth​9​, and toxic shock syndrome (TSS)​10​.
Lactobacillus crispatus is the key bacterium in Type 1, known to produce both L- and D-lactic acid, maintaining an acidic environment that prevents pathogen proliferation​11–13​.
Type 1 includes two subtypes: Type 1-A and Type 1-B, differing mainly in the percentage of L. crispatus.
Type 2 – L. gasseri
This type is also considered healthy and is dominated by Lactobacillus gasseri. Like L. crispatus, L. gasseri produces D-lactic acid, although in slightly lower quantities​12,14​.
Despite this, Type 2 exhibits robust protection against pathogens​13​ and a reduced risk of infections like BV​13​, UTIs​15​, and STIs​16​. It is also associated with a lower risk of health conditions such as infertility​17​, pelvic inflammatory disease​18​, neonatal issues​19​, and TSS​20​.
Type 3 – L. iners
Dominated by Lactobacillus iners, Type 3 is characterised by versatility. While lactobacilli dominance is generally desired, L. iners can coexist many types of bacteria, making the microbiome more prone to shifting in and out of a healthy state.
When found alongside disruptive bacteria, it can cause symptoms like itching and abnormal discharge. However, in combination with protective lactobacilli, it appears to act neutrally or protectively. Type 3 offers some protection by occupying cells on the vaginal wall and producing L-lactic acid, which helps limit pathogen growth.
However, it is less effective at maintaining an acidic environment compared to other vaginal lactic acids, necessitating a higher number of L. iners to maintain a healthy pH balance.
Research also suggests that L. iners is less protective against STIs and pregnancy complications than other Lactobacillus species. Type 3 has two subtypes: 3-A and 3-B, with no clear distinction in protective capabilities between them.
Type 4 – non-lactobacilli
Characterised by a low presence of lactobacilli and a high diversity of other bacteria, Type 4 may indicate vaginal dysbiosis and an unstable vaginal environment, potentially leading to recurrent infections.
Studies have indicated that a high microbial diversity may elevate the risk of adverse health outcomes such as pregnancy complications, STIs, and pelvic inflammatory disease.
However, having a Type 4 result is not necessarily a cause for concern, as the vaginal microbiome is dynamic and can be influenced by various factors, including medications, supplements, and lifestyle choices.
Notably, not all Type 4 communities are harmful; some women with Type 4 microbiomes may also host protective bacteria like Bifidobacterium.
Furthermore, Type 4 has been subdivided into three subtypes based on the presence of specific bacteria proportions, each potentially associated with various health implications.
Type 5 – L. jensenii
This is considered a healthy vaginal community state type, characterized by domination by Lactobacillus jensenii. L. jensenii contributes to a protective and stable environment by occupying space on the vaginal wall and producing antimicrobial bacteriocins.
Similar to L. crispatus, L. jensenii produces D-lactic acid. Although relatively rare, it is one of the healthiest dominant strains, offering substantial protection against infections like BV, STIs, and UTIs.
Consequently, Type 5 is linked to a very low risk of related health problems (infertility, pelvic inflammatory disease, toxic shock syndrome, and others).
The significance of understanding vaginal microbiome types lies in their dynamic nature. Unlike static genetic results, vaginal microbiomes constantly change due to factors such as birth control, medications, supplements, sexual partners, and lifestyle choices. These changes can occur throughout life, from the very first period to pregnancy, postpartum, and post menopause.
Knowledge about your vaginal microbiome type empowers you to detect potential imbalances early, enabling proactive measures to promote protective bacteria and prevent disruptive ones from taking hold. To discover your classification and complete microbial composition, get an at-home comprehensive vaginal microbiome test.
References
- 1.Ravel J, Gajer P, Abdo Z, et al. Vaginal microbiome of reproductive-age women. Proc Natl Acad Sci USA. Published online June 3, 2010:4680-4687. doi:10.1073/pnas.1002611107
- 2.Amabebe E, Anumba DOC. The Vaginal Microenvironment: The Physiologic Role of Lactobacilli. Front Med. Published online June 13, 2018. doi:10.3389/fmed.2018.00181
- 3.Boris S, Barbés C. Role played by lactobacilli in controlling the population of vaginal pathogens. Microbes and Infection. Published online April 2000:543-546. doi:10.1016/s1286-4579(00)00313-0
- 4.Manhanzva MT, Abrahams AG, Gamieldien H, et al. Inflammatory and antimicrobial properties differ between vaginal Lactobacillus isolates from South African women with non-optimal versus optimal microbiota. Sci Rep. Published online April 10, 2020. doi:10.1038/s41598-020-62184-8
- 5.Petrova MI, Lievens E, Malik S, Imholz N, Lebeer S. Lactobacillus species as biomarkers and agents that can promote various aspects of vaginal health. Front Physiol. Published online March 25, 2015. doi:10.3389/fphys.2015.00081
- 6.Nardini P, Ñahui Palomino RA, Parolin C, et al. Lactobacillus crispatus inhibits the infectivity of Chlamydia trachomatis elementary bodies, in vitro study. Sci Rep. Published online June 29, 2016. doi:10.1038/srep29024
- 7.Ghartey JP, Smith BC, Chen Z, et al. Lactobacillus crispatus Dominant Vaginal Microbiome Is Associated with Inhibitory Activity of Female Genital Tract Secretions against Escherichia coli. Desvaux M, ed. PLoS ONE. Published online May 7, 2014:e96659. doi:10.1371/journal.pone.0096659
- 8.Vitale SG, Ferrari F, Ciebiera M, et al. The Role of Genital Tract Microbiome in Fertility: A Systematic Review. IJMS. Published online December 24, 2021:180. doi:10.3390/ijms23010180
- 9.Feehily C, Crosby D, Walsh CJ, et al. Shotgun sequencing of the vaginal microbiome reveals both a species and functional potential signature of preterm birth. npj Biofilms Microbiomes. Published online November 12, 2020. doi:10.1038/s41522-020-00162-8
- 10.Jacquemond I, Muggeo A, Lamblin G, et al. Complex ecological interactions of Staphylococcus aureus in tampons during menstruation. Sci Rep. Published online July 2, 2018. doi:10.1038/s41598-018-28116-3
- 11.Almeida MO, Carmo FLR do, Gala-GarcÃa A, et al. Research Article <i>Lactobacillus</i> <i>crispatus</i> protects against bacterial vaginosis. Genet Mol Res. Published online 2019. doi:10.4238/gmr18475
- 12.Witkin SS, Mendes-Soares H, Linhares IM, Jayaram A, Ledger WJ, Forney LJ. Influence of Vaginal Bacteria and <scp>d</scp> – and <scp>l</scp> -Lactic Acid Isomers on Vaginal Extracellular Matrix Metalloproteinase Inducer: Implications for Protection against Upper Genital Tract Infections. Blaser MJ, ed. mBio. Published online August 30, 2013. doi:10.1128/mbio.00460-13
- 13.Atassi F, Pho Viet Ahn DL, Lievin-Le Moal V. Diverse Expression of Antimicrobial Activities Against Bacterial Vaginosis and Urinary Tract Infection Pathogens by Cervicovaginal Microbiota Strains of Lactobacillus gasseri and Lactobacillus crispatus. Front Microbiol. Published online December 20, 2019. doi:10.3389/fmicb.2019.02900
- 14.van de Wijgert JHHM, Borgdorff H, Verhelst R, et al. The Vaginal Microbiota: What Have We Learned after a Decade of Molecular Characterization? Fredricks DN, ed. PLoS ONE. Published online August 22, 2014:e105998. doi:10.1371/journal.pone.0105998
- 15.Hudson PL, Hung KJ, Bergerat A, Mitchell C. Effect of Vaginal Lactobacillus Species on Escherichia coli Growth. Female Pelvic Med Reconstr Surg. Published online February 2020:146-151. doi:10.1097/spv.0000000000000827
- 16.Shipitsyna E, Khusnutdinova T, Budilovskaya O, et al. Bacterial vaginosis-associated vaginal microbiota is an age-independent risk factor for Chlamydia trachomatis, Mycoplasma genitalium and Trichomonas vaginalis infections in low-risk women, St. Petersburg, Russia. Eur J Clin Microbiol Infect Dis. Published online February 8, 2020:1221-1230. doi:10.1007/s10096-020-03831-w
- 17.Okwelogu SI, Ikechebelu JI, Agbakoba NR, Anukam KC. Microbiome Compositions From Infertile Couples Seeking In Vitro Fertilization, Using 16S rRNA Gene Sequencing Methods: Any Correlation to Clinical Outcomes? Front Cell Infect Microbiol. Published online October 1, 2021. doi:10.3389/fcimb.2021.709372
- 18.Edwards VL, Smith SB, McComb EJ, et al. The Cervicovaginal Microbiota-Host Interaction Modulates Chlamydia trachomatis Infection. Clemente JC, ed. mBio. Published online August 27, 2019. doi:10.1128/mbio.01548-19
- 19.Gudnadottir U, Debelius JW, Du J, et al. The vaginal microbiome and the risk of preterm birth: a systematic review and network meta-analysis. Sci Rep. Published online May 13, 2022. doi:10.1038/s41598-022-12007-9
- 20.MacPhee RA, Miller WL, Gloor GB, et al. Influence of the Vaginal Microbiota on Toxic Shock Syndrome Toxin 1 Production by Staphylococcus aureus. Appl Environ Microbiol. Published online March 15, 2013:1835-1842. doi:10.1128/aem.02908-12
