Probiotics ensure “healthy vaginas” or so they say

by Zahraa Ahmed

The term “healthy vaginas” has a certain cringe factor for obvious reasons: it suggests that some women might have “unhealthy vaginas”! This is an example of medical colloquialism at its most harmful. “Healthy vaginas” actually refer to the bacteria present in the female genital tract (FGT), where some species are beneficial as they keep the pH of the FGT within the acidic range which is harmful to invading bacteria and viruses. These types of bacteria are called Lactobacillus and they are not only harmless but also protective against infections. However, sometimes there can be an imbalance where Lactobacillus stops growing, and other bacteria begin to overgrow. The displacement of Lactobacillus with other harmful bacteria results in a vaginal infection called bacterial vaginosis. Research has shown that the symptoms associated with BV, which include abnormal vaginal discharge and odour, negatively impacts women’s self-esteem and sex lives as these symptoms made women feel “embarrassed” and “dirty” (Bilardi et al., 2013). It is important to note that BV is not a sexually transmitted infection (STI). However, BV place’s women at a higher risk of contracting STI’s such as HIV, as well as infertility, pelvic inflammatory disease and adverse pregnancy outcomes such as preterm birth.

Interestingly, BV was originally called Gardnerella vaginitis as it was believed that the bacterium, Gardnerella vaginalis (G. vaginalis), was the cause of the vaginal infection (Kairys et al., 2002). However, G. vaginalis was later identified to be the initial bacteria that adhere to vaginal epithelial cells, and is assisted by other harmful bacteria to promote the development of BV. G. vaginalis is believed to be the major contributor to BV due to its ability to form biofilms and produce proteins such as sialidase and vaginolysin. Sialidase breaks down sugars in the FGT and by doing so provides an important source of nourishment to G. vaginalis and other BV-associated bacteria. Vaginolysin forms holes within the lining of the FGT which results in inflammation due to the further tissue destruction created by the body’s immune response. Currently, the standard treatment for BV is associated with antibiotic resistance. It has been suggested that the ability of G. vaginalis to form biofilms, which are thick layers of bacteria and cell debris which allows bacteria to grow undercover, are responsible for the treatment failure and reoccurrence of BV.

In this article Qian et al. investigated whether the introduction of a high number of Lactobacillus could outgrow G. vaginalis,and restore the FGT to its healthy state. To accomplish this, the authors looked at the applicability of three Lactobacillus strains (Lactobacillus delbrueckii DM8909, Lactiplantibacillus plantarum ATCC14917 and Lactiplantibacillus plantarum ZX27) to outcompete G. vaginalis. Several experiments were performed to determine whether the Lactobacillus species prevented the growth, adhesion, biofilm formation and inhibited sialidase and vaginolysin activity of G. vaginalis.

The authors concluded that all three Lactobacillus species were able to inhibit growth, reduce adherence, inhibit biofilm formation, as well as decrease sialidase and vaginolysin levels. Based on the effect of the Lactobacillus species on G. vaginalis adhesion and biofilm formation it can be concluded that the use of probiotics as a daily supplement can benefit women as an adjuvant treatment or preventative. The results identified Lactiplantibacillus plantarum ZX27 as the most protective strain against G. vaginalis as it was able to decrease the pH to a much greater extent due to its high lactic acid production. It is thus possible that vaginas could be restored to their healthy state by the mere introduction of Lactiplantibacillus plantarum ZX27 into the FGT, hopefully reducing the shame associated with BV and leaving women with sweet smelling vaginas.


Bilardi, J.E., Walker, S., Temple-Smith, M., McNair, R., Mooney-Somers, J., Bellhouse, C., Fairley, C.K., Chen, M.Y. and Bradshaw, C., 2013. The burden of bacterial vaginosis: women’s experience of the physical, emotional, sexual and social impact of living with recurrent bacterial vaginosis. PloS one, 8(9), p.e74378.

Kairys, N. and Garg, M., 2017. Bacterial vaginosis. StatPearls.

Qian, Z., Zhu, H., Zhao, D., Yang, P., Gao, F., Lu, C., Yin, Y., Kan, S. and Chen, D., 2021. Probiotic Lactobacillus sp. Strains Inhibit Growth, Adhesion, Biofilm Formation, and Gene Expression of Bacterial Vaginosis-Inducing Gardnerella vaginalis. Microorganisms, 9(4), p.728.

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