Vaginal flora, an indicator for the risk of developing an STI

Actu GP infections Chlamydia

Around a quarter of Caucasian women have vaginal dysbiosis that increases the risk of Chlamydia infection, according to a Dutch study.


Chlamydia trachomatis infections are the most common sexually transmitted infections (STI). Generally symptomless, they can still compromise fertility for a couple.

The vaginal microbiota is thought to play a role in protecting against STIs, and more particularly the lactobacilli whose production of lactic acid creates an unfavorable environment for its colonization by pathogens. From there, Dutch researchers took the step of deducing that alterations in the composition of the microbiota may make infection more likely by disrupting the vaginal equilibrium, which they tested in a study of 122 women.

They compared the vaginal microbiota from all the volunteers before half of them developed Chlamydia infection. They observed notable differences with two groups of Lactobacilli, Lactobacillus iners and Lactobacillus crispatus. By extending their analysis, they established a very strong link between a predominance of L. iners and an increased risk of infection, and, conversely, between an abundance of L. crispatus and not developing infection. These results confirm their hypothesis, and led the researchers to conclude that some women may be predisposed to developing Chlamydia infection.


van Houdt R et al. Lactobacillus iners-dominated vaginal microbiota is associated with increased susceptibility to Chlamydia trachomatis infection in Dutch women: a case-control study. Sex Transm Infect. 2017 Sep 25. pii: sextrans-2017-053133