Lactobacillus iners-dominated vaginal microbiota is associated with increased susceptibility to Chlamydia trachomatis infection in Dutch women: a case-control study

Abstract

Introduction: This prospective study aimed to study the composition and structure of the vaginal microbiota prior to Chlamydia trachomatis infection.

Methods: A nested case-control study was performed in 122 women, half of which acquired C. trachomatis within a year after their first visit. At the first visit, the composition and structure of vaginal microbial communities were analysed using 16S rRNA sequencing in the context of the sociodemographic and sexual risk behaviour information using logistic regression.

Results: Five vaginal community state types (CSTs) were identified. Four CSTs were dominated by Lactobacillus spp., of which L. crispatus (37%) and L. iners (33%) were the most common. One CST was characterised by the absence of Lactobacillus spp. (25%) and the presence of an array of strict and facultative anaerobes. Multivariate logistic regression analysis revealed that women with a L. iners-dominated CST had an increased risk of C. trachomatis infection (p=0.04; OR: 2.6, 95% CI 1.0 to 6.6).

Conclusions: The distribution of CSTs dominated by Lactobacillus spp. agreed with previous studies. However, the frequency of dysbiosis among Caucasian women was relatively high (24%). Having vaginal microbiota dominated by L. iners was associated with an increased risk for C. trachomatis infection. Therefore, we hypothesise that specific signatures of vaginal microbiota are indicative of increased host predisposition to acquiring STIs.

Keywords: chlamydia infection; molecular epidemiology; sexual health; vaginal microbiology; women.

Figure 1.

Hierarchical clustering of 115 vaginal samples from 60 women acquiring a C. trachomatis infection and 55 women who do not, within a year after entering the study. The dendrogram was generated using complete linkage clustering with Euclidean distance, based on the relative abundance of taxa in each sample. Relative abundance is illustrated by the colour key. The higher the abundance of a certain microbial species in a sample is, the more red it becomes. Sidebars depict the various community state types that could be assigned to the various clusters (CST I-V), acquiring C. trachomatis (in red), ethnicity, and the number of sexual partners in the past six months.

Figure 2.

Association between microbial taxa and the acquisition of C. trachomatis. LEfSe analysis identified significantly abundant microbial taxa, when comparing samples collected from women who acquire C. trachomatis and women who do not with an alpha value <0.05. The taxa are ranked according to their effect size that are associated with different conditions with the highest median. The Linear Discriminant Analysis (LDA) score at the log10 scale is indicated at the bottom. The greater the LDA score is, the more significant the specific microbial taxa are in the comparison.