Women with vaginal microbiota predominantly populated with Lactobacillus iners are more likely to acquire a Chlamydia trachomatis infection and other sexually transmitted infections, according to a study published in Sexually Transmitted Infections.
“Microbial communities in the vagina are thought to play a protective role against colonization by pathogens responsible for bacterial vaginosis urinary tract infections and STIs among others,” Robin van Houdt, PhD, from the department of medical microbiology and infection control at VU Medical Center in Amsterdam, and colleagues wrote. “Alterations in the composition and structure of vaginal bacterial communities may disturb the homeostasis of the vaginal environment, diminishing the defensive capacities thus increasing host susceptibility to vaginal infections.”
To examine the structure of vaginal microbiota before C. trachomatis, the researchers conducted a nested case-control study which included all sexually active men and women between the ages of 16 and 29 years old who participated in yearly chlamydia screenings. Within a year of the first tests, half of the 112 women included in the study had been infected with C. trachomatis.
On the first visit, van Houdt and colleagues assessed the structure and composition of vaginal microbial communities with 16S rRNA sequencing. The researchers also analyzed sociodemographic and sexual risk factors with logistic regression.
Within the 112 participants, the researchers observed five vaginal community state types. Four of these community state types were composed of Lactobacillus spp., predominantly L. crispatus (37%) and L. iners (33%). The remaining community state type demonstrated a lack of Lactobacillus spp. (25%). The researchers observed the presence of a variety of strict and facultative anaerobes.
Women who had a community state type containing L. iners were more likely to have a later C. trachomatis infection, according to data revealed through multivariate logistic regression (P = .04; OR: 2.6, 95% CI, 1.0-6.6).
“Vaginal microbiota dominated by L. iners at baseline was associated with an increased risk for C. trachomatis infection when assessed a year later. This result might be explained by the fact that vaginal microbiota dominated by L. iners has been shown to exhibit rapid change in composition in and out of community states similar to [bacterial vaginosis],” van Houdt and colleagues wrote. “This might be explained by the larger diversity observed in the L. iners-dominated community state types as compared with the L. crispatus-dominated community state types.”
“These findings might indicate that increased risk for STIs is actually not limited to women with [bacterial vaginosis] at time of evaluation, but also women with vaginal microbiota comprising L. iners,” they continued. – by Katherine Bortz
Disclosure: The authors report no financial disclosures.