Genital chlamydia remains the most common bacterial sexually transmitted infection worldwide, with a particularly high incidence among adolescents and young adults, with an overall increase of 13% in the number of infections between 2013 and 2023.

In order to better understand this problem and its impact, a group of researchers from the RISE-Health Research Unit and the Faculty of Medicine of the University of Porto analysed the role of the cervicovaginal microbiota in female reproductive tract health.

The cervicovaginal microbiota ‘is a dynamic ecosystem of microorganisms that lines the vagina and cervix and acts as a true “front line” of defence for the female reproductive tract,’ explains Nuno Vale, principal investigator of the Personalised Medicine Group at RISE-Health@ RISE/FMUP, adding that ‘in addition to the physical-chemical barrier, this microbiota modulates the local immune response, influences mucosal inflammation and can impact processes such as the ascent of microorganisms to the uterus and fallopian tubes, fertility, embryo implantation and pregnancy outcomes’.

“When this microbiota is “disorganised” (dysbiosis), for example, with a loss of Lactobacillus and an increase in anaerobes such as Gardnerella, Prevotella or Atopobium, the risk of sexually transmitted infections, including Chlamydia trachomatis, and upstream complications such as pelvic inflammatory disease, tubal infertility, and ectopic pregnancy increases,” explains the Associate Professor at the Faculty of Medicine of the University of Porto (FMUP).

According to the study published in the International Journal of Molecular Sciences, ‘the composition of the cervicovaginal microbiota varies throughout a woman’s life, influenced by various physiological, hormonal and environmental factors,’ pointing out that a cervicovaginal flora dominated by Lactobacillus, also known as ‘good cells,’ particularly enriched in L. crispatus, ‘supports the integrity of the epithelial barrier, limits inflammation and promotes the spontaneous elimination of pathogens’.

In the experts’ view, ‘microbiota-focused interventions are promising because they can boost natural immunity, improve vaccine efficacy, reduce morbidity associated with genital chlamydia, and even reduce the incidence of other sexually transmitted infections.’

‘Implementing more structured screening strategies, particularly in sexually active adolescents and young adults’, ‘facilitating access to diagnosis at the first level of care’, ‘ensuring adequate and timely treatment, in accordance with European and national standards and guidelines’, ‘strengthening the notification and treatment of sexual partners’ and the development of ‘sex education and health literacy programmes that integrate information on STIs, the importance of screening, condom use and the impact of chlamydia on female and male fertility’ should be among the measures adopted to combat the increase in genital chlamydia infection.

In addition to researcher Nuno Vale, the article “Disrupted Cervicovaginal Microbiota: Its Role in Chlamydia trachomatis Genital Infection and Associated Reproductive Outcomes” was co-authored by Rafaela Rodrigues, a PhD student in the Clinical Research and Health Services Doctoral Programme (PDICSS) at FMUP, Ana Rita Silva and Carlos Sousa (RISE-Health@RISE/FMUP).