Bacterial vaginosis associated with higher rates of chlamydia persistence
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Key takeaways:
- Bacterial vaginosis is associated with higher rates of chlamydia persistence.
- Optimizing the vaginal microbiome could promote chlamydia clearance in women.
Bacterial vaginosis is associated with higher rates of chlamydia persistence vs. spontaneous clearing, the Longitudinal Study of Vaginal Flora showed.
“We know from prior work that urogenital chlamydia can spontaneously clear without antibiotic treatment. Studies have recorded spontaneous clearance rates between 7% to 44% within the brief period between detection and treatment (commonly 1 to 2 weeks) and reaching up to 94% within a 4-year span,” Rebecca M. Brotman, PhD, MPH, professor in the department of epidemiology and public health at the University of Maryland School of Medicine, told Healio.
“The observation of natural clearance, combined with our rapidly expanding understanding of associations between the vaginal microbiome and risk of chlamydia infection, prompted us to explore the possible association between bacterial vaginosis (BV) and chlamydia persistence,” Brotman said.
According to Brotman, in most reproductive-age women, the vaginal microbiome is dominated by Lactobacillus species. However, she explained that approximately a quarter to a third of women experience BV, which is characterized by low Lactobacillus levels and a microbiome dominated by a variety of anaerobes.
“Lactobacilli are thought to protect against cervicovaginal infections, primarily due to their production of lactic acid, which defends against infectious agents,” she said. “BV has been associated with an increased risk of acquisition of a variety of sexually transmitted infections, including chlamydia.”
Through the Longitudinal Study of Vaginal Flora, which took place between 1999 and 2003, researchers tracked the cervicovaginal health of more than 3,000 women every 3 months across a 1-year period, during which baseline chlamydia screening and treatment were initiated after ligase chain reaction testing became available mid-study, and unscreened endocervical samples were tested after the study was closed.
Brotman and colleagues then used these data to retrospectively examine instances of untreated chlamydia to determine rates of clearance and persistence, as well as the associations between Nugent score (0-3, no BV; 4-10, intermediate/BV), Amsel-BV, and chlamydia persistence vs. clearance.
Overall, 431 patients contributed 630 index visits with no documented chlamydia treatment, of which 310 (48%) spontaneously cleared within the next 12 weeks, whereas 320 (52%) persisted at the next visit.
Participants with untreated chlamydia and an intermediate (4-6) or BV (7-10) index visit Nugent score had 1.7-fold (95% CI, 1.1-2.81) and 1.9-fold (95% CI, 1.32-2.89) higher odds of chlamydia persistence vs. spontaneous clearance by the next visit, compared with participants with a low Nugent score (0-3) in adjusted models. These results were similar for patients with Amsel-BV who had a 1.4-fold (aOR = 1.39; 95% CI, 0.99-1.96) higher odds of persistence vs. spontaneous clearance at the next visit.
Although Brotman said that these data are not clinically actionable at this time, the results are intriguing and indicate that a better understanding of the relationship between the vaginal microenvironment (including BV and the vaginal microbiome) and spontaneous clearance of chlamydia is a research priority.
She explained that in women, chlamydia infections are predominantly asymptomatic, and therefore, female patients usually do not seek care for infection, which is dangerous because untreated, persistent chlamydia in women can lead to significant sequelae such as infertility and pelvic inflammatory disease.
“Unfortunately, despite national guidelines to screen all sexually active women under age 25 years at least annually, rates of chlamydia infection remain unacceptably high. New interventions are needed to prevent chlamydia in women,” she said. “Understanding the complex factors including host, pathogen, and microbiome factors that lead to spontaneous clearance of chlamydia could, in the long term, inform the development of novel biotherapeutics, such as probiotics, to prevent chlamydia, facilitate chlamydial clearance and improve reproductive health.”
Brotman added, “The potential to harness the body's natural defense mechanisms to fight disease represents an exciting frontier in the field of sexually transmitted infections.”
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