Detection of bacterial vaginosis-associated bacteria and outcomes during clinical gynaecological conditions using qPCR: A retrospective cohort study

Endometriosis, chronic endometritis (CE), unexplained infertility (UI), and recurrent pregnancy loss (RPL) are gynecological conditions frequently associated with inflammation and alterations in the endometrial microbiome. The presence of bacterial vaginosis-associated bacteria (BVAB) and the expression of CD138 may influence clinical outcomes. We evaluate the relationship between endometrial BVAB detection via qPCR, CD138 marker expression, prior antibiotic treatment, and the number of miscarriages. A retrospective single-center cohort study was conducted on 86 women with endometriosis, CE, UI, and/or RPL. Endometrial samples were collected and analysed using the Allplex™ Bacterial Vaginosis Plus qPCR assay (Seegene^Ⓡ). Demographic data, CD138 expression, antibiotic usage, and miscarriage history were recorded and statistically analysed. CD138 expression was positive in 44.2% of cases. BVAB were detected in 31.4% of patients, with Lactobacillus spp. (median Log₁₀ copies/reaction 1.56) and G. vaginalis (median Log₁₀ copies/reaction 0.81) being the most common. A significant inverse association was found between CD138 positivity and BVAB detection (p < 0.05, OR = 0.31), suggesting reduced BVAB presence in inflamed endometria. No significant association was found between BVAB detection and prior antibiotic therapy or number of miscarriages. A significant correlation was found between negative BVAB qPCR results and positive CD138 expression, indicating a potential link between endometrial inflammation and microbiome alterations. However, antibiotic treatment did not significantly impact BVAB presence, and no association was found with miscarriage frequency. Further studies using vaginal swabs, healthy controls, and microbiome next-generation sequencing are needed to clarify these associations.