The Diagnostic Discriminative Power of Serum IL-6 Levels for Chlamydia Trachomatis Infection

Background: Chlamydia trachomatis represents one of the most prevalent sexually transmitted infections, frequently persisting without noticeable symptoms, yet capable of leading to adverse outcomes such as infertility. The identification of reliable biomarkers has been emphasized as essential for enhancing early detection strategies. Objective: This research was conducted to evaluate the potential utility of circulating interleukin-6 (IL-6) as a biomarker for the diagnosis of Chlamydia trachomatis infection. Methods: A case–control approach was adopted, comprising 52 individuals with laboratory-confirmed C. trachomatis infection and 48 apparently healthy participants serving as controls. Serum IL-6 levels were quantified using the enzyme-linked immunosorbent assay (ELISA). Group differences were examined through independent samples t-tests, while variations associated with different infection sites were assessed using analysis of variance (ANOVA). Additionally, the diagnostic performance of IL-6 was evaluated via receiver operating characteristic (ROC) curve analysis to determine its accuracy in distinguishing infected from non-infected subjects. Results: Patients had significantly elevated IL-6 levels (18.6 ± 5.2 pg/ml) compared to controls (12.4 ± 4.1 pg/ml, p < 0.03). Analysis of serum IL-6 levels across different anatomical infection sites indicated that concentrations were highest in urogenital infections (19.2 ± 5.1 pg/ml), whereas rectal infections exhibited moderately lower values (17.5 ± 4.6 pg/ml). The area under the curve (AUC) was 0.84, with an optimal diagnostic threshold determined at 15.5 pg/ml, yielding a sensitivity of 80.8% and specificity of 77.1%. These findings suggest that IL-6 levels are markedly elevated in individuals affected by Chlamydia trachomatis, supporting its potential role as a reliable biomarker, particularly for urogenital infection sites.