Comparative Evaluation of ELISA and PCR for Chlamydia trachomatis Diagnosis in HIV Patients: Implications for Screening in Resource-limited Settings

Abstract

Background: Chlamydia trachomatis, a prevalent and often asymptomatic global STI, leads to severe reproductive health complications if undiagnosed. Accurate diagnosis is vital for control, but cost and infrastructure limit highly sensitive NAATs like PCR in resource-constrained settings. ELISA offers an affordable alternative, yet its diagnostic performance, particularly in distinguishing active from past infections, requires evaluation. This study compared ELISA and PCR for C. trachomatis detection in Owerri, Nigeria, assessing implications for screening in resource-limited contexts. Methods: A cross-sectional study was conducted on 518 participants (318 symptomatic, 200 asymptomatic) in Owerri, Nigeria. Serum samples were tested for C. trachomatis IgG antibodies using ELISA, while swab samples were analyzed for C. trachomatis DNA by PCR, serving as the reference standard. A comparative analysis of ELISA and PCR results was performed on a subset of 40 samples to determine ELISA's sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Results: Overall, both ELISA and PCR detected C. trachomatis in 35 (6.8%) participants. However, on the 40-sample subset, ELISA demonstrated a high sensitivity of 92.9% but a low specificity of 27.3%. The PPV was 74.3%, and the NPV was 40.0%. This indicates that while ELISA was effective at identifying most true positives, it yielded a significant number of false positives and had limited ability to reliably rule out infection. Conclusion: ELISA shows high sensitivity for C. trachomatis antibody detection, but its low specificity and negative predictive value limit its standalone use for active screening due to inability to differentiate past from current infections. PCR and other NAATs remain superior for active diagnosis. Integrated strategies or investment in accessible NAATs are crucial for effective C. trachomatis control in resource-limited settings.