Contribution of the ELISA and PCR tests in the diagnosis of Chlamydia trachomatis infection in fertile and infertile women in resource-limited settings: a case-control study

Abstract

Background and Purpose: Chlamydia trachomatis (CT) is the most common infectious cause of infertility. It can be diagnosed using several techniques. Most tests are performed using ELISA and this leads to an excessive intake of antibiotics. The aim was to compare the frequency of CT infection in infertile and fertile women submitted to ELISA and PCR tests, and to determine the sensitivity and specificity of ELISA for current infection.
Methods: We carried out a case-control study over a period of seven months. Patients with infertility (cases) and with confirmed pregnancy (controls) were included in the study after giving their informed consent. Data collected included sociodemographic characteristics, past medical history, clinical examination, ELISA test (IgG, and IgM) and PCR test for Chlamydia. Chi-square, Fisher’s and Student’s tests were used to explore associations between variables.
Results: Two hundred patients, 100 fertile and 100 infertile, were enrolled. The ELISA test was positive in 34.3% of the infertile women as compared with 12.5% of the fertile women (OR:3,652 [1,135-11,749]). The PCR test was positive in 8% of the cases and 8% of the controls. On multivariate analysis, low monthly income, cervical motion tenderness and adnexal mass were found to be independent predictors of infertility. Considering PCR as the reference test, ELISA showed lower sensitivity in the diagnosis of CT. However, IgM had better specificity. The association of a positive IgM test with clinical signs predicted the diagnosis of current CT infection in 81.3% of cases.
Conclusion: The proportion of CT seropositivity (IgG and IgM) was higher in infertile than fertile women. No difference in PCR positivity was found between the two groups. It is important to raise awareness, among women, of the influence of this infection on their fertility and to carry out PCR tests to identify patients to whom treatment should be given.