Comparative evaluation of two diagnostic methods for the detection of chlamydia trachomatis in endocervical specimens

Context: Genital infections caused by Chlamydia trachomatis have been a significant healthcare problem recognized throughout the world in recent years. The World Health Organization estimates that approximately two million new cases of genital chlamydial infection occur annually in females. Objectives: The objective was to compare the performance of the glycogen assay test to the polymerase chain reaction (PCR) in the diagnosis of genital chlamydial infection. Materials and Methods: Consenting female patients were consecutively recruited for the study until the sample size of 365 was achieved. Two endocervical specimens were collected from each of the patients using sterile plastic-shaft Dacron swabs. C. trachomatis test kit (Autobio Company China) was used according to the manufacturer's instructions. The test is a biochemical assay for the detection of C. trachomatis in clinical samples taken from the genital tract. PCR was also done for each sample. Data management was done using the Statistical Package for the Social Sciences version 20.0. Results: Of the women studied, 95 (26%) were positive and 270 (74%) negative for genital chlamydial infection using the PCR, while 244 (66.8%) tested positive and 121 (31.2%) tested negative using the glycogen assay. Conclusions: With the results generated above and using the PCR as the standard, sensitivity for the glycogen assay was 86.3%, specificity was 40%, and the predictive value for a positive result was 33.6%, while that for a negative result was 89.3%. The glycogen assay kit is locally available, not expensive (compared to the very high cost of PCR) and often used in the diagnosis of genital chlamydial infection. However, with a sensitivity of 86.3% and specificity of 40% for the glycogen assay, found in this study, the test kit is far from ideal as a tool for the rapid diagnosis of genital C. trachomatis infection, as it will yield high numbers of false-positive results.