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Ocular Chlamydia trachomatis in a tertiary hospital
Chlamydia trachomatis, a leading cause of blindness, remains hyperendemic in the poorer regions of the world. In Egypt, the disease represents a major health problem. The objective was to assess the active trachoma and actual ocular C.trachomatis infection as diagnosed by its isolation in the Vero cell line followed by its detection using Giemsa stain, iodine stain, enzyme-linked immunosorbent assay (ELISA) and Gen-Probe. Forty patients clinically diagnosed with chlamydial conjunctivitis were collected from the outpatient clinic of the Ophthalmology Centre, Mansoura University Hospital, Egypt. Two scrapings were taken, one fixed onto a slide for direct Giemsa stain and the other transported on sucrose phosphate medium to be cultured on the Vero cell line then identified by Giemsa and iodine stains, ELISA and Gen-Probe. C.trachomatis was detected by direct Giemsa stain in 1/40 (2.5%) of samples but isolated in the Vero cell line and identified in 4/40 samples (10%) by Giemsa and iodine stains or Gen-Probe. However, ELISA identified only 2/40 (5%) of total samples after culture. Direct Giemsa stain provided low sensitivity (25%) and a high specificity (100%) compared with cell cultures, with high statistically significant differences between both tests (P-value<0.001). All the indices for Gen-Probe in relation to Giemsa stain for chlamydial identification after culture were 100%. Sensitivity, specificity, positive and negative predictive values (PPV and NPV, respectively) and efficiency of chlamydial culture identification by ELISA as related to Giemsa stain identification were 50%, 100%, 100%, 94.7% and 95%, respectively, with high statistically significant differences between both tests (P-value<0.001). C. trachomatis was detected in a relatively high rate of acute follicular conjunctivitis patients as detected with culture on the Vero cell line. Identification of C. trachomatis in culture was 100% by Giemsa and iodine stains or Gen-Probe but only 50% by ELISA. Direct Giemsa stain demonstrated low sensitivity (25%) and high specificity (100%).