Magic Lite Chlamydia immunoassay in urogenital samples and urine versus chlamydial culture

Magic Lite Chlamydia assay (commercial test kit for the identification of Chlamydia trachomatis) was evaluated on urogenital samples and urine with chlamydial culture as the reference method. The sediment of the transportation buffer of specimens which were Magic Lite positive but culture negative or toxic was investigated for elementary bodies with fluorescein-labelled anti-chlamydial antibodies. The prevalence of chlamydial infection among the 577 men investigated was 13.7% as estimated by culture and direct immunofluorescence and 6.4% among the 173 women. In order to improve the sensitivity a cut-off value below that recommended by the manufacturer was used. The sensitivity of Magic Lite in male urethral specimens was then 60.8% and that in female urethral/cervical specimens 90.9%. The specificity was 99.6% and 100%, respectively. In urine specimens the sensitivity of Magic Lite was 63.3% (men) and 63.6% (women). The specificity was 99.4% and 100%, respectively. The sensitivity of Magic Lite on male urethral specimens was related to the number of inclusion bodies per well in culture and it was higher among men attending with clinical findings of urethritis (69%) than among asymptomatic men sampled as a screening procedure (36%) (P < 0.05). Corresponding differences between the sexes and between those with and without symptoms were not noted for Magic Lite applied on urine samples.