Detection of Chlamydia trachomatis in adolescent females using direct immunofluorescence

Direct immunofluorescent slide tests for the detection of genital Chlamydia trachomatis have attracted considerable attention because of their speed and economy, but most evaluation trials have concentrated on adult, high-risk populations. Using 152 paired specimens, we compared the Syva Micro Trak direct specimen test with culture in a population of adolescent females attending a general adolescent medicine clinic. The direct slide test was 90 percent sensitive and 95 percent specific overall, with positive and negative predictive values of 74 percent and 98 percent, respectively. Prevalence by culture was 13 percent. Six of our 23 positive slide tests could not be confirmed by culture. A positive chlamydia culture was significantly associated with nonwhite race, a positive Gram's stain, and the presence of mucopurulent endocervical discharge, but not with oral contraceptive pill use, obstetrical history, Pap smear results, multiple sexual partners, coexisting vaginitis or gonorrhea, or a history of prior sexually transmitted diseases. The direct test appears to be an acceptable substitute for culture in higher prevalence adolescent settings and a useful screening adjunct in lower prevalence groups.