Screening for Chlamydia trachomatis infection in women and aspects of the laboratory diagnostics.

Nine hundred and thirty-three women who attended consecutively a gynecological clinic for various symptoms, for abortion, or for contraceptives, were screened for genital Chlamydia trachomatis infection. A total of 95 (10.2%) women were found infected. Of women below 25 years of age, 13.4% were infected, as compared with 4.9% over 25. Women with symptoms of genital infection were not over-represented in the infected population. Enzyme immunoassays (EIA) verified with a direct fluorescence antigen test were evaluated and compared with culture controls. Reactive samples detected using EIA were regarded as true positive if they were also positive according to the verification test. The sensitivity of the verified EIA test was 91%, the specificity 100%, the positive predictive value 100% and the negative predictive value was 99%. The sensitivity of the culture was 90%. Low age is the most predictable risk factor for genital Chlamydia trachomatis infection. Compared with cultures, EIA verified with a direct fluorescence antigen test is a rapid and effective method for clinical use.