Prevalence of Chlamydia trachomatis infection among women in a multiphysician primary care practice.

Abstract

I screened 312 women, 18-45 years of age, presenting for routine gynecologic examination or prenatal care in a multiphysician primary care practice for Chlamydia trachomatis and Neisseria gonorrhoeae. I evaluated age, pregnancy, payment status, and presence of clinical cervicitis or gonorrhea as possible predictors of risk for chlamydial infection. Compared to culture, the direct immunofluorescent antibody (DFA) test used to screen for C trachomatis had a sensitivity of 70% and a specificity of 97%. By culture, the overall prevalence of chlamydial infection was 3.2% (confidence limits [CL] = 1.1-5.9) with a prevalence of 2.2% in nonpregnant women and 9.3% in pregnant women. Overall prevalence by the DFA test was 5.45%. Pregnancy status and youth were the significant predictors of risk for infection as determined by culture but not by Microtrak. Payment status, clinical cervicitis, and gonorrhea cultures were not useful predictors of increased risk. I discuss the implications of using culture, an imperfect "gold standard," for determining sensitivity, specificity, and prevalence.