Cytologic manifestations of cervical and vaginal infections. II. Confirmation of Chlamydia trachomatis infection by direct immunofluorescence using monoclonal antibodies.

We found inflammatory patterns of transparent lymphocytes on increased numbers of histiocytes suggestive of chlamydial infection in 68 (56%) of 121 cervical cytologic smears. Chlamydia trachomatis was isolated from 36 (53%) of those with and only two (4%) of those without such inflammatory patterns. Direct stain with fluorescein-conjugated monoclonal antibodies demonstrated elementary bodies of C trachomatis in 30 (79%) of the 38 culture-positive patients, including 29 of the culture-positive patients who had an inflammatory cytologic pattern suggestive of C trachomatis infection. Thus, Papanicolaou smears can be screened for inflammatory pattern, and separate endocervical smears from patients with a pattern suggestive of chlamydial infection can then be stained by immunofluorescence to confirm the presence of C trachomatis infection. This two-step approach detected 29 of 38 infections confirmed by culture in the present study, giving a sensitivity of 76%, a specificity of 100%, and a positive predictive value of 100% in a population having a 31% prevalence of C trachomatis infection.