A comparison of nonculture-dependent methods for detection of Chlamydia trachomatis infections in pregnant women

Abstract

Two nonculture-dependent methods for the detection of Chlamydia trachomatis in endocervical samples from obstetric patients were compared with routine isolation in McCoy cell cultures. When compared with culture, the sensitivities and specificities of the methods were: direct fluorescent antibody staining (MicroTrak [Syva Co.]) 98.1 and 95.4%, and enzyme immunoassay (Chlamydiazyme [Abbott Laboratories]) 96.3 and 92.9%, respectively. In 89% of apparent false-positive direct fluorescent antibody cases and 64% of enzyme immunoassay cases, an additional positive nonculture result was considered to indicate infection missed by culture. Considering these data, revised sensitivities were 84.4% for culture, 95.2% for direct fluorescent antibody, and 95.3% for enzyme immunoassay. Revised specificities were 99.5% for direct fluorescent antibody and 97.3% for enzyme immunoassay. Both nonculture tests appear acceptable for screening high-risk obstetric patients, and may be more sensitive than routine cell culture.