Multicenter Evaluation of the BDProbeTec ET System in Detecting Chlamydia trachomatis and Neisseria gonorrhoeae from Endocervical and Urine Specimens in Women

INTRODUCTION The most prevalent sexually transmitted disease in the United States today is caused by Chlamydia trachomatis and the number of reported cases continues to rise. During 1998 the nation has experienced the first increase in the number of reported cases of gonorrhea following a several year decline in reported cases. The significance of serious complications related to chlamydia and gonorrhea infections has been well established. Urethritis, epididymitis, proctitis, cervicitis, pelvic inflammatory disease, infant pneumonia, and conjunctivitis are some of the potential outcomes of infection with these diseases. The advent of managed care and shrinking public health budgets have made rapid early accurate diagnosis and adequate treatment even more critical. The capability of testing using noninvasive specimens such as urine and the ability to acquire specimens in non-traditional venues has been reported as an important intervention effort. 4) Traditional cell culture methods have been the gold standard for diagnosis of chlamydia infections. However, cell culture methods are expensive, time consuming and subject to lab-to-lab variation. The introduction of enzyme immunoassay (EIA) tests and the DNA probe test (Gen-Probe, Inc.) for direct detection of antigen in patient samples provided an alternative to tissue culture. The sensitivity and specificity of EIA and DNA probe tests are comparable to culture. Recently, nucleic acid amplification methods based on the polymerase chain reaction (PCR), ligase chain reaction (LCR) and transcription mediated amplification (TMA) assays have been reported to offer improved performance over culture and other nonculture methods. 7, 8) These tests have expanded the capability for obtaining non invasive specimens in non-traditional settings. The latest amplified procedure to be evaluated in the United States is the Becton Dickinson BDProbeTecTM ET (BDPT) assay. The BDPT assay utilizes strand displacement amplification (SDA) to simultaneously amplify and detect Chlamydia trachomatis and Neisseria gonorrhoeae deoxyribonucleic acid (DNA) in male urethral swab and urine specimens and female endocervical and urine specimens. The purpose of this study was to assess the performance characteristics of the BDPT assay with female endocervical swab and first catch urine (FCU) specimens in a low prevalence population. The BDPT assay performance was compared to a gold standard, which compared BDPT to standard culture methods for CT and GC. The BDPT assay performance was further compared to an “enhanced” gold standard defined as a laboratory diagnosis of infection based upon the combined criteria of culture, direct fluorescent antibody testing of the spun down portion of the CT transport media, GC culture confirmation, and another nucleic acid amplification test (LCR).