Detection of Chlamydia trachomatis from genito-urinary specimens by improved nucleic acid sandwich hybridization

Nucleic acid sandwich hybridisation was applied to the detection of Chlamydia trachomatis directly from clinical specimens. In this study a combination of reagents was used, detecting both the genomic DNA and the cryptic plasmid of C. trachomatis. Thereby the sensitivity of the test was improved allowing detection of less than 10⁵ elementary bodies (EBs). The specimens (N = 268) were collected in an outpatient clinic for sexually transmitted diseases from female patients with cervicitis and from male patients with urethritis. The reference test was chlamydial isolation by cell culture. The sensitivity of the sandwich hybridization test was 77% (50/65) as compared with culture. In addition, 15% of the specimens remaining negative by culture were positive in hybridization (31/203). The high specificity of the test reagents has been proven and no background due to specimen impurities was observed. Therefore, detecting in this study 81 chlamydial infections as opposed to 65 detected by culture only, sandwich hybridization will offer a valuable supplement for the tests diagnosing C. trachomatis.