Automated Sample-to-Results Analysis of Clinical Specimens for Sexually-Transmitted Infections

Introduction/Background The global burden of sexually- transmitted infections (STIs) is considerable with an estimated 340 million new cases occurring each year. Although many of these new cases could potentially be effectively cured with modern antibiotic therapy, the early stages of the infections can often go unnoticed. Females are disproportionately affected, in whom untreated STIs can proceed to disabling pelvic inflammatory disease which, in turn, can lead to infertility, infant mortality, and infant blindness. Complications in untreated males, although rarer, can proceed to urethritis, epididymitis, and infertility. In order to streamline testing, we have developed a fully automated molecular detection system to simultaneously detect N. gonorrhoeae (NG), C. trachomatis (CT), and T. vaginalis (TV) in an unattended manner from a variety of specimens. Materials and Methods An injection-molded disposable CARD® (Chemistry & Reagent Device) cartridge was developed that, when inserted into the EncompassMDx™ Workstation, can automatically lyse cells, extract and purify DNA, and multiplex PCR amplify rRNA genomic targets in NG and TV and cryptic plasmid DNA of CT. In order to confirm that all steps of the assay were performed correctly by the system, three separate chimeric plasmids were designed that harbor unique DNA sequences that can be amplified by the same primer pair sets designed to amplify the individual targets of CT, NG, and TV. Hybridization of the control amplicons can be detected and distinguished from hybridization of target amplicons on the integrated DNA array. Results Several different clinical reference laboratories provided us with approximately 100 diverse specimens (vaginal swabs, endocervical swabs, and urine specimens), previously tested using FDA-cleared devices in their facilities. Evaluation of the same samples with the Rheonix STI Tri-Plex Assay* yielded similar results. Moreover, since the FDA-cleared reference