A-296 Streck Urine Preserve Provides Sample Stability for Cepheid Xpert CT/NG test

Abstract Background Sexually transmitted infections (STIs) are one of the most common communicable diseases worldwide and are associated with significant morbidity and mortality. Data indicates that the four curable STIs - chlamydia, gonorrhea, trichomoniasis, and syphilis - cause over 375 million infections annually. Further, the infection rate for gonorrhea has increased by 63% in the United States and the emergence of resistant gonorrhea is an urgent global public health concern. To prevent transmission of gonorrhea and other curable STIs and minimize the escalation of untreated infections, early and effective prevention and control strategies are paramount. Rapid diagnostic testing and nucleic acid amplification tests (NAATs) have become the gold standard for STI detection. However, limited global access to these technologies often requires that samples be shipped to central laboratories for analysis. Current protocols recommend that neat urine be analyzed within 24 hours of collection if stored at 2 °C to 8 °C or within four days if frozen, as prolonged storage and exposure to freeze-thaws can induce cell lysis and release of nucleases, leading to degradation of DNA and false negative test results. Without sample stabilization, laboratories are left with a small window for accurate analysis. Here, we demonstrate that Streck Urine Preserve (SUP) maintains target and donor DNA concentrations during prolonged storage and that these stabilized samples are compatible with Cepheid’s automated GeneXpert System and associated Xpert CT/NG test. Methods Fresh human urine, with or without SUP, was tested neat or spiked with Neisseria gonorrhoeae (N. gonorrhoeae). Samples were stored at room temperature for up to 18 days before being analyzed on the Cepheid GeneXpert System using the Xpert CT/NG test per manufacturer’s instructions. Differences in average Ct values were compared for the sample processing control, sample adequacy control, and N. gonorrhoeae targets. DNA stability was assessed by comparing the changes between fresh and SUP-treated samples throughout the study period. Results Following prolonged storage, Ct values for neat, untreated urine increased by 3-7 cycles, correlating to a 10- to 100-fold decrease in detectable copies of N. gonorrhoeae and the sample adequacy control compared to urine samples stabilized with SUP. The average Ct value for samples stabilized with SUP did not change by more than 1.5 cycles throughout the study period. Additiona