P377 Chlamydia trachomatis and Neisseria gonorrhoeae DNA stability in preserved first-void urine

Abstract

<h3></h3> The aim of this study was to evaluate the performance of UCM (Urine Conservation Medium, Novosanis) for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) DNA preservation at room temperature (RT). To compare the stability of CT and NG DNA in unpreserved and UCM-preserved samples, five urine samples were spiked to obtain 99 CT and 75.5 NG DNA copies/µL in the final aliquot. For UCM-preserved samples, UCM was spiked and urine was added in a 2:1 (urine:UCM) ratio to mimic real-life use of Colli-Pee containing UCM. A total of 30 aliquots were analyzed using the Abbott Real-Time CT/NG assay after storage at RT for 1, 8 and 15 days. Mixed-effect regression analysis was used to estimate the effect of UCM on CT and NG Ct values at each timepoint, with urine samples as random effects. After 15 days of storage, all UCM-preserved samples were positive for CT and NG, while only one and three unpreserved samples remained positive for CT and NG respectively. Ct values where samples were negative for CT and/or NG were defined as the cut-off values (cut-off 8d: CT=39.66, NG=39.93; cut-off 15d: CT=39.56, NG=39.92). At each timepoint, Ct-values for CT and NG were significantly lower for preserved compared to unpreserved samples. At 1, 8 and 15 days of storage UCM-preserved samples showed an estimated differences of -6.03, -5.91 and -4.60 cycles for CT, and -6.91, -7.20 and -7.36 for NG respectively. All effects are statistically significant with p&lt;0.01. UCM-preserved urine sampling enables preservation of CT and NG DNA for 15 days of storage at RT. The use of Colli-Pee, whereby the collector tube is prefilled with UCM, allows for immediate mixing of urine and preservative. This offers opportunities for home-based testing where sample quality is maintained during storage and sample shipment to the laboratory by regular postal mail.