Nucleic Acid Stability in Urine Samples
Explore the stability of gonococcal and chlamydial nucleic acids in urine samples stored under different conditions for a period of 25 days. Results show concentrations and detection of RNA and DNA over time. Implications for molecular diagnostics discussed.
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Presentation Transcript
A Question of Stability. Stability of GC and CT nucleic acids in Urine Hemanti Patel National Infections Services, Public Health England July 2016
Background Preliminary work for feasibility study see talk Logistics of home sampling for 35 days collection, storage and delivery Swabs stored at 2-30 C Urines - stored at 2-30 C but transferred within 24 hours Modified from http://biotechmedical.com.my/molecular-diagnostic/ 2 A Question of Stability
The Urine Stability experiment Aim An investigation was undertaken to determine the stability of gonococcal and chlamydial nucleic acids within urines samples stored in different conditions over a period of 25 days Variables 3 concentrations of gonococcal and chlamydial nucleic acids Temperature Refrigeration Room temperature Time Collected on days 1, 4, 8, 11, 18, 22 and 25 Detection RNA Hologic Panther system DNA In house reference laboratory PCR 3 A Question of Stability
Results CT RNA and DNA Results Room temperature 4 C Concentration 158 copies/reaction Concentration 24 copies/rxn Concentration 1 copies/rxn Concentration 158 copies/reaction Concentration 24 copies/rxn Concentration 1 copies/rxn Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive DAY 1 DAY 4 DAY 8 DAY 11 DAY 15 DAY 18 DAY 22 DAY 25 DAY 28 Insufficient DAY 31 Insufficient Insufficient Insufficient DAY 33 Insufficient Insufficient Insufficient Insufficient Insufficient Insufficient 4 A Question of Stability
Results GC RNA and DNA Results Room temperature 4 C concentration: 2.225x10^3 CFU/ML concentration: 2.225x10^2 CFU/ML concentration: 2.225x10^1 CFU/ML concentration: 2.225x10^3 CFU/ML concentration: 2.225x10^2 CFU/ML concentration: 2.225x10^1 CFU/ML Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive +- Positive Positive Positive Positive Positive Positive Positive Positive Positive Positive +- -eq Equivocal Eq- Positive Positive Positive Positive Positive Positive Positive Positive Positive Eq+ Positive +- Positive Positive Positive Positive Positive Positive Positive Positive +eq +- +- +eq +- +eq DAY 1 DAY 4 DAY 8 DAY 11 DAY 15 DAY 18 Negative Negative Negative DAY 22 DAY 25 DAY 28 +- DAY 31 Insufficient DAY 33 Insufficient Insufficient Insufficient Insufficient Insufficient Insufficient 5 A Question of Stability
Results - Summary Chlamydia RNA and DNA remained stable for over three weeks when either refrigerated or stored at room temperature. Gonorrhoea RNA and DNA remained stable for 11 days when stored at 4C When stored at room temperature was only reliably detectable at high concentrations. 6 A Question of Stability
Conclusions Chlamydial and gonococcal nucleic acids are stable in urine for longer than recommended by the manufacturer Patients should be encouraged to return their urine samples as soon as possible after collection to minimise the degradation of nucleic acids which could lead to false negative results. 7 A Question of Stability
Acknowledgments Professor Catherine Ison Dr Sarah Alexander Dr Binta Sultan Dr Gabriel Schembri Dr Paul Benn Conflict of interest HP received support from Hologic to attend this meeting. Hologic had no involvement in the design, analysis or presentation of this study. 8 A Question of Stability
