Improving influenza pre-analytic collection systems: alternative collection systems to inactivate, preserve, or extract influenza for rapid testing
Abstract number: O499
Castriciano S., Luinstra K., Ackerman M., Petrich A., Smieja M.
Objectives: In this study, 3 alternative influenza sample collection systems were evaluated for potential use in a pandemic situation. The objectives were to develop: 1) a non-temperature dependent swab collection and transport system, that inactivates influenza virus infectivity but preserves cell morphology and nucleic acid (NA) for the detection of suspected influenza infections and/or 2) a system compatible with direct NA testing without the need for purification prior to detection by a rapid real-time RT-PCR.
Methods: Flocked nasopharyngeal swabs (NPS) collected in UTM (U) were compared to NPS collected in a CyMol (C), M-swab (M) or Dry (D) Flocked Swab collection system (Copan, Italia). CyMol is an alcohol-based medium that preserves cells for DFA testing. The M-swab contains 600 uL of medium and 150 uL of glass beads, and requires no NA purification step. Shell vial culture was used to assess influenza virus inactivation after 30 minutes exposure to the collection media. A mock-infected Influenza A virus sample was absorbed to duplicate swabs then placed into the 4 collection systems. The infected collection media were held at RT for 30 minutes and then inoculated in duplicate into shell vial culture and stained after 48 hours. Influenza A stability and NA recovery after mock infection of each collection system was assessed after 1, 7, 14 and 21 days (d) at 4°C, -20°C, room temperature (RT) and 37°C. Aliquots of infected collection media were extracted by easyMag and 5 uL of purified NA tested by a quantitative influenza A RT-PCR on the Roche LightCycler. M-Swab collected samples were also tested directly or after boiling, without NA purification.
Results: Shell vial culture found that Influenza A virus was inactivated after 30 minutes exposure to the C medium but not when exposed to the U and M media. Influenza A was detected by DFA from the U and C cell smears. Quantitation of Influenza A RNA was constant after 1, 7 and 14 d in U, C, M and D collection systems at -20, 4°C and RT. The quantity of RNA recovered declined significantly after 14 d at 37°C in all 4 collection systems. M with boiling yielded data comparable to the easyMag extraction.
Conclusions: The Copan CyMol medium inactivates influenza infectivity, preserves cells and stabilises RNA up to 14 days at -20, 4°C and RT. CyMol medium is a potential alternative for safe sample collection during a pandemic influenza situation. The M-swab presents a rapid testing alternative.
|Session name:||19th European Congress of Clinical Microbiology and Infectious Diseases|
|Location:||Helsinki, Finland, 16 - 19 May 2009|
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