Guidance on storing specimens to enable enhanced surveillance
Updated 11 April 2024
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It is recommended to store all C. difficile toxin-positive faecal samples routinely to maximise the opportunity for outbreak investigation of CDI.
Storage will maximise availability of samples required for targeted outbreak investigation or local surveillance (particularly once there is a suspicion that the local picture has changed).
It is recommended to store C. difficile toxin-positive faecal samples at either 4°C or -20°C (1, 2).
The faecal samples can be stored conveniently in the original diagnostic specimen container – no additional broth or beads are necessary. (C. difficile will survive in refrigerated or frozen specimens, even following multiple freeze-thaw cycles (1)).
Please note: C. difficile toxins are degraded by freeze-thawing – if it is likely that faecal samples might need to be re-toxin-tested locally, these are best refrigerated at 4°C.
References
1. Department of Health and Public Health Laboratory Service Joint Working Group. ‘Clostridium difficile infection: prevention and management’ BAPS 1994: page 27 (last accessed 19 June 2007)
2. Freeman J, Wilcox MH. ‘The effects of storage conditions on viability of Clostridium difficile vegetative cells and spores and toxin activity in human faeces’ Journal of Clinical Pathology 2003: volume 56, pages 126 to 128