Pickering, DS, Vernon, JJ orcid.org/0000-0002-0072-9294, Freeman, J et al. (2 more authors) (2019) Investigating the transient and persistent effects of heat on Clostridium difficile spores. Journal of Medical Microbiology, 68 (10). pp. 1445-1454. ISSN 0022-2615
Abstract
Purpose: Clostridium difficile spores are extremely resilient to high temperatures. Sublethal temperatures are associated with the ‘reactivation’ of dormant spores, and are utilized to maximize C. difficile spore recovery. Spore eradication is of vital importance to the food industry. The current study seeks to elucidate the transient and persisting effects of heating C. difficile spores at various temperatures.
Methods: Spores of five C. difficile strains of different ribotypes (001, 015, 020, 027 and 078) were heated at 50, 60 and 70–80 °C for 60 min in phosphate-buffered saline (PBS) and enumerated at 0, 15, 30, 45 and 60 min. GInaFiT was used to model the kinetics of spore inactivation. In subsequent experiments, spores were transferred to enriched brain heart infusion (BHI) broths after 10 min of 80 °C heat treatment in PBS; samples were enumerated at 90 min and 24 h.
Results: The spores of all strains demonstrated log-linear inactivation with tailing when heated for 60 min at 80 °C [(x̄=7.54±0.04 log10 vs 4.72±0.09 log10 colony-forming units (c.f.u.) ml− 1; P<0.001]. At 70 °C, all strains except 078 exhibited substantial decline in recovery over 60 min. Interestingly, 50 °C heat treatment had an inhibitory effect on 078 spore recovery at 0 vs 60 min (7.61±0.06 log10 c.f.u. ml− 1 vs 6.13±0.05 log10 c.f.u. ml− 1; P<0.001). Heating at 70/80 °C inhibited the initial germination and outgrowth of both newly produced and aged spores in enriched broths. This inhibition appeared to be transient; after 24 h vegetative counts were higher in heat-treated vs non-heat-treated spores (x̄=7.65±0.04 log10 c.f.u. ml− 1 vs 6.79±0.06 log10 c.f.u. ml− 1; P<0.001).
Conclusions: The 078 spores were more resistant to the inhibitory effects of higher temperatures. Heat initially inhibits spore germination, but the subsequent outgrowth of vegetative populations accelerates after the initial inhibitory period.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2019 The Authors. This is an author produced version of a paper published in Journal of Medical Microbiology. The definitive peer reviewed, edited version of this article is published in Journal of Medical Microbiology, 2019, https://doi.org/10.1099/jmm.0.001048. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | broth enrichment; C. difficile; heat activation; heat treatment; spores |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Medicine and Health (Leeds) > School of Dentistry (Leeds) > Oral Biology (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 12 Sep 2019 13:17 |
Last Modified: | 21 Oct 2019 21:20 |
Status: | Published |
Publisher: | Microbiology Society |
Identification Number: | 10.1099/jmm.0.001048 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:150730 |
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