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J Med Microbiol. 2018 May;67(5):631-640. doi: 10.1099/jmm.0.000719. Epub 2018 Mar 13.

Clostridium difficile shows no trade-off between toxin and spore production within the human host.

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1​Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA.
2​Department of Microbiology and Immunology, College of Letters & Science, Montana State, Bozeman, Montana, USA.
3​Department of Infection Prevention and Control, Department of Internal Medicine, Division of Infectious Diseases, St Joseph Mercy Health System, Ann Arbor, Michigan, USA.
4​Department of Pathology, Microbiology Laboratory, St Joseph Mercy Health System, Ann Arbor, Michigan, USA.
5​Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA.



This study aimed to describe the correlation between Clostridium difficile spore and toxin levels within the human host. In addition, we assessed whether overgrowth of Candida albicans modified this association.


We measured toxin, spore and Candida albicans levels among 200 successively collected stool samples that tested positive for C. difficile, and PCR ribotyped these C. difficile isolates. Analysis of variance and linear regression were used to test the association between spore and toxin levels. Kruskal-Wallis tests and t-tests were used to compare the association between spore or toxin levels and host, specimen, or pathogen characteristics.


C. difficile toxin and spore levels were positively associated (P<0.001); this association did not vary significantly with C. albicans overgrowth [≥5 logs of C. albicans colony-forming units (c.f.u.) g-1]. However, ribotypes 027 and 078-126 were significantly associated with higher levels of toxin and spores, and C. albicans overgrowth.


The strong positive association observed between in vivo levels of C. difficile toxin and spores suggests that patients with more severe C. difficile infections may have increased spore production, enhancing C. difficile transmission. Although, on average, spore levels were higher in toxin-positive samples than in toxin-negative/PCR-positive samples, spores were found in almost all toxin-negative samples. The ubiquity of spore production among toxin-negative and formed stool samples emphasizes the importance of following infection prevention and control measures for all C. difficile-positive patients during their entire hospital stay.


Clostridium difficile infection; spores; toxin

[Indexed for MEDLINE]

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