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Research Article

The Anti-Sigma Factor TcdC Modulates Hypervirulence in an Epidemic BI/NAP1/027 Clinical Isolate of Clostridium difficile

  • Glen P. Carter,

    Affiliation: Department of Microbiology, Monash University, Clayton, Victoria, Australia

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  • Gillian R. Douce,

    Affiliation: Division of Infection and Immunity, FBLS Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, United Kingdom

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  • Revathi Govind,

    Affiliation: Division of Biology, Kansas State University, Manhattan, Kansas, United States of America

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  • Pauline M. Howarth,

    Affiliation: Department of Microbiology, Monash University, Clayton, Victoria, Australia

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  • Kate E. Mackin,

    Affiliation: Department of Microbiology, Monash University, Clayton, Victoria, Australia

    X
  • Janice Spencer,

    Affiliation: Division of Infection and Immunity, FBLS Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, United Kingdom

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  • Anthony M. Buckley,

    Affiliation: Division of Infection and Immunity, FBLS Glasgow Biomedical Research Centre, University of Glasgow, Glasgow, United Kingdom

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  • Ana Antunes,

    Affiliation: Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France

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  • Despina Kotsanas,

    Affiliation: Department of Infectious Diseases, Southern Health, Monash Medical Centre, Clayton, Victoria, Australia

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  • Grant A. Jenkin,

    Affiliation: Department of Infectious Diseases, Southern Health, Monash Medical Centre, Clayton, Victoria, Australia

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  • Bruno Dupuy,

    Affiliation: Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France

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  • Julian I. Rood,

    Affiliation: Department of Microbiology, Monash University, Clayton, Victoria, Australia

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  • Dena Lyras mail

    Dena.Lyras@monash.edu

    Affiliation: Department of Microbiology, Monash University, Clayton, Victoria, Australia

    X
  • Published: October 13, 2011
  • DOI: 10.1371/journal.ppat.1002317

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BI/NAP1/027 strains are not more proficient at sporulation

Posted by davidaburns on 19 Oct 2011 at 18:31 GMT

Many BI/NAP1/027 strains are also more proficient at sporulation than non-epidemic C. difficile strains [12], [49]. C. difficile spores are highly infectious [50] and play a critical role in the transmission of CDI and perhaps in disease relapse, which is a serious problem in patients with CDI [51]. In this context, enhanced sporulation is ostensibly an important adaptation by BI/NAP1/027 isolates, which would result in larger numbers of spores being shed from infected patients and an increased environmental spore load, ultimately leading to higher transmission rates.
http://plospathogens.org/article/info:doi/10.1371/journal.ppat.1002317#article1.body1.sec3.p7

It must be considered that there are other studies present in the literature that have analysed the sporulation characteristics of "C. difficile" isolates, which the authors have elected not to discuss (1,2,3,4,5). Despite a general consensus within the field that BI/NAP1/027 strains are more prolific in terms of sporulation, two studies published prior to this article have provided credible evidence that the substantial diversity in sporulation rates among "C. difficile" clinical isolates does not correlate with the PCR-ribotype (1,2). The reason for these differing conclusions may reflect the experimental techniques used and concerns have been expressed over the limitations of some previous studies (6).

There are now an additional two published studies which, by using sample sizes far in excess of the previous studies, have shown that BI/NAP1/027 strains do not have an increased rate of sporulation (7,8). In addition, there is growing evidence that PCR-ribotype 078 strains have a somewhat low sporulation rate compared with clinical isolates of other types (7).

Given the evidence available in the literature, it does not seem prudent to state that BI/NAP1/027 strains are more proficient at sporulation than non-epidemic types and that increased sporulation rates are linked to higher transmission rates of CDI.

1. Burns DA, Heap JT, Minton NP (2010) SleC is essential for germination of "Clostridium difficile" spores in nutrient-rich medium supplemented with the bile salt taurocholate. J Bacteriol 192: 657–664.
http://jb.asm.org/cgi/content/full/192/3/657?view=long&pmid=19933358

2. Burns DA, Heap JT, Minton NP (2010) The diverse sporulation characteristics of "Clostridium difficile" clinical isolates are not associated with type. Anaerobe 16: 618–622.

3. Vohra P, Poxton IR (2011) Comparison of toxin and spore production in clinically relevant strains of "Clostridium difficile". Microbiology 157: 1343–1353.

4. Fawley WN, Underwood S, Freeman J, Baines SD, Saxton K, et al. (2007) Efficacy of hospital cleaning agents and germicides against epidemic "Clostridium difficile strains". Infection Control and Hospital Epidemiology 28: 920–925.

5. Wilcox MH, Fawley WN (2000) Hospital disinfectants and spore formation by "Clostridium difficile". Lancet 356: 1324.

6. Burns DA, Minton NP (2011) Sporulation studies in "Clostridium difficile". Journal of Microbiological Methods 87: 133–138.
http://www.sciencedirect.com/science/article/pii/S016770121100282X

7. Burns DA, Heeg D, Cartman ST, Minton NP (2011) Reconsidering the Sporulation Characteristics of Hypervirulent "Clostridium difficile" BI/NAP1/027. PLoS ONE 6(9): e24894. doi:10.1371/journal.pone.0024894
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0024894

8. Sirard S, Valiquette L, Fortier LC (2011) Lack of association between clinical outcome of "Clostridium difficile" infections, strain type, and virulence-associated phenotypes. J Clin Microbiol in press. doi:10.1128/JCM.05053-11

No competing interests declared.