Contrary to current convention by which infection with the organism Clostridium difficile is regarded as an infection that is acquired by contact with symptomatic patients known to be infected with C. difficile, these may account for only a minority of new cases of the infection. These findings are important as they indicate that C. difficile infection, which can be fatal especially in older people, may not be effectively controlled by current hospital infection strategies.
In a study led by Professor Tim Peto of the John Radcliffe Hospital in Oxford, UK, and published in this week's PLoS Medicine, almost 30 000 stool samples from nearly 15 000 patients were tested for C. difficile, with 4.4% (n=1282) found to be positive by specialised laboratory tests (enzyme immunoassay and culture). With further tests (genotyping), the researchers identified 69 types of C. difficile and when linking this information to the clinical situation found that the majority of cases of C. difficile infection were not linked to known cases (66%) and only 23% shared the same type of C. difficile as a ward patient known to be infected.
The authors say: "In this endemic setting with well-implemented infection control measures, up to three-quarters of new [C.difficile infections] are not easily explained by conventional assumptions of ward-based transmission from symptomatic patients and so may not be targeted by current interventions."
The authors conclude: "A better understanding of other routes of transmission and reservoirs is needed to determine what other types of control interventions are required to reduce the spread of C. difficile."
However, in an accompanying Perspective article, Stephan Harbarth from the University of Geneva Hospitals and Medical School in Switzerland and Matthew Samore from the University of Utah School of Medicine in Salt Lake City, USA (uninvolved in the research study) note that given the methods used in the study, the research cannot definitively answer some important clinical questions, such as the amount of benefit accrued by blocking transmission from symptomatic C. difficile infection cases and the proportion of the C. difficile infections that are attributed to within-hospital transmission that actually represent already-infected individuals who come into the hospital. Harbarth and Samore say: "The study by Sarah Walker and colleagues cannot provide definitive answers to these questions because it has significant limitations with respect to both issues." These authors recommend that more studies be conducted to fully answer these questions.
Article by Walker et al.
Funding: This work was supported by both the Oxford NIHR Biomedical Research Centre and the UKCRC Modernising Medical Microbiology Consortium, with the latter being funded under the UKCRC Translational Infection Research Initiative supported by Medical Research Council, Biotechnology and Biological Sciences Research Council, and the National Institute for Health Research on behalf of the Department of Health (Grant G0800778) and The Wellcome Trust (Grant 087646/Z/08/Z). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The institution of DWC and TEAP received per-case funding from Optimer Pharmaceuticals to support fidaxomicin trial patient expenses. DWC and TEAP also received honoraria from Optimer Pharmaceuticals for participation in additional meetings related to investigative planning for fidaxomicin. MHW has received honoraria for consultancy work, financial support to attend meetings and research funding from bioMerieux, Optimer, Novacta, Pfizer, Summit, The Medicines Company, and Viropharma. All other authors have declared that no competing interests exist.
Citation: Walker AS, Eyre DW, Wyllie DH, Dingle KE, Harding RM, et al. (2012) Characterisation of Clostridium difficile Hospital Ward-Based Transmission Using Extensive Epidemiological Data and Molecular Typing. PLoS Med 9(2): e1001172. doi:10.1371/journal.pmed.1001172
National Institute for Health Research
Oxford Biomedical Research Centre
John Radcliffe Hospital
Perspective by Stephan Harbarth and Matthew Samore
Funding: This article was supported in part by the 7th Framework Programme of the European Community in the context of the project ''Impact of Specific Antibiotic Therapies on the Prevalence of Human Host Resistant Bacteria'' (acronym SATURN, FP7-HEALTH-2009 contract Nu241796). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
Citation: Harbarth S, Samore MH (2012) Clostridium: Transmission difficile? PLoS Med 9(2): e1001171.doi:10.1371/journal.pmed.1001171
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University of Geneva Hospitals and Medical School
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