It has been a widely held belief that most C. difficile infections are spread in hospital from a case with active disease to other patients.
A recent study, funded by the National Institute of Health Research, in Oxford and Leeds however shows that the vast majority of C. difficile cases in hospital are isolated cases and have not been spread from other known cases of active infection.
The findings are published in the journal Plos Medicine on Tuesday, 7th February.
C. difficile infection (CDI) is a serious illness which can produce toxins in the colon causing severe diarrhoea and, in the most serious cases, death. Although it has become a significant medical and resource problem in hospitals, nursing and residential homes and in the community, the number of cases has been reducing over recent years. This may be due in part to the success of infection control techniques but it is still unclear where the source of most current CDI cases is.
To find out more about the behaviour of this bug and reduce the risk of infection even further, researchers in Oxford and Leeds have carried out the largest ever study of its kind to investigate how often cases occurring in hospital can be linked to other known cases.
This new, NIHR Biomedical Research Centre Oxford funded, study has found that the vast majority of CDI cases in hospitals are isolated episodes not linked to other known cases. Researchers used forensic DNA techniques to analyse samples across Oxfordshire over a two and a half year period and discovered that no more than 25% of cases were passed on in this way.
During the analysis of thousands of sample, bugs were “fingerprinted” using only a small portion of C. difficile DNA.
Health Secretary Andrew Lansley said: “We have a zero-tolerance approach to avoidable healthcare associated infections.
“Earlier this year we set new ambitions for the NHS to build on progress made last year. If delivered there would be a further 18% reduction in C. difficile infections by April 2013.
“This research indicates that good practice in some parts of the NHS may be helping to prevent infection spreading between patients and this is one reason why the level of C. difficile infections has reduced markedly.
“We know there is still more to do and this study adds to the evidence base and will help healthcare providers identify where cases are originating so that other measures to further reduce infections can be introduced.”
Tim Peto, Professor of Medicine, Nuffield Department of Medicine, University of Oxford, and Consultant in Infectious Diseases said: “We studied 1300 cases of CDI from patients in hospitals, the community and other healthcare settings and found that the vast majority of cases of C. difficile we analysed were unlinked. This means that most of the cases we diagnose are not passed from other known cases of CDI.”
“It is likely that the robust infection control measures taken in hospitals to safeguard against cross infection of CDI have already had a huge impact and that these should continue. What we need to do now though is take this understanding of the pattern of outbreaks to do more research and find out how we can reduce the number of C. difficile outbreaks even further.”
Professor Mark Wilcox, Consultant/Clinical Director of Microbiology/Pathology (Leeds Teaching Hospitals NHS Trust), Professor of Medical Microbiology (University of Leeds, Leeds Institute of Molecular Medicine), Lead on C. difficile infection in England (Health Protection Agency) commented: “We need to find out whether these findings hold true in other hospitals. As we know that some people can carry the C. difficile bug in their gut without becoming sick with it and without having diarrhoea, we now need to investigate if they can be a source of infection for others, or whether there are other ways of acquiring C. difficile and then developing symptoms. By doing this, hospitals will be better placed to reduce the risk of CDI to a minimum.”
Professor Peto added: “This new understanding of C. difficile may lead us to ask whether hospitals could use a different way of measuring CDI in future. We hope it will add to the thinking on how best to target infection control resources to reduce the spread of the bug even further.”
This study was funded by the NIHR Biomedical Research Centre, Oxford, the Medical Research Council and the Wellcome Trust.