The vast majority of C. difficile cases in hospital are isolated cases and have not been spread from other patients, researchers in Oxford and Leeds have found.
This counters the widely held belief that most infections are spread in hospital from patient to patient. The researchers, part of University-NHS partnerships in Oxford and Leeds and funded by the National Institute of Health Research, published their results in the journal PLoS Medicine.
Professor Tim Peto of the Nuffield Department of Clinical Medicine at the University of Oxford said: 'We studied 1300 cases of C. difficile infection 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 C. difficile infection.
'It is likely that the robust infection control measures taken in hospitals to safeguard against cross infection of C. difficile 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.'
C. difficile infection can be a serious illness, causing severe diarrhoea and, in the most serious cases, death. Although it has become a significant medical and resource problem in hospitals, nursing 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 the source of cases is most often unknown.
The researchers in Oxford and Leeds investigated how often cases occurring in hospital can be linked to other known cases by analysing a section of C. difficile DNA from thousands of samples taken across Oxfordshire over a 2½ year period.
They discovered that no more than 25% of C. difficile infections were passed on from other known cases.
Professor Mark Wilcox of the Leeds Teaching Hospitals NHS Trust and the Health Protection Agency’s lead on C. difficile infection in England said: '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, who is also a Consultant in Infectious Diseases at the Oxford University Hospitals NHS Trust, 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.'
Health Secretary Andrew Lansley commented: '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.'
The study was funded by the NIHR Biomedical Research Centre, Oxford; the UK Medical Research Council; and the Wellcome Trust.