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Antibiotic over-use triggered 'superbug' epidemic

25 Jan 2017

The epidemic of ‘superbug’ Clostridium difficile (C. difficile) in UK hospitals a decade ago was mainly caused by excessive use of antibiotics, not dirty hospitals, according to a new study.

In the past, over-prescribing of fluoroquinolone antibiotics had allowed drug-resistant C. difficile to thrive in the guts of patients by wiping out other non-resistant types of bacteria and leaving the way clear for the rapid growth of resistant C. difficile. This boosted the number of infections and led to an epidemic in hospitals.

In 2007, the NHS responded by starting a programme of ‘deep-cleaning’ and other infection control measures. But the study shows that dirty hospitals were not the culprit; cases of C. difficile fell only when fluoroquinolone use was restricted and used in a targeted way, as one part of many efforts to control the outbreak.

The researchers analysed data on the numbers of C. difficile infections and the amounts of antibiotics used in hospitals and by GPs in Oxfordshire, Leeds and nationally. Over 4,000 bacterial samples were genetically analysed to look for drug resistance.

Results showed that a more measured use of fluoroquinolones led to around an 80 per cent fall in the number of drug-resistant C. difficile infections across the UK. In Oxfordshire, approximately 67 per cent of C. difficile bacteria samples were resistant in September 2006, compared to around 3 per cent in February 2013.

Despite adopting measures such as better hand-washing and hospital cleaning, the number of cases caused by non-resistant C. difficile stayed the same before and after the outbreak, and the rate of transmission between people in hospitals did not change. Therefore the findings suggest that appropriate use of antibiotics is the best way to control this ‘superbug’.

The study was carried out by scientists at the University of Oxford, University of Leeds and Public Health England and is published today in The Lancet Infectious Diseases. The work was funded by a partnership of funders including the UK Clinical Research Collaboration, of which the MRC is a partner.

Co-author Derrick Crook, Professor of Microbiology at the University of Oxford, remarked: “Our study shows that the C. difficile epidemic was an unintended consequence of intensive use of an antibiotic class, fluoroquinolones, and control was achieved by specifically reducing use of this antibiotic class, because only the C. difficile bacteria that were resistant to fluoroquinolones went away.

These findings are of international importance because other regions such as North America, where fluoroquinolone prescribing remains unrestricted, still suffer from epidemic numbers of C. difficile infections.”

Dr Ghada Zoubiane, MRC Programme Manager for infections, added: “This work is a great example of how collaborations of funders from the NHS, charity and academic sectors can come together to solve pressing public health problems.”

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