Deadly hospital super-bug started in North America, say DNA detectives
C.difficile sparked a global epidemic in hospitals in the early 2000sBug started as two drug-resistant strains – one in U.S. and one in CanadaFirst strain hit thousands in U.S, South Korea and SwitzerlandSecond strain spread to North America, Europe and Australia
12:04 GMT, 10 December 2012
A deadly bug that has claimed thousands of lives around the world began in North America, a study has found.
Scientists traced the origins of Clostridium difficile (C.diff) to two separate drug-resistant strains that emerged in the US and Canada.
Both produce tough spores that spread easily over long distances – even between continents – and are hard to eradicate.
The strains, FQR1 and FQR2, went on to spark a global epidemic in the early to mid 2000s.
The second drug-resistant strain of C difficile (FQR2), arrived from North America in 2003. This map reveals how scientists believe it then spread around the UK
C.diff is a bacterium that infects the gut, causing diarrhoea, fever and cramps. In some cases, infection can lead to life-threatening complications.
Those most at risk are people in hospital taking broad-spectrum
antibiotics, those with serious underlying conditions and the elderly.
More than 80 per cent of C.
However, at the height of the outbreak in 2006, Nicola Redfern, 32, became the first healthy young person to die from the infection in Britain. The mother from Staffordshire died less than two weeks after having a son after a series of doctors failed to diagnose the superbug, which she picked up in hospital.
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C.diff is a bacterium (see right) that can cause
diarrhoea, fever and cramps. It can lead to life-threatening infections
to vulnerable patients in hospitals. C.diff spores are highly resistant to most cleaning materials, therefore hand washing is very important
Lead researcher Dr Miao He, from the
Wellcome Trust Sanger Institute in Cambridgeshire, said: 'Between 2002
and 2006, we saw highly publicised outbreaks of C. difficile in
hospitals across the UK, USA, Canada and Europe.
used advanced DNA sequencing to determine the evolutionary history of
this epidemic and the subsequent pattern of global spread.
found that this outbreak came from two separate epidemic strains or
lineages of C. difficile, FQR1 and FQR2, both emerging from North
America over a very short period and rapidly spread between hospitals
around the world.'
Nicola Redfern, 32, died from C. difficile in 2006 two weeks after giving birth to her son Zachary
Co-author Professor Brendan Wren, from the London School of Hygiene and Tropical Medicine, said until the early 2000s, the antibiotic fluoroquinoline was an effective treatment for C.diff. But the North American strains both proved resistant to the drug, making it useless.
'We've seen that since these strains acquired resistance to this frontline antibiotic, not only is
it now virtually useless against this organism, but resistance seems to have been a major factor in the continued
evolution and persistence of these strains in hospitals and clinical settings,' said Prof Wren.
The first outbreak strain of C.diff, FQR1, originated in the Pittsburgh area of the U.S in 2001 and quickly spread across the country, before jumping to south Korea and Switzerland.
It was followed by FQR2 which emerged in 2003 from the Montreal area in Canada, and spread rapidly over a much wider area, covering the whole of North America and reaching out to Europe and Australia.
Tracking the spread of C.diff to the UK, the researchers pinpointed separate transmissions from North America to Exeter, Ayrshire and Birmingham. Another transmission event brought the bug from continental Europe to Maidstone in Kent.
These events triggered large scale C.diff outbreaks in many UK hospitals.
'We have exposed the ease and rapidity with which these fluoroquinolone-resistant C. difficile strains have transmitted across the world,' said Dr Trevor Lawley, another member of the Sanger Institute team.
'Our research highlights how the global healthcare system is interconnected and how we all need to work together when an outbreak such as this occurs.
'Our study heralds a new era of forensic microbiology for the transmission tracking of this major global pathogen and will now help us understand at the genetic level how and why this pathogen has become so aggressive and transmissible worldwide.
'This research will act as a database for clinical researchers to track the genomic changes in C. difficile outbreaks.'