A map tracking the spread of a bacterial strain of clostridium difficile

Scientists at the University of Liverpool have identified the origin of an epidemic strain of Clostridium difficile (027) and its mode of spread using tagging genetic signatures in the DNA of bacteria, some of them associated with its increased virulence.

Clostridium difficile is the most common cause of antibiotic-associated diarrhoea and healthcare-related infection in the developed world.  On average, ill patients display symptoms for more than 10 days and a third develop severe disease, including bloody diarrhoea and septicaemia.  Until now, however, the key moments in the infection's evolutionary history have remained unknown.

Scientists at Liverpool, in collaboration with the Wellcome Trust Sanger Institute, Hinxton, and a number of investigators worldwide, have discovered that a more virulent strain of the bacteria originated from two outbreaks in North America in 2003-4, thought to have been driven by widespread prescription of broad spectrum antibiotics.

This particular strain quickly spread throughout Europe, including a notorious outbreak at Stoke Mandeville Hospital.  Using next generation microbial sequencing, evolutionary analysis and epidemiological information, the team identified subtle signatures in the bacteria's genome that allowed them to pinpoint its worldwide spread.

''We know these organisms are resistant to commonly prescribed antibiotics and disinfectants but perhaps more intriguing is the fact that its rapid spread throughout the world has been more about the ease and frequency with which we travel today''

The data suggests that there were at least four routes of entry for this epidemic strain into UK, three of which arrived independently from North America in Exeter, Ayrshire and Birmingham, and another one which arrived in Maidstone from continental Europe.