How C diff travels the world11th December 2012
Researchers in the United States say they have identified two strains of the superbug Clostridium difficile that can spread rapidly.
Once they become resistant to antibiotics, the C difficile strains quickly infected hospitals around the world.
The study carried out a forensic analysis of the bacterium's genetic code, and were able to show how it had travelled.
Once the bacteria became resistant to antibiotics, they seemed to cause more severe infections, according to the study published in the journal Nature Genetics.
The bacteria are now believed to account for 14,000 deaths in the US every year, according to statistics from the US Centers for Disease Control and Prevention.
While C difficile has been a problem in hospitals around the world for many years, big outbreaks in Europe, Canada and the US have sparked growing concern.
The researchers could tell how closely related the different strains were, in their samples gathered from hospitals around the world.
Because C difficile mutates rapidly, it is possible to trace it back along the branches of its genetic ancestry, and work out where it came from.
Using 151 samples from infections in 19 countries, researchers were able to map exactly how the resistant strains of the bacterium had spread across the world.
Among the strains they traced was one called FQR1, which ended up in South Korea, via Switzerland, having started in the US.
A second strain, FQR2, emerged in Canada, crossed the border into the US, before arriving in Europe and Australia. Researchers were able to track four separate occasions on which it entered the UK.
According to Trevor Lawley, of the Wellcome Trust Sanger Institute, there are valuable lessons to be drawn from the study.
Researchers now know the mutation of strains is driven by antibiotic resistance, and goes on far more than previously thought.
It has also become clear just how fast the bug can travel, arriving in the UK from Canada in a matter of months, Lawley said.
At the London School of Hygiene and Tropical Medicine, Brendan Wren has spent more than two decades studying C difficile, and said it became more severe and more easily transmitted once it had acquired resistance to fluoroquinolone.
That antibiotic is now virtually useless against the bug, and resistance appears to have driven its evolutionary process, Wren said.
The research was aided by the fact that the cost of sequencing a bacterium genome have fallen sharply in recent years, and the task now takes less than a day and costs as little as £40.
Researchers hope they will now be able to monitor the spread of diseases while outbreaks are happening, using similar techniques.
They have also gained a better understanding of how to tackle C difficile infections and outbreaks.
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Title: How C diff travels the world
Author: Luisetta Mudie
Article Id: 23346
Date Added: 11th Dec 2012