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Whole-Genome DNA Sequencing Explains Rise in Cystic Fibrosis Patient Infections

Researchers at Papworth Hospital, the University of Cambridge, and the Wellcome Trust Sanger Institute have discovered why a new type of dangerous bacterial infection has become more common among people with cystic fibrosis (CF) around the world. Through their ground-breaking research, the team has developed new measures to protect CF patients. People with CF are prone to serious infection in part because they have sticky mucus that can clog up their lungs. In recent years, doctors have observed a global increase in the number of infections caused by the antibiotic-resistant bacterial species Mycobacterium abscessus (M. abscessus). M. abscessus is distantly related to the bacterium that causes tuberculosis and is usually found in water and soil. Until now, experts had thought it could not be passed from person to person. "There has been worldwide concern about the rising number of M. abscessus infections in people with cystic fibrosis and anxiety that spread from person to person might be responsible," said Dr. Andres Floto, Research Director of the Cystic Fibrosis Unit at Papworth Hospital, Principal Investigator at the Cambridge Institute for Medical Research, University of Cambridge, and lead author of the research published online on March 29, 2013 in The Lancet. "Our work has allowed us to lead the world in changing hospital infection control: we used state-of-the-art DNA sequencing technology to understand how the infection is being spread, which conventional techniques would have missed. Our results will help to protect patients from this serious infection." The team used the latest methods to sequence the genomes of almost 170 isolates of M. abscessus from CF patients collected over a five-year period. By looking at the fine detail of the relationships between the bacterial genomes to produce a “family tree,” the research team could determine where it was likely that infection had passed from one patient to another. They showed that, even with nationally recommended infection control measures in place, M. abscessus can spread between patients. “Whole-genome sequencing gives the highest resolution when determining the similarities and relatedness of each M. abscessus strain, unravelling the origin of the infection in patients," says Dr. Josie Bryant, joint first author from the Wellcome Trust Sanger Institute. “We've used this method to uncover probable transmission events, having important consequences for infection control." "We are increasingly able to use DNA studies to improve patient care," says Professor Julian Parkhill, Head of Pathogen Genomics at the Wellcome Trust Sanger Institute. "By sequencing the complete genomes of bacteria we can accurately describe where they have emerged from and how they pass from person to person. This knowledge means that the clinical teams can develop new health measures to safeguard their patients. Our aim is to develop the best methods to detect and control infection." This new information has led to rapid changes in how people with CF are cared for in the hospital to protect them from this emerging threat. [Press release] [The Lancet abstract]