Superbug spread from hospitals in major cities to regional health-care centres

Hospitals in large cities act as breeding grounds for the superbug MRSA prior to it spreading to smaller hospitals, a study suggests.

Researchers found evidence that shows for the first time how the superbug spreads between different hospitals throughout the country.

The University of Edinburgh study involved looking at the genetic make-up of more than 80 variants of a major clone of MRSA found in hospitals.

Scientists were able to determine the entire genetic code of MRSA using swabs taken from infected patients.

They then identified mutations in the bug which led to their emergence of new MRSA variants and traced their spread around the country.

We found that variants of MRSA circulating in regional hospitals probably originated in large city hospitals. The high levels of patient traffic in large hospitals means they act as a hub for transmission between patients, who may then be transferred or treated in regional hospitals.

The findings suggest that the referral of patients to different hospitals is a major cause of MRSA transmission around the country. This knowledge could help in finding ways  to prevent the spread of infections. MRSA - methicillin-resistant staphylococcus aureus - first started to appear around 50 years ago following the introduction of antibiotics, to which the bacteria has become increasingly resistant.

The paper published in the journal PNAS, also found that the MRSA strain studied evolved from antibiotic-sensitive bacteria that existed more than 100 years ago.

The research funded by the Chief Scientist's Office, Scotland, the MRC and the BBSRC involved collaboration between The Roslin Institute and Wellcome Trust Sanger Institute in the United Kingdom and the Broad Institute and Mississippi State University in the United States.  

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