Authors of the study discovered humans were the likely original host for the bacteria that causes mastitis in cattle and infections in millions of broiler chickens.

Scientists have made a major breakthrough in the fight against the bacteria that causes mastitis in cattle and infections in millions of broiler chickens.
Novel therapeutic targets in the fight against Staphylococcus aureus could be identified within “five years”.
The prediction comes following the publication of a major study that analysed the entire genetic make-up of more than 800 different strains of S aureus. The pathogen is also responsible for antibiotic resistant strains of MRSA – a major cause of hospital-acquired infections for humans.
The study, published in Nature Ecology and Evolution, investigated the evolutionary history of S aureus and how it can jump between species.
The authors found humans were the likely original host for the bacteria. The first strains capable of infecting livestock emerged around the time animals were first domesticated for farming.
A team, led by The University of Edinburgh’s Roslin Institute, said its findings revealed fresh insights into how new disease-causing strains of the bacteria emerge.
Working with colleagues from the Universities of Edinburgh and Cambridge, and the Wellcome Sanger Institute, authors of the paper believe their findings could, ultimately, point the way towards creating alternatives to increasingly resistant antibiotics for treating infection in both humans and animals.
Ross Fitzgerald, group leader at The Roslin Institute and director of Edinburgh Infectious Diseases, said: “This study has been a real collaborative effort between numerous research groups in the UK and beyond. Our findings provide a framework to understand how some bacteria can cause disease in both humans and animals, and could, ultimately, reveal novel therapeutic targets.”
He explained by comparing the genetic code of S aureus isolates from different species, the team had been able to look at the evolutionary relationship of the bacteria to each other.

‘Host jumps’

Prof Fitzgerald said: “What this has shown is S aureus has probably co-evolved with a human host for a long time in evolutionary terms, but it has made a switch into other host species including cows, goats, sheep, chickens and pigs – so it’s jumped from humans into those different host species, and adapted genetically and functionally to colonise, survive and cause disease in that new host species.”