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Bacteria study helps gauge human-animal infection risk

Bacteria may be able to jump between species with greater ease than was previously thought, a study suggests.

February 2015

Researchers have found that a single genetic mutation in a strain of bacteria that infects humans enables it to also infect rabbits.

The discovery has major implications for how we assess the risks associated with bacterial diseases that can pass between people and animals.

Domestication of animals, industrialisation of agriculture and  globalisation have provided new opportunities for the transmission of  bacteria between humans and animals. This latest research has important  public and veterinary health implications which will require a  re-examination of the future threat posed by bacterial host-switching  events.

Professor Ross FitzgeraldThe Roslin Institute, University of Edinburgh

Rabbit disease

Scientists at the Universities of Glasgow and Edinburgh studied a strain of bacteria called Staphylococcus aureus ST121, which is responsible for widespread epidemics in the global rabbit farming industry.

The team looked at the genetic make-up of ST121 to work out where the strain originated. They also tracked how changes in its genetic code enabled it to infect rabbits.

Host jump

They concluded that ST121 most likely evolved as the result of a host jump from humans to rabbits around 40 years ago. A  genetic mutation at a single site in the bacterial DNA code was  sufficient to convert a human strain into one that could infect rabbits.

The discovery transforms our understanding of the minimal genetic changes that are required for bacteria to infect different species.

Our results represent a paradigm shift in understanding of the minimal adaptations required for a bacterium to overcome species barriers and establish in new host populations. 

Professor Jose PenadesInstitute of Infection, Immunity and Inflammation, University of Glasgow

Skin infections

ST121 is found in the respiratory tract and on the skin of some people. While it is usually harmless, the bacteria can cause a variety of conditions from minor skin infections to meningitis and sepsis. In rabbits, the bacteria can cause serious skin infections.