Understanding host jumps by Staphylococcus aureus
Bacteria may be able to jump between species with greater ease than was previously thought.
Researchers at The Roslin Institute have found that a type of the MRSA bacteria found in humans originated in cattle at least 40 years ago. They studied the genetic make-up of more than 40 strains of a bacterium – called Staphylococcus aureus – that can build up antibiotic resistance to develop into MRSA. At least two genetic subtypes of the bacterium, which have become endemic in people, have been traced back to cattle. The bug most likely crossed over from cattle to people through direct contact – perhaps through people working with farm animals.
After switching to human hosts, the Staphylococcus aureus bacterium became resistant to the antibiotic methicillin and developed into methicillin-resistant Staphylococcus aureus or MRSA.
In addition, the team have characterised the changes that occur in S. aureus genomes that allow them to adapt to new hosts. They found that a single nucleotide change in the genome is sufficient to enable some isolates to cause disease in rabbits.
- Spoor LE et al. (2013) Livestock origin for a human pandemic clone of community-associated methicillin-resistant Staphylococcus aureus. MBio 4:e00356-13. doi:10.1128/mBio.00356-13.
- Viana D et al. (2015) A single natural nucleotide mutation alters bacterial pathogen host tropism. Nat Genet. 47:361-6. doi:10.1038/ng.3219.
Cattle can be a source of MRSA in people, scientists find. News story 2013.
Bacteria study helps gauge human-animal infection risk. News story 2015.