Livestock-associated Staphylococcus aureus.

Staphylococcus aureus has long been associated with livestock. Livestock can be carriers of S. aureus, but can also become infected. The best-known infection is bovine mastitis. The discovery of methicillin-resistant S. aureus belonging to sequence type (ST)398 boosted interest in livestock-associated S. aureus. ST398 is pandemic. Whole genome sequencing and other genetic analyses have shown that livestock-associated strains are distinct from human-derived strains. However, there is also an exchange of strains between the reservoirs. Livestock-associated and human-associated strains share virulence factors, but have also distinct virulence factors that appear to be important in host adaptation. Exchange of genes encoding these virulence factors between strains may expand the host range and thereby threaten public health. Vaccination of animals may be a solution to this problem, but new avenues for vaccination need to be explored, because no vaccine is currently available.