In human medicine, diseases caused by methicillin-resistant Staphylococcus aureus (MRSA) are known and feared as so-called “nosocomial infections”. These are infections with pathogens that have developed resistance to common antibiotics. The pathogens can enter the environment through hospital visitors, personnel, equipment etc. As most of these infections in humans are zoonoses, pathogens can also be transmitted to animals as well as vice versa, because of the close contact between humans and animals. This probably also leads to an increase in MRSA cases in veterinary medicine.
MRSA is often detected in farm animals. In 2016, only about every fourth pig in Germany was MRSA-free. Approximately every fourth horse was an MRSA carrier (zoonoses monitoring 2019). In agricultural livestock, MRSA of a certain line are predominant, so that the term livestock-associated or laMRSA is used. laMRSA mostly belong to the clonality CC398 and were responsible for 8% of MRSA cases in humans in 2017 and for 5% in 2018. In regions with high livestock density, laMRSA cause increasing numbers of human MRSA cases. People with close animal contact, including veterinarians, are particularly at risk.
In small animals, we detect MRSP, methicillin-resistant Staphylococcus pseudintermedius, far more frequently than MRSA. According to our own research, about 8% of all isolates of Staphylococcus pseudintermedius (formerly Staphylococcus intermedius in dogs) are already afflicted with a multidrug-resistance gene.