MRSP: Are You Ready?

Written by: Dr. Andrew Carter BVSc DVD

What is MRSP

Staphylococcus pseudintermedius is the normal staphylococcus found on dogs and cats. In normal patients it does not cause disease, however, if the body’s immune response is compromised such as by disease, surgery or medication, then infection can occur. Methicillin resistance in staphylococcus pseudintermedius was first reported in 2007 and showed up in Europe, the U.S.A. and Japan shortly afterwards. Methicillin resistance is an indicator of likely resistance to all β-lactam antibiotics (cephalosporin and penicillin).

Why We Should Care

Until recently, we have been able to routinely treat bacterial infections in dogs and cats with an empirical selection of antibiotics. Failures to respond were generally limited to those where an insufficient dose, insufficient duration or concurrent glucocorticoids were used.  As MRSP becomes more common, we are beginning to see cases where routine antibacterial treatment is ineffective.  In some cases, we find that no oral antibiotics are effective. In some locations overseas, the isolation rates of MRSP are up to 70%.

What is the situation in Australia?

While not yet widespread in Australia, colleagues at Melbourne Veterinary Specialist Centre (MVSC) in Melbourne have diagnosed over 50 cases of MRSP over the last year. Around Australia veterinary dermatologists are progressively seeing more cases of MRSP.  So far, I have identified 3 cases myself this year.

What Should I Do About It?

In Australia we have the opportunity to slow the spread of MRSP at a relatively early stage but this will require all Australian veterinarians and specialists to take action.  We want to delay and decrease the spread of MRSP between pets, particularly those that are immunocompromised or have been treated with antibiotics.
At AVSARC, we have instituted protocols to reduce the spread between patients. With the completion of our building works late this year, we will be asking patients with MRSP and patients with a history of recurrent infections to use a separate entrance and consulting rooms away from those used by surgery and medicine patients.

We recommend that all practices review their own infection control protocols. In addition, use of antibiotics should be reviewed.  When infection is suspected, antibiotics should be chosen based on known or suspected organisms. The antibiotic dose and duration should be chosen to minimise mutation rates and treatment should continue for an adequate length of time to ensure infections resolve completely.  For skin diseases, these doses are often significantly higher than the label doses. Adding topical treatments will generally improve speed and efficacy of oral treatments.  We should avoid concurrent use of glucocorticoids and antibacterial therapy where possible.

How can we stop spread of MRSP?

We cannot tell which animals are carrying MRSP without performing bacterial cultures. Therefore, routine precautions should be used at all times. The most important and simplest measure is to wash hands using soap and water or use alcohol-based hand sanitisers before and after handling each patient.  Hard surfaces can be treated with a range of antiseptics. Most require 10 minutes contact time to be effective. The exception is 70-90% alcohol which rapidly kills MRSP and is more practical to use between patients.

When we have a known case of MRSP we have a much stricter protocol. This involves keeping infected patients out of the shared waiting room, using disposable protective clothing, using consulting rooms that are not used for other patients (until they have been fully cleaned and disinfected).  We also ask owners to use hand sanitiser before approaching reception areas.

We will consider all other pets in an infected patient’s household to be infected and because of this, they should also be subject to the same protocols. Once the patient’s infection has resolved they will still be considered a carrier until proven otherwise.

If you are referring a patient with suspected or confirmed antibiotic resistance, please let our reception staff know when you make an appointment.

It is up to us all

While we will never be able to prevent antibiotic resistance, by careful planning and preparation we can minimise and delay the development of more widespread antibiotic resistance.