Dog - MRSA - Methicillin Resistant Staphylococcus aureus

MRSA in veterinary practice was highlighted in 2004 when several cases were confirmed.  For some years prior to this the MRSA 'super bug' had been recognised as a huge problem in many human hospitals.

Staphylococcal bacteria of various species are commonly found as commensals (cause no harm), on the skin surface and natural orifices of both us and our pets.  Some of these, particularly Staphylococcus aureus and Staphylococcus intermedius can, in certain circumstances become pathogenic, (disease producers).  For example acute moist dermatitis (wet eczema) is not uncommon particularly in summer time with dogs suffering from anal gland impaction, fleas, or ear problems.  The initial cause results in irritation and the dog responds by scratching and rubbing.  This damage to the skin results in the commensal Staphylococcae spp. multiplying and causing skin infection so the wet eczema gets worse due to Staphylococcal superficial pyoderma (skin infection).  The Staphylococcae spp. are now pathogenic (disease producing).

The majority of the resulting cases of acute moist dermatitis clear up very rapidly with the use of appropriate antibiotics to which the Staphylococcae spp. are sensitive.  If the Staphylococcal organism is resistant to methicillin, (a synthetic penicillin) it is likely to be resistant to many other commonly used antibiotics.  Then the dermatitis does not respond to treatment and the infection is classed as MRSA.  The MRSA organism, now highly pathogenic, continues to multiply and, via the bloodstream, is capable of affecting other organs in the body, ultimately causing the death of the patient usually due to septicaemia.

Medical and veterinary research over the last few years has shown that these antibiotic resistant Staphylococcae can be passed to and from people and companion animals.  Not only people but dogs, cats and horses are involved.

In the normal healthy individual irrespective whether cat or dog, these MRSA organisms retain their commensal status.  They cause no harm.  If on the other hand the host becomes stressed or debilitated in any way the Staphylococcae spp. can multiply rapidly and become pathogenic.  If the organism involved happens to be resistant to methicillin and other antibiotics, instead of control being a simple matter of antibiotic administration it becomes more serious.  A suitable antimicrobial drug has to be found and this can only be by laboratory testing against the particular organism.  In some cases this creates sufficient delay, and the superbug wins, septicaemia prevails and the patient dies of MRSA.

What can be done?

Fortunately MRSA is well recognised in small animal veterinary practice today and standard hygiene procedures are in place.  Since a debilitated canine patient can easily acquire the Staphylococcus from an attendant, strict hygiene is exercised.  Hand washing, the wearing of gloves and protective clothing is now commonplace, not only in theatres but throughout examination, treatment and ward areas.  MRSA is susceptible to many common disinfectants and these, used regularly, ensure that the spread by environmental contamination is kept to a minimum.

Please consult us with any concerns and we will do our best to help.