ABSTRACT: MRSA is no myth! Methicillin-resistant Staphylococcus aureus (MRSA) is an important nosocomial pathogen in humans and is increasingly implicated in community-associated infections in people. In household pets, MRSA infections are on the rise, possibly because of the increased prevalence of human MRSA in the community. Clinical MRSA infections in some animals can be life-threatening and difficult to treat. However, other individuals may develop mild disease or only become colonised.

Veterinary nurses should be aware – and continue to make themselves aware – of the issues regarding MRSA and should develop an understanding of appropriate disease surveillance, diagnostic testing and infection control in order to help prevent and manage MRSA in the practice environment.

MRSA strains were first seen in the 1960s, but new MRSA strains (Figure 1) appeared in the 1980s, which caused outbreaks of infection in hospitals throughout the world, including the UK. Further new MRSA strains also emerged during the 1990s. MRSA is no more infectious than other forms of Staphylococcus aureus, as the infection process is almost identical to other staphylococcal infections; but it is more difficult to treat because most of our routine antibiotics simply do not work against it.

Figure 1: Electronmicrograph of MRSA

How did resistance come about?

Whenever bacteria encounter an antibiotic (such as methicillin) some of the organisms may be able to survive its effects because they have the ability to mutate. The surviving ‘methicillin- resistant’ bacteria can then multiply, producing bacteria with potentially even better resistance. The chances of MRSA bacteria developing resistance have been increased by:

   people not finishing the full course of antibiotics, which allows bacteria with some resistance to survive and multiply

   overuse of antibiotics, meaning that bacteria in general encounter – and potentially survive – a wide range of antibiotics.

Is MRSA a risk to nurses and clients?

Not under most circumstances. Colonisation is not uncommon and is of little significance in healthy humans. Adherence to routine hygienic precautions, particularly hand washing, will prevent colonisation in most circumstances. However, it is important for practices to implement an infectious disease control policy; and to monitor and control not only MRSA, but other potential problems (Figure 2).

Figure 2: Proper hand washing is particularly effective in controlling infection

Your practice may already have Standard Operating Procedures for infectious agents such as Pseudomonas spp. and Salmonella spp., and these can easily be adapted for MRSA.

Any infectious disease control policy should include:

   a means of identification for MRSA cases

   measures to be taken in managing MRSA or suspected MRSA patients (you can refer to your current barrier nursing SOP, and any SOP for managing Pseudomonas and Salmonella infections for guidance)

   a routine screening policy, which must address areas to be swabbed and at what intervals. Are all staff to be included in the screening process?

   consideration of the personal protective equipment to be used in the management of these cases?

   who will nurse these cases and where in the practice will they be isolated?

   a means of preventing the spread of MRSA and other infectious organisms.

Included in this policy must be clear guidelines as to the disinfectant agents that will be used to clean items and areas listed in Table 1. As well as being aware of the correct agents to use, nurses must consider any Health and Safety implications in using these disinfectants at the relevant dilutions.

Staff who are nursing current – or suspected MRSA cases – should not be involved in nursing other patients and should avoid theatre, dental and other surgical work, where possible. At the very least, they should be advised not to nurse any immuno-compromised animals.

In humans, MRSA is most commonly spread via hands and can linger for a

frighteningly long time, particularly in hard- to-wash areas such as under rings where it can reportedly live for up to two months. Naturally, this provides a prolonged opportunity for it to be passed on through normal daily activities, such as bodily contact and even typing – MRSA can last for six weeks on a computer keyboard!

According to the Royal College of Nursing, effective hand washing and drying is widely acknowledged to be the single most important activity for reducing the spread of infection.

Should SOP include taking of routine swabs?

Yes. This is an important part of an infectious disease control policy. The extent and frequency of sampling depends on the individual practice and circumstances, but routine monitoring should be undertaken every one to three months. Even if your practice has never had a case of MRSA, it does not mean that it is not worthwhile taking routine swabs from, for example, the theatre, prep room and kennels to check for any form of environmental bacterial contamination (Table 2).

Surely it is better to know you may have an environmental contaminant before patients become ill? You may feel that it is excessive to swab all these areas every few months and instead may prefer to opt for taking swabs from different areas each month, or swabbing just a few areas every few months. The individual practice must decide what and when to swab and ensure that it is being done in accordance with the policy.

What animals are more at risk?

Those patients with the highest risk of succumbing to MRSA infection are:

   open and closed wounds and skin infections

   surgery or injury sites where a surgical drain or sutures are in place

   insertion sites of intravenous catheters, urinary catheters and feeding tubes

   surgery that involves the use of any form of implant

   immunocompromisation (including geriatrics and neonates).

   long periods of hospitalisation

   widespread skin and/or mucosal defects.

Other risk factors include patients:

   from known MRSA positive households or that belong to healthcare workers

   with non-healing wounds

   with non-antibiotic responsive infections where previous cytology and/or culture indicates that staphylococci are involved.

It is important for vets and nurses at postoperative checks to wear disposable gloves to examine a surgical wound, injury or drain or at the very least to wash their hands with an antibacterial wash before and after touching the patient. Sadly, as most nurses know, routine hand washing in chlorohexidine-based washes dries the skin. There are now several companies offering alcohol-based hand gels, active against MRSA and available in small enough containers to be carried around in a pocket and used easily between patients and without the need for water!

Should staff be swabbed routinely?

This is a controversial area. The issues of consent, confidentiality and stigmatisation must be carefully addressed. Screening in your practice should be seen as an epidemiological survey to identify areas of weakness in infectious disease control and not as a ‘witch hunt’.

Screening of staff is not, and never will be, a substitute for rigorous infection control measures that are followed by all practice staff. Bear in mind that routine screening can also miss transiently contaminated staff, who may still act as a source of infection if they fail to observe adequate hygienic precautions (Figure 3).

Figure 3: Standard buccal swab for MRSA


Can MRSA pass from humans to animals and vice versa?

In essence, the British Small Animal Veterinary Association says ‘yes’; but the risk is still, at present, thought to be low. Staphylococci are usually adapted to their preferred hosts. S. aureus is mostly isolated from humans and horses (although these appear to be different strains), whereas dogs are predominantly colonised by S. intermedius, and cats by S. intermedius and S. felis. Staphylococci can, however, opportunistically cross species barriers under some circumstances.

How common is MRSA?

The British Veterinary Association estimates that between 10 and 20 per cent of pets are found to carry the bug each year, but has warned the number is currently increasing. The Department of Environment, Food and Rural Affairs (DEFRA), has set up a committee to look at MRSA in pets and livestock.

MRSA is no myth! Methicillin-resistant Staphylococcus aureus (MRSA) is an important nosocomial pathogen in humans and is increasingly implicated in community-associated infections in people??

How long do staphylococci and MRSA survive on surfaces?

As with other pathogens, staphylococci and MRSA can survive on some surfaces for hours, days or even months, but it all depends on factors such as temperature, humidity, the number of pathogens present, and the type of surface – porous like a sponge or non-porous like plastic?

It also depends on whether these surfaces have nutrients to allow the organism to survive longer. When surfaces aren’t cleaned and conditions are good for bacterial growth, they are more likely to survive for longer periods. It is important that practices keep equipment stored away and surfaces clean and tidy (Figures 4 & 5).

Figures 4 & 5: Keep equipment stored away and surfaces  clean and tidy


The idea that household pets can have MRSA is not new. As early as 1959, S. aureus was isolated from the nasal passages of cats and dogs, and it was suggested that they could be carriers for zoonotic infections to humans (Mann 1959). The frequency of transmission between humans and animals is still considered to be very low, but MRSA is here to stay and we must be vigilant in our practices and do our utmost to minimise the infection and colonisation risks, especially as our next threat may be just around the corner in the form of vancomycin-resistant Staphylococcus aureus (VRSA).

With the increase of staphylococcal resistance to methicillin, vancomycin (or teicoplanin) is often a treatment of choice in infections with MRSA. VRSA was first seen in Japan in 1996 and since has been isolated in hospitals in the UK, France, Asia, Brazil and the US. Let’s hope this ‘superbug’ will not be troubling us in veterinary practice any time soon.


Tracy Mayne


Tracy has been a trustee for the RCVS Trust since 2004. The Trust provides all RVNs with free library membership and education grants. She started her working life in a large mixed practice in Cornwall and qualified from Bicton College as a VN in 1994.

After leaving Cornwall, she spent a few years working in London as a company administrator. Tracy returned to practice as a practice manager for a large veterinary group in London, and in 2004 joined the Vets4Pets Support Team. In 2007, she opened Redditch Vets4Pets as the VN partner.

Useful resources

   BBC News (2005) Experts examine MRSA pets 'link', 1 5.08.05.

   BSAVA Website (2005) MRSA FAQs

   Revised MRSA infection control guidelines for hospitals

   Report of a Combined Working Party of the British Society for Antimicrobial Chemotherapy, the Hospital Infection Society and the Infection Control Nurses Association, prepared by G. Duckworth, B. Cookson, H. Humphreys and R. Heathcock.

   Royal College of Nursing. MRSA Guidance for nursing staff.

   BVA. A Policy Brief on MRSA.

   Wikipedia. Vancomycin-resistant Staphylococcus aureus


Veterinary Nursing Journal • VOL 25 • No9 • September 2010 •