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The means by which bacteria get into the bladder and cause infection is generally from what is known as “ascending infection”. MRSA/MRSI/MRSP may all live normally around the perineum, the skin between the anus and genitals. Bacteria that are in this area may “climb” up the urethra and into the bladder; this is true of many bacteria that cause cystitis, not just MRSA/MRSI/MRSP. Often the bacterias’ “climb” to the bladder is partially aided by the urethral defence mechanisms not working as well as they do normally (for example in older patients, the immune system may not work as well as normal).
In some cases, when treatment is started, we successfully reduce the number of bacteria infecting the bladder can be knocked down far enough for the patient to start behaving apparently normally. However, if even a tiny number of bacteria remain when treatment is stopped, they may cause a repeat infection some time after treatment stops. For this reason, lengthy antibiotic courses may be needed.
Also, as the MRSA/MRSI/MRSP may live normally on the dog’s skin in the perineal area, this means that even if the MRSA/MRSI/MRSP is cleared from the bladder, it may persist on the skin longer and even return to that area after we thought we had cleared it (much like if we take antibiotics, they may kill “good” bacteria in our intestine, but those bacteria will eventually find their way back). If the bacteria can persist or return to the skin, they may re-invade the bladder. This is similar to humans who may be “prone” to bacterial cystitis and need treatment every so often; it is just unfortunate that the bacteria present are MRSA.
It should be noted that the route of traffic from the bladder is generally one-way; huge amounts of fluid are coming to it through the ureters constantly, and exit through the urethra sporadically. This means that it is effectively being flushed in a one-way direction regularly, and makes it difficult for bacteria to get deeper into the system from the bladder as they would have to either travel through the thick bladder wall or up the ureters against the constant flow of urine. As such, these patients are unlikely to develop lots of other signs besides their cystitis, because the infection doesn’t really get much further. This is again true of most bacterial cystitises, not just MRSA/MRSI/MRSP.
The other means by which bacteria may get into the bladder is via the blood stream, most commonly through the kidneys; however in these cases there are normally signs elsewhere in the animal – they are normally much less well than typical cystitis cases.
In the case of the dog in the nursing home, I suspect that its perineum is colonised; however, as discussed by Annette, decolonisation is an inexact science – we don’t even know if it is possible to do it long term. I suspect it may be just as difficult as trying to rid someone of the bacteria that normally live in their guts.
Should the owners be swabbed? No. The reasons are that:
1) If they are MRSA/MRSI/MRSP carriers, this can be considered entirely normal, in the same way as we all have various other Staphylococcus species all over our bodies – if they aren’t causing a problem, there is no point trying to fix them. They can be considered normal, as opposed to being thought of as an infection.
2) If the bacteria are there normally, we probably couldn’t permanently decolonise either the dog or the owners anyway – at present, chances are that we would do nothing if we found MRSA (as it isn’t causing a problem to the owners) and even if we tried to treat it, we would be trying to decolonise them the same way we would try to remove a normal bug from the human gut – as said before, it’ll just come back most likely, and it wasn’t causing a problem anyway – so what’s the point testing for it if we aren’t doing anything about it? And why drive a potential wedge between a dog and its owners when the owners are actually absolutely fine? It would be horrible for all concerned, not succeed, and also be an attempt to treat a non-existent problem.
3) Finding MRSA on the owners would actually not be sufficient to tell us whether they are actually colonized, or just happen to have had some MRSA splatter onto them from their carrier dog (incidental contamination); therefore, again, in the absence of any clinical signs on them, it would take a lot of repeated samples over a period of time to determine whether the bugs were actually colonising the owners. The information gained by doing so would not change how we treated the owners (for the reasons listed above). Therefore, it would be completely pointless to go through the stress and not-insignificant costs of doing this.
The one precaution I would take is that if they were going to have surgery, or be put on medications that may suppress the immune system, it may be worth checking their MRSA status. This would be done by the doctor if necessary.
Animals that routinely visit healthcare institutions include dogs and cats. They are taken into nursing or residential homes, hospital wards, hospices and long term care facilities. There is no doubt that this can benefit mental wellbeing and recovery from illness. However, there is the possibility that these animals could be carriers of MRSA or other zoonoses, or act as mechanical vectors for transmission between patients and staff. The risk of this compared to the risk from other patients, staff and visitors should, however, be kept in proportion. For example, a small percentage of healthy dogs carry MRSA. This is a similar proportion to healthy people and it is likely that dogs and cats pose no more risk to patients than human visitors and staff.
It is impractical to suggest that animals are bathed or otherwise treated between patients, but steps that could be taken to minimise any risk should include:
Dr Tim Nuttall
Senior Lecturer in Veterinary Dermatology
Head of the Dermatology Service
The University of Liverpool School of Veterinary Science
Animals have a vital role to play in the general well being of people. However, owners of the visiting animals should undertake full and proper hygiene practices, e.g.:
1) The bedding for those animals should be regularly and properly cleaned,
2) The blanket in the back to the car should be treated the same way;
3) Brushes and the likes should be regularly cleaned.
This helps to protect humans from acquiring infections from animals. However, in the specific case of MRSA, it is more likely that humans might pass MRSA to the animals than vice versa – and older / sicker humans in a hospital or care home are more likely to be colonised by MRSA. If the animal is healthy, this remains unlikely to cause infection, but colonisation might be possible..
At the end of the day it is the choice of the pet carer to allow animals to enter premises where MRSA and other bacteria may be present.
The risk factors for MRSA colonisation and subsequent infection are well established in people, but less so in animals. Humans who are most at risk will have had: 1) Exposure to healthcare facilities such as hospitals;
2) Previous surgical procedures;
3) Indwelling devices (e.g. surgical implants such as pins and bone screws);
4) Conditions which reduce the effectiveness of the immune system, such as:
a. underlying medical conditions such as diabetes and human immunodeficiency virus (HIV);
b. old age;
5) Previous MRSA episodes;
6) Prior antimicrobial use, particularly repeated courses of antibiotics.
If your pet has to undergo surgery, avoid courses of antibiotics unless they are necessary. In particular, repeated courses of antibiotics increase the risk of resistant bacteria appearing. There are of course some patients who need repeated or prolonged antibiotic courses – again, talk to your vet if you have concerns.
Finally, be aware that infections that do not seem to be responding to treatment may be a sign of resistant bacteria. Repeated infections can be a sign of the presence of resistant bacteria too; however, repeated infections can also happen for other reasons (e.g. in allergic animals that get recurrent skin infections).
Ask your vet what infection control policy the practice has in place and if you work in health care, or have regular contact with hospitals let your vet know as extra precautions can be taken to protect your pet.
DO NOT PANIC! Basic hygiene reduces the risks of transmitting MRSA to a pet, so practise good hand hygiene and avoid face-to-face contact with a pet as much as is practical, we know this is very difficult to do.
Key points to remember
Keep your pets healthy, with diet and exercise and avoid long unnecessary stays in hospitals as this increases the risk factors for MRSA and other post operative infections. Avoid the overuse of antibiotics in your pet’s lifespan.
IF YOUR PET IS GOING INTO HOSPITAL TALK TO YOUR VET ABOUT THEIR INFECTION CONTROL POLICY (If they are a good vet they will be happy to have this discussion)
MRSA can be successfully treated like any other bacterial infection. If tissue is particularly badly affected, it needs to be removed; wounds may need special dressings; and antibiotics to kill the MRSA must be used. The key is to identify the MRSA as quickly as possible, then treat it.
Make sure your vet takes swabs and cultures and if your vet wants to talk with our veterinary experts this can be arranged. Bella Moss Foundation works closely with vets all over the world, we can get our vets to liaise with yours but we cannot comment on clinical management of cases.
CAN MRSA DISSAPEAR ON ITS OWN?
MRSA can resolve without specific antibiotic therapy. This generally occurs in two ways:
An MRSA infection may resolve if the underlying disease is controlled. This is because the vast majority of infections are secondary to another problem, and, if this is corrected, conditions no longer support the infection. Normal immune and healing processes will then eliminate the infection.
Failure to address the underlying problem will compromise antibiotic treatment leading to persistent and reoccurring infection.
MRSA colonisation (as opposed to infection) is normally lost in the community over 1-6 months. This is because antibiotic resistant organisms can be out-competed and replaced antibiotic sensitive organisms in the absence of selection pressures exerted by antibiotics and away from veterinary and other environments with a higher risk or resistant bacteria.
Strict isolation of infected pets is probably excessive.
General infection control practices (e.g. hand washing after contact with the animal, avoiding contact with the infected site, limiting contact overall) are probably adequate. If you have members of your household with weakened immune systems – including infants or elderly individuals – and have concerns talk to your health practitioners. If need be, let us liaise with them and our experts to get you further advice.
Only infection compromises health and well-being and generally therefore only infected cases either have samples taken from them or are given treatment. In humans undergoing surgery, samples are taken to detect MRSA before surgery – colonized individuals may be treated to minimize the chances of MRSA getting into the surgical wound from the skin and causing infection later (“decolonization”).
As MRSA colonization is much less common in dogs, this sort of treatment has not been recommended widely. Decolonization of a pet is perhaps only needed when its owner needs to be decolonized; as MRSA may spread from owner to pet and back, both might need to be treated – the doctor and vet will need to work together for this. However, decolonization of pets is rarely indicated, partly because there is no evidence how to do it, or if it’s even possible.
Decolonization of MRSA-colonized dogs is not currently recommended in most cases – simply maintaining good hygiene to prevent MRSA problems works best to reduce infections.
Is when a bacteria jumps onto an object or individual, but is then quickly removed – so it is there only for a brief period of time. So, if a dog comes into contact with an MRSA-infected individual, he may pick up some MRSA. If we take samples from the dog soon after this transmission, we’ll find MRSA. However, a few days later we may find that on re-checking the dog, the MRSA has gone. The dog was a “carrier” under these circumstances.
Colonized humans or animals have MRSA living on them without showing signs of disease or illness. The MRSA is one of their commensal bacteria and lives normally on them, frequently around the nose, throat, armpits, bowel, groin and hands. Some individuals are colonized for short periods of time, while others can be colonized for longer periods of time. In general, short-term colonization is typical in animals. Lifelong colonization can occur in people, but there is no evidence that this is an issue in pets.
Confusingly, some people will use the word “carrier” to refer to animals or people who are actually “persistently colonized” (i.e. have MRSA on them constantly, although the bacteria is causing them no illness). The two terms are therefore sometimes used interchangeably, although they really should mean different things.
Most humans are colonized with S. aureus; about 30% are colonized with MRSA.(the 30% number is the percentage of people colonized with S. aureus, not MRSA) Dogs are normally colonized by different types of Staphylococcus to humans. They are less commonly colonized by “ordinary” S. aureus, and MRSA is even rarer than “ordinary” S. aureus – so MRSA colonization in dogs is much rarer than in people.
Remember: The only way to identify an individual as colonized is repeated sampling over a period of time. This is not usually necessary as the MRSA is not causing problems.
Jazz has now recovered from MRSA and is doing well
Infection is where the bacteria is overwhelms the body’s defenses and causes illness. For MRSA, this usually involves the skin being broken (allowing MRSA to get from the patient’s skin to deeper tissues where it should not be) or the patient having some form of immune system weakness (so the immune system does not control the MRSA as it normally would). The bacteria can also produce toxins (poisons), which may spread from the infection site. These often affect tissues surrounding the infection site; but if they get into the blood stream (referred to as “toxemia”); they can cause severe illness through the whole body. Finally, if the bacteria themselves get into the main blood stream (“bacteraemia”; if the bacteria not only get into the blood stream but start reproducing there, it is called “septicemia”), they can spread throughout the body.
Bacteraemia, septicemia and toxemia are rarer than simple localized infection, but are much more severe conditions and need extremely prompt and aggressive treatment.
(TPLO surgery, post op infection in a dog)
The vast majority of infections occurring in companion animals occur after bone (orthopaedic) surgery, especially where pins, screws and other materials need to be left inside the body. Infections can also occur in longer-term conditions such as dermatitis and, in particular, non-healing wounds which can have pus dripping from them.
Emma now recovered from MRSA following surgery on her foot
All skin infections look similar. (Click Here) Skin can become red, hot and swollen. Boils or other abnormal signs such as non-healing wounds may be present. Pus is often a sign of infection.
We always worry when a pet becomes lethargic or loses their appetite. You should always report these signs to your vet; however, they do NOT necessarily mean that your pet has an infection.
If you notice skin irritation, redness, other abnormalities of the skin, or a non-healing surgical wound, then report this to your vet. Taking samples to find out whether bacteria are involved (and if so, what antibiotics will kill them) is always a very good idea – and if the patient is a high-risk case, sampling is extremely important. The techniques used are called “cytology” and “culture and sensitivity”. Cytology tells us if there is an infection happening (it’s possible for bacteria to be present but not actually be causing a problem); Culture and sensitivity testing tells us what bacteria are present and which antibiotics are likely to kill them.
These samples allow us to know that we should definitely use an antibiotic, and help us to choose one knowing that it is likely to work. Without doing these tests, we would have to simply make a guess and choose something off the shelf. However, testing is more expensive, and it will take a few days for results to come back; so the vet will normally choose an antibiotic that they think is likely to do the job in the meantime.
DON’T PANIC – inflammation of a surgical wound is common as part of the healing process; and even if infection is present, the vast majority of cases do NOT have MRSA.
BMF case now owner and cat are doing well
If two individuals are healthy, MRSA can spread from one to the other without either noticing – it is in people and animals that have wounds or some form of immune system problem that such transmission is more likely to cause infection. As it lives on the skin, in the airways and in the environment, MRSA can be spread by skin-to-skin contact (e.g. shaking hands; contact sports) or from indirect contact (e.g. sharing exercise equipment; coughs and sneezes). It can be spread from one environment to another by being carried on people or animals (e.g. a person can take a strain of MRSA from their home with them to a hospital).
MRSA may move in this way from:
It is worth noting that MRSA is less commonly found on companion animals than on people – it is much more common for an animal to get MRSA from their owner than the other way around.
Pets may therefore get MRSA from contact with their owners or other humans (such as owners or veterinary staff). As with humans, pets have immune systems and are at highest risk of actual MRSA infection (as opposed to carriage or colonization) when their immune system is compromised or if they have wounds (e.g. surgical incisions).
Hospitals always present a higher risk of infection. This is because they are closed environments (so people come into close contact with each other); there are lots of patients and staff coming in through the doors (who can therefore bring MRSA in); and there are large numbers of ill patients whose immune systems may not be working as well as normal (who can therefore get infections), as well as large numbers of surgical cases with big wounds.
For this reason we must all be particularly careful to practice good hygiene in hospitals!
MRSA can survive for more than twelve months on dry surfaces however it does prefer a warm moist environment like a wound or the nasal passages. A ceramic tile may be a very hostile environment to MRSA, but the grouting in between tiles may be more habitable. MRSA has been found in hospital ward areas that have been allowed to gather dust. It’s survival on surfaces is however dependent on other factors such as humidity of the environment and its transmission to cause problems is opportunistic.
Bacteria that live on our bodies normally are called “commensal bacteria”. Our bodies are protected by a network of extremely sophisticated defenses, the immune system. Commensal bacteria are controlled by the immune system, and are prevented from getting to places in the body where they could cause problems (i.e., infection).
However, if our defenses are broken – for example, through a deep cut in the skin or a surgical wound; or in certain conditions which stop the immune system from working properly – then commensals like S. aureus and MRSA can break away from immune system control, grow uncontrollably and cause infections.
MRSA can therefore cause infections, and because it is often resistant to many of the antibiotics we use, it is more difficult to kill than other bacteria – hence being called a “superbug”.
Infections with MRSA will often look the same as infections with “normal” S. aureus. So, historically, when infection happened, a patient would be treated with antibiotics that would work against normal S. aureus. Because MRSA is resistant to these antibiotics, it would not be affected by the antibiotic; so, the infection would get much worse over time – sometimes resulting in death of the patient. MRSA has been implicated in deaths of up to 5000 human patients a year in the UK (many more internationally). The number of animal deaths it is involved in is unknown.
These days, any suspicious infection in a human hospital will be sampled to check if MRSA is involved. If it is identified early enough, MRSA can be treated successfully – in both humans and animals.
Bacteria live all around us, on our bodies, in our guts, and in our environments. This is entirely normal, and some bacteria help us to function – you may have seen yoghurt advertisements about the “good bacteria” in our guts which help us digest food. S. aureus live on and around us entirely normally.
When an antibiotic is used, some of the bacteria that are exposed to it can “learn” to fight it off. If you take an antibiotic tablet, the antibiotic spreads all over your body – so bacteria all over your body are exposed to it. Therefore, if antibiotics are used a lot, then bacteria get a lot of opportunities to “learn” to resist the antibiotic. It is thought that over-use of antibiotics by doctors and other health-care professionals from the 1950s onwards has allowed many bacteria to become resistant to antibiotics.
Some S. aureus bacteria are particularly good at becoming resistant to many antibiotics – and so when antibiotics were (and are) over-used, they could develop into bugs like MRSA. MRSA lives in the same places as normal S. aureus, and like normal S. aureus, it is usually harmless.
Like other S. aureus bacteria, MRSA lives on skin but particularly likes moist warm areas such as our nostrils and throats. These bacteria can also live in dust in the environment, so can live in debris in hospitals and houses alike. People thought that MRSA could not survive in dry environments for more than a few hours, but there is now evidence of it surviving on dry surfaces for up to a year.
Because MRSA lives on our skins and in dusty environments, good hygiene is absolutely critical to preventing its spread. Secondly, reducing antibiotic use will prevent the development of antibiotic-resistant bacterial strains.
In some regions, increases in MRSA in pets have lead to the use of important drugs such as vancomycin. These drugs are critically important for the treatment of life-threatening MRSA infections in people, and the use of them in animals is quite controversial. Reducing or eliminating use of these drugs in animals is an important public health consideration. A key part of reducing the pressures to use these drugs is reducing the number of infections. The Bella Moss Foundation supports the rational use of antibiotics, but wishes to stress that good hygiene and a reduction in reliance on antibiotics is essential in the war on resistant bacteria.
Until the 1990s, most cases of MRSA in humans were caused by strains found in hospitals. These types were therefore called “Hospital-Associated” MRSA or “Healthcare-Associated” MRSA (HA-MRSA). These types of strains do not seem to spread easily in the community outside of the hospital, but are frequently resistant to large numbers of different antibiotics. They tend to affect older people or people with conditions that compromise their immune systems.
In the late 1990s, strains of MRSA behaving very differently were identified. They were resistant to fewer antibiotics, but could cause disease in people of all ages and did seem to spread in the community – hence being named Community-Associated MRSA (CA-MRSA). In the USA, one strain of CA-MRSA called USA300 has been causing particular problems and is now the commonest cause of skin and soft tissue infections presenting to Emergency Departments.
Presently, HA-MRSA seems to cause most MRSA infections in animals. CA-MRSA has only infrequently been associated with animals to date.
Interestingly, in any country, the types of MRSA found causing colonization or infection in pets are generally the same types found in the local human hospitals! This suggests that somehow the MRSA has come from the hospital to the animal – the primary source of MRSA in pets may be human hospitals.
Approximately one third of people are carrying S. aureus around in their nose at any given time. Most of these do not have MRSA, as the staph they are carrying are methicllin-susceptible. The percentage of healthy people that are carrying MRSA at any given time is lower, with typical reports ranging from <1-5%, depending on the country and whether the person is at increased risk for encountering MRSA (i.e. working in a human hospital or veterinary clinic, working with pigs in areas where MRSA is in livestock, people that are frequently hospitalized or in longterm care…) The vast majority of people that are carrying MRSA never go on to develop an infection, but they are at increased risk of infection in certain situations, like if they require surgery.
In the UK (human) hospitals, most problems are caused by strains of MRSA called EMRSA-15 and EMRSA-16.
In North America, a strain called USA100 is most common in people in hospitals, although a strain called USA300 is common in people in the general population and in some hospitals.
MRSA stands for “Meticillin-Resistant Staphylococcus aureus”. So what does that mean?
Staph aureus bacteria is found on the skin or in the nose of 1 in 3 people. Drug resistant staph – known as MRSA – is generally only found in about 1-2% of the population. But it’s killing more people than AIDS.
(MRSA is a bacterium, not a virus. MRSA is also known as merca infection, golden staph, mursa infection.
Bacteria are tiny organisms which can only be seen under the microscope. In the same way as there are many types of mammal, of which dogs are one variety, there are many types of bacteria. One variety is known as Staphylococcus aureus (also known as Staph. aureus or S. aureus).
The name Staphylococcus aureus simply refers to what the bacteria looks like. When it is grown, it forms golden-coloured colonies (“aureus” means “golden”). Under the microscope, Staph. aureus are round bacteria and group themselves together so that they look like bunches of grapes. “Coccus” (plural: “cocci”) means a round bacterium and “Staphlye” means “a bunch of grapes”!)
Staph. aureus bacteria live harmlessly all around us, and live quite normally on human skin. In the same way as there are different breeds of dog, there are different “breeds” of S. aureus. MRSA stands for “Meticillin-Resistant Staphylococcus Aureus”. Meticillin is an antibiotic, related to penicillin, which kills most staphylococci. Meticillin-Resistant Staphylococcus aureus is a “breed” of Staphylococcus aureus which is not killed by meticillin. It is often also resistant to many other antibiotics which would kill other Staphylococci. While the media have focused on MRSA as if it is a single type of bacteria, there are actually lots of different types (called “strains” or “clones”) of MRSA. There are different types found in different countries.