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  • Meticillin-resistant Staphylococcus aureus (MRSA) is only one of a number of bacteria that can be resistant to lots of different antibiotics.
  • Pseudomonas aeruginosa is a relatively common finding in long-standing ear disease and some wounds. It does not survive well in air and so is unlikely to spread between individuals.
  • Methicillin-Resistant Staphylococcus pseudintermedius (MRSP) and Methicillin-Resistant Staphylococcus intermedius (MRSI) are probably best thought of as the “animal equivalents” of MRSA – there is little published information on these at present, but it is reasonable to assume that the same basic hygiene precautions as for MRSA will adequately control MRSP and MRSI.
  • Extended Spectrum Beta-Lactamase producing Escherichia coli (ESBL-E. coli) have not been reported in dogs and cats but are a difficult multiple-antibiotic resistant bacteria type recently identified in cattle, sheep and horses. Studies are ongoing to find out how common they are. They can cause urinary infections in humans but have not been reported in food poisoning.
  • In all cases of multi-resistant bacteria – as for ANY bacterium – good hygiene is the best way to prevent problems!

Pseudomonas aeruginosa

Pseudomonas aeruginosa is a common bacterium that is able to colonize many natural and manmade environments. It is commonly found in soil and water but can also be found on animal surfaces. It is known as an opportunistic pathogen which can be particularly dangerous to individuals with weakened immune systems. It can infect most tissues if compromised but is often the cause of ear infections in pets.

Often found in the ears that have been inflamed, infected and unhappy for some time. It may also turn up in deep wounds. As it does not survive well in air, opening wounds up and using special dressings can be an extremely good way of managing it. Its inability to survive in air also means that it is unlikely to spread between individuals or between pets and owners. This bacterium is more likely to be resistant to various commonly used antibiotics. Typically it is the more expensive antibiotics that are effective, thus it can be a costly infection to treat. Culture and Sensitivity tests should establish which antibiotics can be used to treat the infection.

Methicillin-Resistant Staphylococcus pseudintermedius (MRSP) and Methicillin-Resistant Staphylococcus intermedius (MRSI)

MRSP and MRSI are probably best thought of as the “animal versions” of MRSA. Just as a small number of humans carry MRSA either alongside or instead of “normal” S. aureus, a small number (about 5% of dogs and 1% of cats) carry MRSP either alongside or instead of “normal” S. pseudintermedius. MRSA can transmit from people to their pets without ever causing a problem; and around 4% of pet owners may have picked up MRSP from their pet without ever having a problem. Actual infection with MRSP (where the bacteria causes a problem) is exceptionally rare in people.

MRSP and MRSI, like MRSA, cause problems when they get into places they shouldn’t be – most commonly, skin wounds and soft-tissue injuries – where they can then cause infection. Signs of infection are as discussed for MRSA elsewhere on this site. Because they are resistant to many antibiotics, they can be difficult infections to clear. However, again, like MRSA, if they are identified by Culture and Sensitivity and dealt with appropriately, they can be managed extremely successfully. And like MRSA, good hygiene is the best way of minimising problems with MRSP and MRSI! Learn about hand hygiene

Extended Spectrum Beta-Lactamase producing Escherichia coli (ESBL-E. coli)

Escherichia coli can be present in small amounts in the gastrointestinal tract (gut) of many animal species. It can live without causing harm to the host; however certain strains are capable of causing severe illness. E.coli commonly causes urinary tract infections but can also be responsible for gastroenteritis and in rare cases septicaemia. Faecal-oral transmission is normally the route through which disease occurs.

In recent years strains have emerged that are found to be resistant to antibiotics. These are called Extended Spectrum Beta-Lactamase producing Escherichia coli. Certain antibiotics have what is called a beta lactem ring. Beta Lactamase which is produced by these strains of E.coli is an enzyme which breaks down this ring, thus rendering the antibiotic ineffective. This means therefore that ESBL strains can be difficult to treat.

Escherichia coli is a normal bacteria found in the guts of many animals. Recently, a variant of it which resists the action of many types of antibiotics such as penicillins has been found. Penicillin’s (and some other antibiotics) have a chemical structure called a “Beta Lactam ring” in them; ESBL-E. Coli have learned to resist any antibiotic with such a structure. This means that it is resistant to a wide variety of antibiotics.

ESBL-E. coli have been identified in humans. E. coli are a frequent cause of urinary tract infections in humans, if they manage to get from their normal place in the gut to the urinary tract, probably by getting to the perineum then climbing up the urethra. ESBL-E. coli has been known to cause similar problems; the bacteria probably live normally in human guts then cause problems in the same way as normal E. coli, but with the added difficulty of their antibiotic resistance.

To date, ESBL-E. coli has been identified in cattle, horses and sheep in the UK, but not dogs and cats. Studies to find out more about it and how common it is – particularly in normal animals – are underway.

However, just like any E. coli, ESBL-E. coli will be dealt with by good hygiene. Routine hygiene should be adequate to deal with any risks; ESBL-E. coli have NOT been associated with food poisoning to date.

Staphylococcus aureus

is a common bacterium. It can be present on the skin of humans and animals without causing problems. MRSA is a strain which has developed since the introduction of antibiotics, having become resistant to them. Initially it was resistant to Methicillin but it was then discovered it was particular to Beta Lactem antibiotics as a whole. Nowadays S.aureus has developed resistant to various commonly used antibiotics and can even be resistant to Vancomycin, which has often been thought of as a last resort. Although MRSA is not any more virulent than other bacteria, the fact that it is resistant makes it difficult to treat, meaning it is a danger

Clostridium difficile (‘C. diff’) is another bacterium that may show multiple-antibiotic resistance. Again, however, it requires the patient to have been compromised in some other way before it can cause a problem. In fact, it is normally unable to live in the human gut because the commensal bacteria out-compete it for resources. It causes a problem when the gut commensals are killed – ironically, the commensals are normally killed by antibiotics. It causes severe diarrhoea (‘Antibiotic Associated Diarrhoea’ or ‘AAD’). While it is frequently found in hospitalised humans, it has not yet been reported as a major problem in animals.

Pseudomonas aeruginosa (pronounced “syoo-doe-moan-ass”) is a bacterium that tends to affect particularly nasty wounds and dogs’ ears. Unlike MRSA and MRSI, it cannot live in large numbers on normal skin – it is killed by oxygen and prefers stagnant water. However, in serious infections with large amounts of tissue destruction, it can over-grow and cause serious infections. It is particularly common in long-term ear infections in dogs, where the ear has been treated repeatedly with different antibiotic drops.

Research shows that antimicrobial resistance is increasing, and that transmission of resistant E.coli regularly occurs between animal and human.

Multidrug resistance is found to be common amongst faecal E.coli in dogs, however further research is required to fully understand the implications of this. It is important that risk factors are established in order to minimize the occurrence of transmission.

Did you know...

Those who work in health settings, including vets and veterinary practice staff, may have a higher risk of carrying MRSA than the general population.

All about infections



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Infections can generally be treated successfully with a single course of antibiotics, which may come in the form of creams or ointments, injections, or tablets, and many infections will even [&hellip

How we have Helped

Jill Moss has helped all of us pet lovers in so many ways, regarding MRSA. I never even knew about how horrible this can be for our furry children, until [&hellip

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