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Test and treat our dogs’ bacterial skin infections: Time to look after our antibiotics

By Anette Loeffler, Associate Professor in Veterinary Dermatology, RVC Small Animal Referrals, Royal Veterinary College

Over the past year, most of our lives have been dominated by a viral pandemic. However, bacterial infections and in particularly the problems associated with multidrug-resistant bacterial pathogens remain amongst the biggest challenges to human and animal health of our time. Antibiotics are life-saving drugs that are used to treat bacterial infections in humans and other animals, and a wide range of antibiotics are licensed in the UK for the treatment of dogs and cats.

But every time antibiotics are used in a particular patient it can lead to antimicrobial resistance. Antibiotics do not just kill the target bacteria that cause infection, they also affect the ‘good bacteria’ in the gut and on the skin, and treatment will then leave behind resistant bacteria that have managed to develop the ability to evade the effect of antibiotic drugs that were designed to kill them. With their competitor bacteria then decimated, drug-resistant bacteria can continue to grow, and they will then be in a good position to cause infection next time the animal (or human) is due to develop an infection.

In small animal veterinary practice, skin and ear problems in pets are amongst the most common problems, particularly in dogs, and many are complicated by bacterial infection. In fact, bacterial skin infections (pyoderma) in dogs are amongst the top four conditions that lead to antibiotic prescribing in small animal veterinary practice. They are rarely life-threatening but are most often either itchy or painful and can thus substantially compromise our dogs’ well-being or quality of life. The availability, efficacy and safety of a wide range of veterinary licensed antibiotics and antibacterial agents is critical in healing these ‘nuisance’ or sometimes severe deeper skin infections.

However, over the past twenty years, not unexpectedly, some highly drug-resistant skin pathogens have emerged. Such problematic, multidrug-resistant bacteria involved in skin infections of dogs and cats, include meticillin-resistant Staphylococcus aureus (MRSA), more widely known as a human hospital-associated pathogen, and the related, dog-adapted bacterial pathogen MRSP (meticillin-resistant Staphylococcus pseudintermedius). Both MRSA and MRSP can be transmitted directly on contact between people and pets in both directions or via contaminated environments. They can colonise healthy skin without causing signs of disease, but when they get into deeper or damaged tissues, such as wounds or inflamed skin, they can then trigger infection and lead to significant disease.

In order to limit the impact of MRSA and MRSP infections on our pets health and reduce the risk of in-contact humans or animals acquiring such infections from an infected pet, a few steps are critical that may not have been so urgent twenty years ago, when antibiotics could still be expected to work against almost all bacterial infections provided they were used correctly. These steps include:

  1. Early recognition of multidrug-resistant bacteria through more frequent laboratory testing – despite the initial cost of the laboratory charge, identification of the bacterial pathogen will lead to informed treatment selection, likely quicker resolution and thus avoid unnecessary expenses for unsuitable treatment and the cost of spreading multidrug-resistant organisms.
  2. Identification and correction of underlying diseases that led to bacterial infection – to prevent recurrent infections and speed up clinical cure.
  3. Appropriate treatment choices – for skin and ear infections this will more often involve topical treatment options, such as antibacterial shampoos, creams or drops. Although these treatments are more time consuming, require a co-operative patient and typically need to be applied several times a day or week (in contrast to the more convenient once or twice daily tablet option), they will allow targeted treatment of the diseased organ alone and reduce the risk of antimicrobial resistant bacteria being encouraged.
  4. Good hygiene measures at home and in the practice environment, even after infections have been resolved – this is particularly important when multidrug-resistant organisms were identified such as MRSA and MRSP.

At a time of multidrug-resistant bacteria complicating previously easy-to-treat conditions, more diagnostic laboratory testing, the above measures can make a significant impact in limiting the spread of antimicrobial resistance, at least for skin infections where infection is happening right under our hands. Although often less convenient than what was recommended historically, these steps will help to preserve lifesaving antibiotics for future generations and for our pets should they get more serious or deeper infections.

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