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Companion animal practice – MRSP and MRSA

Anette Loeffler describes the challenges in canine pyodermas and multiple drug resistance in this video.
Hello, everybody. I’m going to talk about problems with canine pyoderma or, in particular, MRSP and MRSA. My name is Anette Loeffler. I’m a dermatologist at the Royal Veterinary College here. And the topic of bacterial skin infections is probably something that you’re all very familiar with. In surveys, bacterial skin infections are listed amongst the top three dermatological conditions seen in small animal practice. What is important is that dogs do not get bacterial skin infections for no reason. There is always an underlying cause. And 60% to 90%, as you all know, are due to Staphylococcus pseudintermedius. So Staphylococcus pseudintermedius is our predominant skin pathogen in the dog.
And the reason why we talk about bacterial skin infections here is that they often lead to antimicrobial use. And one survey showed that actually 92% of dogs with pyoderma were prescribed systemic antibiotics– so potentially scope for improvement. And you can see here the most commonly seen conditions are surface pyoderma on the top, a superficial bacterial folliculitis pyoderma type in the middle and then deep pyoderma here on the chin of a dog, but that can be seen in other areas of the body too. Good. What’s the problem then? Well, the problem is that we now have multidrug-resistant Staphylococci in the form of MRSA and MRSP. You are probably quite familiar with MRSA known as the human hospital bug.
It’s also been identified in pets. But the prevalence in dogs, really, or in pets depends on the MRSA levels in human hospitals because it is seen as a spillover from human hospitals. MRSP, on the other hand, or methicillin-resistant Staphylococcus pseudintermedius is a veterinary problem. Its current prevalence in the UK is around 5%, but up to 50% in other countries, such as the US, continental European countries, and Asia. And what is important here is that the methicillin resistance is just a marker for broad beta-lactam resistance. And what this means for us in the clinic is that MRSP isolates are resistant to all beta-lactams.
As you can see here, there is a collection of 12 isolates and with their typical antimicrobial resistance pattern shown. So mostly R’s– it’s a proud collection of R’s. And the only susceptibilities reported in vitro here are to gentamicin, rifampicin, which are not antimicrobials licenced for use in dogs, and fusidic acid, which we’ve only got available to us for topical use– so very limited options for systemic treatment. And an additional layer of complication here is that Staphylococci can be transmitted between pets and people in both directions. So we have to consider that MRSA and MRSP have got a zoonotic potential.
While MRSA is well adapted to humans, MRSP is well adapted to dogs, and, therefore, MRSP needs to be considered a veterinary nosocomial pathogen, and we need to think of practice hygiene and other things, as we’ll see later. Then another problem is that there are no clinical markers for methicillin resistance. In the top row here, you’ve got a surface, a superficial, and a deep pyoderma due to methicillin-susceptible Staphylococci, and in the bottom row you’ve got pyoderma due to methicillin-resistant Staphylococci. And essentially, they look the same. So the only way to tell the difference is if you do culture and susceptibility testing. But we all know that we don’t do culture and susceptibility testing in every case. Why not? Well, it’s expensive.
We have to explain to the owner the extra cost, and there is a time delay. But we should really always submit samples for testing in cases of deep pyoderma when we see rods on cytology, if there is a previous history of MRSA or MRSP, and if there are risk factors for resistance, which are repeated use of antimicrobials because that selects for multidrug resistance, if animals have visited our clinics repeatedly, or when empirical therapy has failed and failed even just once. So at an era where MRSP and MRSA are around, it’s no longer appropriate to just upgrade from one antibiotic to a bigger bullet.
So basically what that means is pyoderma is no longer just a spotty rash that we can treat with antibiotics. We need to spot these MRSPs and MRSAs early through knowing the risk factors, bacterial culture. We need to educate the owners that this is more than a spotty rash that affects the dog, that it could have implications on human health. And the way to avoid the spread of these multidrug-resistant organisms is to avoid unnecessary systemic antimicrobial therapy and good diagnostics before we actually prescribe antimicrobials. So be alert and stay vigilant. Thank you very much.

In this video, Anette Loeffler, associate Professor of vet dermatology at RVC, discusses the challenges of MRSP and MRSA, in the context of canine pyoderma.

Bacterial skin infections in dogs are very common, with an increasing incidence of AMR. Currently 92% of cases of pyoderma are treated with systemic antimicrobials. In this context, AMS is about establishing the underlying causes of these infections and identifying non-antimicrobial treatment options.

In addition, few animal owners appreciate the zoonotic potential of MRSA and MRSP; they can be transmitted between pets and people in both directions. Owner education is required in this area.

Another big challenge is that methicillin resistance cannot be detected on the basis of clinical examination findings alone. Culture and susceptibility testing is paramount.

In the comments section below, discuss with other learners about how antibiotic resistant bacteria are bringing other challenges to veterinary practice. In week 2, Anette Loeffler will describe how these challenges can be addressed. Before you get there, discuss some of your own ideas in the comments section.

Please find a downloadable copy of the PowerPoint slides used in the video in the downloads section below.

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Antimicrobial Stewardship in Veterinary Practice

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