Optimal antimicrobial duration

Welcome to the Australian Prescriber. Australian Prescriber, independent, peer-reviewed and free.

I’m Dhineli Perera, your host for this episode and it's a pleasure to be speaking to Dr Kathryn Daveson. Kathryn writes about optimal antimicrobial prescribing in general practice. Kathryn welcome to the program.

Thanks for having me.

Kathryn can you start by telling us what the consequences are of poor antimicrobial prescribing? Why do we make such a fuss about it?

Well you know antimicrobial prescribing is actually pretty difficult and I'd like to give kudos to anyone prescribing antibiotics because I find it hard and that's basically all I do every day, although many times I don't prescribe antibiotics, but it is hard when you're faced with a patient in front of you. There are a number of consequences which I think as practitioners we probably underplay a little bit. The first one that I worry about clinically is when I don't pick the right drug. So, when I'm not following guidelines, we have a lot of literature now that shows that we actually choose much worse in terms of drug bug coverage. So, we actually can have clinical failure from not picking the right drug for the bugs that are causing the most common infection. So clinical failure is a really big consequence of actually poor antimicrobial prescribing. Of course, one thing we go on about is adverse reactions of antibiotics and for the patient that's really important and I think personally, unless I'm asking that in every consultation, patients underplay and under-report it to us as practitioners. Diarrhoea, antibiotic-associated diarrhoea, is a significant adverse reaction that people under-report. We have about a three to four times increased risk of causing antibiotic-associated diarrhoea with broadening our spectrum from amoxicillin to amoxicillin/clavulanic acid. Thrush is a really significant adverse reaction that's quite disabling for people and you know seven to eight times risk of getting thrush with antibiotics. One thing we do worry as hospital practitioners which we see all the time is Clostridium difficile-associated diarrhoea. And the interesting thing about the adverse reaction of this type of diarrhoea, which requires antibiotics itself, is as you increase dose, as you increase the combination number and as you increase the days of therapy this risk gets higher from about two times to ten times if you've had one antibiotic course to five antibiotic courses within 60 days. So that sort of upscaling of antibiotics and increased duration does increase your risk. Allergies of course are something we always worry about but the thing that we start to need to conceive within our therapeutic considerations is that of antimicrobial resistance and certainly if we can narrow our antibiotics or reduce our antibiotic duration then we have a possibility of reducing anti-microbial resistance in Australian society.

So those consequences really are multifactorial. It's not just one thing that we're worried about.

That’s right.

And your article mentions some great do's and don'ts for best practice antimicrobial prescribing in general practice. Can you run through them for us briefly?

Yeah, so microbiological testing is one thing that can be a bit hard to decide about when you perform it and when you don't but certainly it's not indicated in every infection. Generally a standard urinary tract infections in the absence of a concern about difficult-to-treat organisms or previous antibiotics in recent times are not necessarily indicated. We'd always recommend using some type of guideline and so generally in Australia we really are very lucky to have the Therapeutic Guidelines or local available guidelines in many circumstances and would suggest people attempt to use them where possible. And one thing that helps people to work out where to improve is actually by documenting the reason that we're prescribing, not only for the practitioner who's prescribing but also patients see different general practitioners and so it's nice to understand why we're prescribing antibiotics should they re-present, and the duration is really important. The focus of the article is actually looking at the evidence of the shortest duration of antibiotic and so making sure we're prescribing to the shorter end of the recommended durations, as opposed to extending antibiotic durations, can really help the patient and society in terms of prescribing antimicrobial. And the other thing is that we generally wouldn't advocate for routinely providing a repeat prescription.

Okay some great tips there and there are times when anti-microbials are not needed. Why is this the case? What are some examples and where do prescribers go to get some more information and guidance on this?

So, in primary care it's really a balance about trying to work out which patient will benefit the most. And as we've talked about the multifactorial considerations are really complex I think. But in my head when I'm thinking about prescribing there are three main reasons I prescribe antibiotics when they're actually indicated, and we'll talk about when it's not indicated in that context. So, symptom resolution is the thing that patients really worry about most so when they come with the sore throat they want it gone and unfortunately for the patient antibiotics actually don't really help much. So, antibiotics shorten the duration of symptoms in a sore throat by about 16 hours which you know when you present that to a patient that's not actually that much time. So, we also prescribe for bacteriologic cure so when we're dealing with pregnant ladies with urinary tract infections or those undergoing a urological procedure, bacteriologic cure is actually more important. We like to eradicate meningococcal disease from someone's throat, you know that's really important. And the other thing and that we worry about is the reduction in complications. So, conditions where antibiotics are not necessarily required, in mild disease particularly, are things like the acute sore throat where viral causes are more likely in many situations. Acute rhinosinusitis in the mild situation there's not a lot of benefit, as you get more radiologic features or severity there is some benefit.

Okay, now your article does mention four great strategies to assist with optimal prescribing – the watch-and-wait method, to prescribe but may be not dispense yet, to specify durations that don't have to match the pack size, and changing default prescribing software to have a no repeat rather than defaulting to repeat. Do you mind just really briefly touching on these little four strategies?

So, the watch-and-wait and the prescribe-but-not-dispense could be sort of packaged together and it depends on your patient in front of you whether you think they'll be able to come back or what their preferences are as to what you might suggest for them. Watch-and-wait obviously is seeing how the patient goes and asking them to come back if things worsen because in that situation things may be more likely to be bacterial and require antibiotic therapy. Prescribe-and-not-dispense is where you give a patient a prescription but say really don't go out today and fill that at the pharmacy but wait a few days and see how you are going and that's really shown to have the similar patient satisfaction scores and actually decrease the antibiotic use quite considerably from about 90 to 30%. And specific durations, for example in uncomplicated cystitis, three days is only required but the pack size is seven so actually detailing the duration as opposed to just saying the standard pack size can actually reduce antibiotics in the community. And the no-repeat default can be changed in various IT systems and it can be a good strategy to stop that automatic entering repeats when you're prescribing for patients.

Okay great. In general Kathryn is there much evidence to support the efficacy of shorter courses of antimicrobials?

There is a lot and certainly this literature has evolved over, you know, the last 10 to 20 years. So if you just take things such as urinary tract infections, three days has been shown to be beneficial in many circumstances as opposed to seven. When we’re prescribing for pharyngitis, of course, most of it’s not required, short-course therapy has been shown to improve symptoms, five days compared to ten days but we still prescribe ten days because we're trying to decrease those complications in those higher risk patients and otitis media, short courses of less than seven days have similar outcomes to longer duration in therapy with children and even mild community-acquired pneumonia, actually three days in children has been found to be no different to five days. Therapeutic Guidelines currently recommend five, but our Australian and New Zealand Paediatric Infectious Diseases Group have actually recommended decreasing this to three days. And acute rhinosinusitis, something we were talking about before, the shorter course, three to seven days, has shown no difference to six to ten days of a sinusitis resolution or microbiological efficacy and relapse. So, lots of data there to support shorter course prescribing.

Okay fantastic. So there seems to be a recurring pattern of specific populations where a shorter course may not be appropriate. Can you tell us a bit more about these populations?

And this is the other thing I think about when prescribing is about patient risk. That as we can segregate people into high and lower risk based on various characteristics we can be more comfortable in prescribing and not prescribing and an example of this is a patient population with high risk of complications of group A strep in sore throat and that's the Aboriginal Torres Strait Islander group. So, we're prescribing really to prevent complications and I touched on that before in that the shorter course is actually for symptom resolution but the longer course we haven't shown that a shorter course reduces complications, so we still recommend a full 10-day course to prevent complications in a group A strep/pharyngitis. And urinary tract infections are a similar one in pregnancy. The shorter course has shown to reduce symptoms but actually microbiological eradication, so stopping growing the bug in the urine, is more beneficial at seven days. So, we have longer courses in pregnancy and those undergoing neurological procedures for urinary tract infections.

So, both health professionals and patients historically have been drilled about always completing their course of antimicrobial even if they feel better and some patients really do follow that diligently. But there are some exceptions to this rule. What are they?

When we're giving someone antibiotics and we're really not sure if it's bacterial or not bacterial it's often not bacterial and so we can safely stop antibiotics and people don't have any problems. But when we are sure we're treating a bacterial infection, then we still would suggest people complete the exact amount of days that the doctor recommends, and this is different to the pack size. So, you don't necessarily need to complete the whole pack but if we are treating a defined bacterial infection then we would recommend the days that is prescribed by the GP.

Wonderful well that's unfortunately all the time we've got for this episode, thanks for joining us today Kathryn.

No problem, thanks for having me.

[Music]

The views of the hosts and guests on the podcast are their own and may not represent Australian Prescriber or NPS MedicineWise. I'm Dhineli Perera and thanks for joining us on the Australian Prescriber Podcast.