[Music] Welcome to the Australian Prescriber Podcast. An
independent, no-nonsense podcast for busy health professionals.
Hi, and welcome to this second podcast in the Australian
Prescriber series on updates to Therapeutic Guidelines: Antibiotic. Part 1 was
aimed primarily at the hospital level, whereas this podcast focuses on
infections in the 99% of the world outside the hospital walls. I’m Dr Justin
Coleman, a GP who peddles drugs on a street corner in Brisbane, but always in
an evidence-informed way.
The Antibiotic Guideline was a first ever TG publication way back
when I was a med student. And yes, that was post-penicillin, and I reckon it’s
still the greatest. It’s the OG. Today we’re going to take a guided tour
through the human body. We will start at the kidney, head to the bowels, lungs,
skin, and pay a special visit at the end to the genitalia. With me is your tour
guide, Dr Kate McKenzie. And Kate is a fellow GP and she’s on the primary care
group behind the publication of this guideline. Kate, our tour is going to take
us to all the dark places where pathogens like to hide. That’s the thing about
bacteria. They get around, Kate.
They certainly do, Justin. I’m looking forward to going on this
tour with everybody.
Lovely. Well like an uninvited house guest, bacteria turn up to
the party, make a mess of the bathroom. But happily we hired security so we
never travel without some antibiotic backup. First stop, Kate McKenzie, the
bladder. You get UTI symptoms, you think they have a UTI and you treat and of
course you treat according to the antibiotic guidelines, which you can look up
as has always been the case. The big change is that trimethoprim is now the
third-line option for acute cystitis in nonpregnant adult females due to
increased resistance. I think it’s up to 20% resistance in many places. So
let’s talk Kate, for non-pregnant females under the age of 65, I think we’ve
got 2 approaches. One is to consider watchful waiting [nonantibiotic therapy] and
the next is for the antibiotics. Is that right?
Yeah, that’s right, Justin. So there was a bigger emphasis on this
update on the option of non-antibiotic treatment, which I think is becoming a
lot more popular with some patients. And in that group, so for those patients
who are under 65 years with mild cystitis symptoms, they can choose, with
you, to use the non-antibiotic management. And so by non-antibiotic management,
we’re really talking about giving pain relief, so an anti-inflammatory [drug] and
monitoring [of] their symptoms.
And the reasoning behind that is that many get better within a
week with or without antibiotics. I think the number needed to treat to make
one extra person symptom-free on day 3 is somewhere between 3 and 6. So on
average you’re certainly making the symptoms shorter, but you have to realise
it’s only one in 3 to one in 6 that it’s actually going to make a
change and improvement.
That’s right. So most will be better after 7 days with or without
antibiotics. And then I suppose the other thing that people can be concerned
about with that is the risk of progression to pyelonephritis, but that is
actually fairly low. So there’s a small risk of progression to pyelonephritis,
which is slightly reduced if you do give an antibiotic, but it’s probably less
than 5% that would progress to that.
Thank you. So Kate, if trimethoprim is now a third-line option,
what is preferred?
Yeah, so nitrofurantoin I think was in the old guideline, but
that’s been promoted to number one. So I think there’s been some concern about
using that [nitrofurantoin] in the past. But in short durations it’s actually a
very safe antibiotic, as long as your eGFR [estimated Glomerular Filtration
Rate] is over 30.
Okay. And we’re talking about nitrofurantoin for adults and older
children who are 29Â kgs or more.
And who can take tablets. So for lots of kids it’s not an option,
but for older kids it may be an option.
Another antibiotic I’ve never used has crept its way in called
fosfomycin, F-O-S-F-O-M, fosfomycin. Tell us about that.
That’s right. So I don’t think many of us have used it. So it’s an
antibiotic, you can use a one-off dose of it, and it’s highly effective in
treating UTIs. There’s very little resistance [among E. coli isolates] in
Australia. There’s obviously very little resistance because nobody uses it, but
even internationally where it has been used, there’s very little resistance to
it. So it sounds great. The downside of fosfomycin is it’s not on the PBS
[Pharmaceutical Benefits Scheme], so your patients would be out of pocket for
that, so that’s not going to be appropriate for everybody. But if your
patient’s willing to pay for a one-off dose of antibiotic, then it is an
option.
Okay, thank you. So nitrofurantoin is first line. Looking at
continuous antibiotic prophylaxis, I have a handful of patients who are taking
it long-term to prevent recurrent UTIs, as is often the case with antibiotics
over the years with increasing resistance. There’s a bit of a trend away from
that.
That’s right, it’s certainly de-emphasised in this guideline. So
we have recommended trying non-antibiotic prophylaxis first and they have
actually included a recommendation for methenamine hippurate in this guideline.
It’s one of those things that comes in and out depending on which study’s been
published most recently but, there’s enough evidence at the moment to put it in
there as an option. For some patients it might help.
And there’s also a recommendation that before you start continuous
prophylaxis you give a chance to a couple of other methods?
That’s right. So trying either patient-initiated treatment or
post-coital prophylaxis are recommended before continuous prophylaxis. And so
depending on the patient and on the frequency and cause of their UTIs, those
are both options to try prior to trying a continuous prophylaxis.
Wonderful. We probably don’t have time to go into much more
detail, but I noticed there’s also new content on UTI management in children
younger than 3 months, which of course is always both tricky and does require
some pretty serious follow-up in case there’s underlying abnormalities. I’ll
let listeners look that up themselves in the new version of Antibiotic
guidelines. We’ll move beyond the bladder, Kate, and take ourselves to the gut.
Looking at infectious diarrhoea, there’s been a lot of work done
on the section talking about faecal testing and a reminder to us all that, like
most tests, we only should test if the result is likely to make a difference.
And the guideline panellists have decided that it’s most likely to make a
difference in more severe or prolonged symptoms or bloody diarrhoea or where
the patient is immunocompromised, I guess with exceptions where there’s public
health implications in a nursing home or something like that. But in general,
we should be less enthusiastic about getting those faecal samples for routine
infectious diarrhoea.
That’s right. There’s a nice little table about when you should
consider testing, but I think you covered most of the times when that would be
appropriate. So very severe diarrhoea, bloody diarrhoea. Patients with
immunocompromise or prolonged diarrhoea that was going for more than 5 days, or
then there are a few patient groups with moderate diarrhoea, so people over [older
than] 70 [years], younger than 3 months or in the third trimester of pregnancy,
or people with very significant comorbidities you might consider testing those
as well. But that’s right, only if you think that you would give an antibiotic
if you get a specific result back is when you test.
And in terms of getting that result, GPs now have the choice
between faecal culture, the good old-fashioned way and some of their PCR
[Polymerase Chain Reaction] testing. PCR is certainly quite tempting. It’s a
quicker result and we tend to think it nails the result. But one of the issues
I think is that it does multiply a tiny amount of that bacteria in the stool,
meaning that we do tend to get more of those false positives and perhaps more
than one positive because you are really just measuring a small amount of
bacteria in the stool, which you get to some extent even on someone’s stool if
they don’t have diarrhoea.
Which is full of bacteria.
That’s the problem about poo.
That’s it. Yeah. So a positive PCR result has to be interpreted
with caution and if your patient is getting better regardless or if you don’t
think that’s the most likely cause of their symptoms, then you wouldn’t treat
based on that.
Any word on travellers’ diarrhoea? I notice perhaps the days of
travelling South East Asia with your little box of antibiotics ready to pop at
the first sign of diarrhoea perhaps isn’t quite so effective or useful as we
thought.
Yes, that’s right. So there’s only a few people where it may be
appropriate. People [with moderate or severe travellers’ diarrhoea] who are at
very high risk of having complications if they were to get travellers’
diarrhoea and who are travelling to an area where there’s not going to be [adequate]
access to healthcare. The problem, I suppose, with sending people off with
those antibiotics is one, that they don’t necessarily self-diagnose and treat
appropriately or at the right time, and, there’s evidence that it doesn’t
reduce the visits to local healthcare facilities for diarrhoea.
Well, speaking of travelling, it’s time we travelled to yet
another area of the body. Let’s go to the lungs. With bronchiectasis, there’s
been an update in both adults and children with bronchiectasis. Children, of
course, you really should have paediatric involvement because we really need to
look at caring for their lungs in the long term, but with adults. Talk to me
about the content on directed therapy versus empirical therapy for
bronchiectasis.
Yeah, so this was interesting. So there’s actually pretty good
evidence that if you can direct the therapy in bronchiectasis, you’ll get a
better outcome. So what the recommendation is, is that obviously you take a
sputum culture or a swab at the time of diagnosis before you start an
antibiotic, but also if you have a result from the last 12 months, suggesting
the colonising agents, then you can direct your therapy to those colonising
agents. And there are recommendations for different agents in the Antibiotic
guideline. So for Haemophilus [influenzae], Moraxella [catarrhalis],
Streptococcus pneumoniae, and Pseudomonas aeruginosa, you can
have a look and treat accordingly.
Thank you, Kate. Let’s journey outwards to the skin.
Diabetes-related foot ulcers. There’s a new thing talking about mild infection
and even detecting infection and certainly when they updated the Ulcer and
Wounds guideline, there was a strong emphasis on the fact that if you keep
swabbing these things, regardless of whether there’s a significant infection or
not, you often do grow something but that doesn’t help you treat. So the idea
is look for signs very indicative of infection before you take a swab.
Yeah, that’s right, Justin. So I suppose the first thing with your
considerations about treating a diabetic foot ulcer is first to decide if
there’s actually an infection of the ulcer. So if there are no signs of
infection and we all know what those are, so redness, inflammation, heat,
significant pain surrounding [the ulcer], purulent discharge, if none of those
signs exist, it’s probably not infected. So there’s no need to treat with
antibiotics. If those signs do exist, swabbing the ulcer is still not
particularly useful because what you grow could still be a colonising agent.
It’s not necessarily useful to direct your therapy. However, if you’ve got microscopy
from a tissue sample, so a biopsy, then that can be a useful way to direct your
therapy. Then if you find out that you do have an infected ulcer, looking at
the guideline, there’s some useful algorithms and tables about how you should
decide to treat, because as we probably all know, these ulcers are complicated.
Treating them is complicated and they often are worse than they might look at
first.
A reminder that if we are going to use oral therapy legitimately, in
patients with moderate infection of diabetes-related foot ulcers, we do tend
towards higher doses of whatever it is, amoxicillin + clavulanate, or
cephalexin in order to penetrate the area and be effective. So if you are going
to treat, do go for those higher doses. Just to mention a couple of other
updates, which we won’t go into too much, but there’s one on impetigo and one
on periorbital cellulitis. Tell us about those.
So the impetigo chapter’s been updated. There was a lot of
discussion about it. In GP land, we obviously see impetigo quite a lot, but
just a reminder to consider risk of rheumatic fever when you’re treating
impetigo and if there are risk factors for rheumatic fever, then you consider
treating even mild impetigo more aggressively. So treating it with an oral
antibiotic rather than topical. And I think they added in an option to use
trimethoprim + sulfamethoxazole as a second line agent in that one as well. But
still dicloxacillin, flucloxacillin, and cephalexin are your first
recommendations.
And the periorbital cellulitis, we won’t go into it in much
detail, but I noticed there are some big fancy tables.
So there was an ophthalmologist on the group and so it’s worth
listeners having a look at those tables because they’re quite useful just to
consider at times when periorbital cellulitis needs to be monitored more
carefully or treated more carefully because of risks for converting to orbital
cellulitis, which is an emergency that needs immediate hospital and
ophthalmological management.
We’ll finish now at the genitalia. There’s been some extra work
done on post-exposure prophylaxis. What’s that regarding?
So there’s a section here now mentioning the use of doxy [doxycycline]
for post-exposure prophylaxis. I don’t think there’s a specific drug
recommendation there, but more like a recommendation to consider it and to look
at the Australian sexual health management guideline [Australasian Society for
HIV, Viral Hepatitis and Sexual Health Medicine (ASHM) 2023 Consensus statement
on doxycycline prophylaxis (Doxy-PEP)] if that is something you want to
consider. And it would be in people who are at very high risk, especially of
syphilis, but also chlamydia and, to some extent, gonorrhoea, although we have
a lot of doxycycline resistance to gonorrhoea in Australia.
Thank you. And we might finish with syphilis. Always dear to my
heart. I’ve lived and worked in remote communities for 7 years of my life so
I’m no stranger to treating syphilis, but I guess most GPs in Australia are
relative strangers to it, although unfortunately becoming more familiar with it
again.
That’s right. Unfortunately, it’s been cropping up in more and
more unexpected areas over the last few years. So there are new recommendations
in the guideline, one about diagnosis and also about management of syphilis.
Well, Kate McKenzie, thank you for your input. It’s been a
pleasure having you talking about the new Therapeutic Guidelines: Antibiotics.
Thanks for coming along.
You are very welcome, Justin. And I would encourage people to have
a look at the guideline. There’s lots of really good information – so much work
that goes into more than just the drug recommendations. So if you’ve got some
time and you want to do some reading, there’s lots of interesting information
in the guideline that we haven’t covered today.
[Music]
My guests’ views are their own and don’t represent Australian Prescriber,
and my views are certainly all mine.