Speaker:
00:00:05
Hi everyone.
Speaker:
00:00:06
Welcome to Febrile, a cultured podcast about all things infectious disease.
Speaker:
00:00:11
We use consult questions to dive into ID clinical reasoning, diagnostics
Speaker:
00:00:14
and antimicrobial management.
Speaker:
00:00:17
I'm Sara Dong, your host and a Med Peds ID doc.
Speaker:
00:00:20
Today's episode of Below the Belt is led by a team from Australia.
Speaker:
00:00:26
First up, we have Dr. Morgan Hui.
Speaker:
00:00:28
Morgan is a basic physician's trainee with an interest in infectious diseases.
Speaker:
00:00:33
He is currently working as an ID registrar at Peninsula
Speaker:
00:00:36
Health in Melbourne, Australia.
Speaker:
00:00:38
Hi, it's Morgan.
Speaker:
00:00:39
Very keen to be here today.
Speaker:
00:00:42
Dr. Jonathan Darby is an infectious diseases and general medicine physician.
Speaker:
00:00:46
He is the head of General Medicine at St. Vincent's Hospital, Melbourne,
Speaker:
00:00:50
and an Associate Professor at the University of Melbourne.
Speaker:
00:00:56
Hi.
Speaker:
00:00:56
It's great to be here with you today.
Speaker:
00:00:59
Dr. Max Olenski is an infectious diseases and general medicine physician with
Speaker:
00:01:03
an interest in tropical medicine and infections in immunocompromised hosts.
Speaker:
00:01:07
He is the current Perioperative Medicine Unit Clinical Lead at Peninsula
Speaker:
00:01:11
Health and a Sessional Academic with Monash University in Melbourne.
Speaker:
00:01:15
Hi, it's Max Olenski here.
Speaker:
00:01:17
Thanks so much for having us today.
Speaker:
00:01:18
Really excited for this podcast.
Speaker:
00:01:20
Dr. Catriona Halliday is the Principal Hospital Scientist in charge of
Speaker:
00:01:24
the Clinical Mycology Reference Lab at the University for Clinical
Speaker:
00:01:27
Pathology and Medical Research and New South Wales Health Pathology
Speaker:
00:01:31
based at Westmead Hospital in Sydney.
Speaker:
00:01:34
She is actively involved in teaching both scientific and medical staff in
Speaker:
00:01:38
medical mycology, and has a strong interest in culture independent tests to
Speaker:
00:01:42
aid in the rapid diagnosis of invasive fungal infections and antifungal
Speaker:
00:01:47
drug susceptibility surveillance.
Speaker:
00:01:49
Hi, it's Catriona Halliday, and nice to be here too.
Speaker:
00:01:52
Wonderful.
Speaker:
00:01:53
Thank you guys so much for coming.
Speaker:
00:01:55
We are just gonna quickly start by asking you to share a little piece
Speaker:
00:01:59
of culture, because we call Febrile everyone's favorite cultured podcast.
Speaker:
00:02:03
So really just sharing a little something non-medical that you like,
Speaker:
00:02:06
whether that's pop culture or hobbies, um, or other interests that you have.
Speaker:
00:02:11
So what have you guys been enjoying recently?
Speaker:
00:02:14
I had the pleasure of going to see recently for International Women's
Speaker:
00:02:18
Day, I went to see the RBG: Of Many, One, um, production about Ruth Bader
Speaker:
00:02:26
Ginsburg's life, which was fantastic.
Speaker:
00:02:28
It's one woman show, I think it's tour of the states, uh, and it's come back time
Speaker:
00:02:32
and time again in, in, uh, Australia.
Speaker:
00:02:34
That's cool.
Speaker:
00:02:35
I haven't seen that.
Speaker:
00:02:35
I was gonna say that in recent times, my daily routine has, uh,
Speaker:
00:02:39
incorporated the New York Times puzzles.
Speaker:
00:02:42
I, I sort of churn through them every morning while I'm
Speaker:
00:02:44
having my morning coffee.
Speaker:
00:02:45
And also I've been doing the cryptid crossword of late to try
Speaker:
00:02:48
and get my creative juices flowing.
Speaker:
00:02:50
Excellent.
Speaker:
00:02:51
Love a good puzzle.
Speaker:
00:02:52
Uh, Morgan.
Speaker:
00:02:54
Uh, since Covid, I think I've been picking up golf after lockdown.
Speaker:
00:02:58
Um, not that I play well, but it's enjoyable to get outdoors.
Speaker:
00:03:04
And then in the same vein, uh, I've been watching a lot of golf, YouTube,
Speaker:
00:03:08
especially being between studying.
Speaker:
00:03:09
It's very easy watching.
Speaker:
00:03:11
Um, and it's just something to turn my brain off at night, which is quite good.
Speaker:
00:03:16
Yeah, the turning your brain off is usually a, a common
Speaker:
00:03:20
theme on people's suggestions.
Speaker:
00:03:22
Um, and rounding us out, Jonathan.
Speaker:
00:03:24
Well, I saw you like travel and food.
Speaker:
00:03:26
So yesterday at weekend Australian time, I said to my kids, I'm gonna cook dinner,
Speaker:
00:03:31
and they requested bao buns, so I made bao buns yesterday, which was good fun.
Speaker:
00:03:36
Labor of love takes most of the day,
Speaker:
00:03:38
a lot of work.
Speaker:
00:03:39
was very nice.
Speaker:
00:03:40
Yeah, very nice.
Speaker:
00:03:42
Amazing.
Speaker:
00:03:43
I love it.
Speaker:
00:03:43
Well, thank you guys for sharing.
Speaker:
00:03:46
Um, all right, well, Morgan is in charge today and is gonna
Speaker:
00:03:49
take us through the case.
Speaker:
00:03:50
So I'll hand it over.
Speaker:
00:03:52
Thank you.
Speaker:
00:03:53
So today, our case involves a 49-year-old male who presents to the renal outpatient
Speaker:
00:03:58
department with a four month history of a slow growing, painless right elbow lesion.
Speaker:
00:04:03
He's adherent with his immunosuppression and a systems review is unrevealing.
Speaker:
00:04:08
His past medical history includes a renal transplant in 2017 for primary
Speaker:
00:04:13
focal segmental glomerular sclerosis.
Speaker:
00:04:16
His pre-transplant assessment did not reveal any infections for
Speaker:
00:04:20
which prophylaxis was afforded.
Speaker:
00:04:23
His early post-transplant course was complicated by pulmonary aspergillosis
Speaker:
00:04:28
and he was treated with a six month course of voriconazole with clinical,
Speaker:
00:04:32
biochemical, and radiological resolution.
Speaker:
00:04:36
At the time of seeing him, he has a stable allograft function, currently on low dose
Speaker:
00:04:40
prednisolone, everolimus, and tacrolimus, and his comorbidities include well
Speaker:
00:04:45
controlled hypertension, dyslipidemia, steroid induced osteoporosis, and GORD
Speaker:
00:04:50
(gastro-oesophageal reflux disease).
Speaker:
00:04:51
On examination his vitals were normal alongside a normal
Speaker:
00:04:54
cardio respiratory exam.
Speaker:
00:04:56
His abdominal examination revealed a non-tender right lower quadrant
Speaker:
00:05:01
mass underlying a hockey stick scar, consistent with a renal allograft.
Speaker:
00:05:05
He has a 1.5 centimeter non-tender mobile lump on the lateral aspect of his right
Speaker:
00:05:12
elbow, not tethered to the underlying skin without notable discoloration, overlying
Speaker:
00:05:18
skin changes, induration, nor sinus.
Speaker:
00:05:22
There were no other masses on examination of his lymph node stations.
Speaker:
00:05:27
At this point, is there anything else that you'd want to ask our
Speaker:
00:05:30
patients and what differentials do you think that you'd entertain?
Speaker:
00:05:35
Thanks Morgan.
Speaker:
00:05:35
So just to summarize, this is a middle aged gentleman who's a renal
Speaker:
00:05:39
allograft recipient with stable function on immunosuppression.
Speaker:
00:05:43
His post-transplant course was complicated in the early stages, uh,
Speaker:
00:05:46
with pulmonary aspergillosis, but he seems to have recovered from that with
Speaker:
00:05:50
therapy, uh, and presents now with an incidental painless lump on his elbow.
Speaker:
00:05:55
Some important questions that come to mind really are
Speaker:
00:05:57
clarification surrounding exposures.
Speaker:
00:05:59
Um, for instance, what he does for work, what sort of hobbies he has, um, has
Speaker:
00:06:04
he had any animal contact, or, a little bit more about his sexual history.
Speaker:
00:06:09
Uh, what else is important would be, um, whether there are
Speaker:
00:06:12
other locoregional infections or constitutional symptoms of note.
Speaker:
00:06:16
The differential diagnosis for a painless lump in a transplant recipient runs the
Speaker:
00:06:20
gamut from a foreign body reaction to things like a lipoma or other soft tissue
Speaker:
00:06:23
neoplasms, and this includes lymphoma.
Speaker:
00:06:26
But considering this is through the lens of an infectious disease
Speaker:
00:06:29
approach, I think it's important to entertain various sorts of infections.
Speaker:
00:06:32
And likewise, we'd entertain things like run of the mill bacterial
Speaker:
00:06:36
skin, soft tissue infections, like a furuncle or carbuncle.
Speaker:
00:06:39
But syphilis and cat scratch disease also appear amongst the differentials.
Speaker:
00:06:43
Considering a significant history, fungal etiologies need to be entertained,
Speaker:
00:06:46
and this includes disseminated aspergillosis alongside sporotrichosis,
Speaker:
00:06:50
and, um, more rare things like mucormycosis or rhizopus infection.
Speaker:
00:06:54
Um, and then the fine print would be things like mycobacterial infection, viral
Speaker:
00:06:58
or parasitic infections, things like TB or non tuberculous mycobacteria (NTM),
Speaker:
00:07:02
um, or cysticercosis or trichinellosis but those sort of things would really
Speaker:
00:07:05
come to, uh, the fore if his, um, exposure history was compatible.
Speaker:
00:07:09
So taking our case a bit further, his social history revealed that the patient
Speaker:
00:07:13
immigrated from the Philippines to Australia 18 years previously, where he
Speaker:
00:07:18
returns to visit family and friends every six to 12 months, but not in recent times.
Speaker:
00:07:23
He's in a long-term heterosexual, monogamous relationship and works in
Speaker:
00:07:27
maintenance at an aged care facility.
Speaker:
00:07:30
He's a sporadic gardener with no additional epidemiological
Speaker:
00:07:33
exposures, and does not report any recent animal nor insect contact,
Speaker:
00:07:38
nor recent locoregional infections.
Speaker:
00:07:41
He consumes no alcohol nor smokes tobacco.
Speaker:
00:07:45
On further history when pressed, he thinks that he might have had the onset following
Speaker:
00:07:49
a seamlessly innocuous traumatic injury against a doorknob without skin breach,
Speaker:
00:07:54
and no set associated systemic upset.
Speaker:
00:07:58
His routine lab results were unremarkable with white cell count,
Speaker:
00:08:02
LFTs, and inflammatory markers within normal limits, a stable renal function
Speaker:
00:08:06
compared to previous, a non-reactive RPR and a negative QuantiFERON
Speaker:
00:08:11
gold with a good mitogen response.
Speaker:
00:08:14
Ultrasound sonography of the lesion revealed two small circumscribed
Speaker:
00:08:18
ovoid masses suggestive of reactive lymphadenopathy.
Speaker:
00:08:23
This was clinically corroborated upon surgical review and was resected
Speaker:
00:08:28
en bloc with tissue set up for histopathological assessment alongside
Speaker:
00:08:32
routine mycobacterial and fungal cultures.
Speaker:
00:08:36
No organisms were seen from the Gram and Zeihl-Neelson stains, nor subsequently
Speaker:
00:08:40
cultured . However, filamentous fungi were noted on fluorescent staining.
Speaker:
00:08:46
Histopathological examination revealed multinucleated giant cells, and possible
Speaker:
00:08:52
copper penny, aka Medlar bodies.
Speaker:
00:08:55
In addition, there was a suggestion of a brown micro colony of hyphal elements
Speaker:
00:09:01
with suspicion for an underlying deep mycosis, and the specimen was sent for
Speaker:
00:09:06
further culture and identification.
Speaker:
00:09:09
I guess, now, what do you think is meant by deep mycoses and
Speaker:
00:09:13
how are they differentiated?
Speaker:
00:09:15
Yeah.
Speaker:
00:09:16
Thanks for that update, Morgan, on the case.
Speaker:
00:09:18
Um, to, to just take a step back.
Speaker:
00:09:20
This was a subcutaneous lesion and it, it didn't have any changes
Speaker:
00:09:26
on the skin, which would make us think of an inoculation injury.
Speaker:
00:09:29
But we were certainly taken by the history of his previous Aspergillus
Speaker:
00:09:34
infection in the lung and wondered if this was a site of disseminated infection.
Speaker:
00:09:40
And there is, as you've pointed out, Max, a broad differential in a immunosuppressed
Speaker:
00:09:45
transplant patient with any lesion.
Speaker:
00:09:48
But it was an unusual site.
Speaker:
00:09:49
It was an unusual appearance with relatively few other additional
Speaker:
00:09:54
symptoms, just that he brought this mass like lesion to our attention.
Speaker:
00:09:58
And so to be honest, I hadn't really used the term deep mycosis
Speaker:
00:10:03
in clinical practice before.
Speaker:
00:10:05
Um, I know it's, uh, been raised here and has been talked about in, in
Speaker:
00:10:08
some literature, but really when we think about these lesions, we have a
Speaker:
00:10:12
broad differential from, from fungal to atypical mycobacteria to other
Speaker:
00:10:16
organisms which may be indolent and slow growing in a transplant patient.
Speaker:
00:10:20
But this suggestion here with the, the pigmented nature of the fungal elements
Speaker:
00:10:25
certainly makes us concerned about a group of fungi, which we classify
Speaker:
00:10:30
in the dematiaceous mould group.
Speaker:
00:10:32
Um, this is an unusual finding, so this doesn't happen every day where
Speaker:
00:10:39
you find this on a biopsy and sometimes has been found in further other
Speaker:
00:10:43
organ sites such as brain or lung or subcutaneous skin and soft tissue.
Speaker:
00:10:50
So the, the overarching term we would sort of use for this would
Speaker:
00:10:54
be a phaeohyphomycosis, if it is related to a pigmented mold.
Speaker:
00:10:58
Actually had to look up the word "phaeo", 'cause I've always
Speaker:
00:11:00
wondered where that came from.
Speaker:
00:11:01
And, and that's, uh, Greek word for dusky.
Speaker:
00:11:04
So gray or, or black forming.
Speaker:
00:11:06
And this is thought to be the melanin in this group of fungal
Speaker:
00:11:10
infections' structure that causes that, that appearance.
Speaker:
00:11:15
So there's a few terms we use here.
Speaker:
00:11:17
And then the other term that we would consider is this term
Speaker:
00:11:21
of chromoblastomycosis, where a chronic infection, usually due
Speaker:
00:11:25
to inoculation but it could be dissemination in an appropriate host
Speaker:
00:11:29
such as this with dissemination.
Speaker:
00:11:31
Um, there is a well-known entity in the tropics where these patients have
Speaker:
00:11:36
a crusted verrucous like lesion on the skin with chromoblastomycosis.
Speaker:
00:11:41
And there's a range of specific species which are fairly geographically
Speaker:
00:11:45
distinct depending on where a patient may have spent time.
Speaker:
00:11:49
And so with this individual, whilst living in residential suburban
Speaker:
00:11:53
Australia, we did note that his history is from the Philippines and
Speaker:
00:11:57
traveling back and forth there fairly frequently with some sparse gardening.
Speaker:
00:12:02
So we were concerned about this family of organisms from that basic
Speaker:
00:12:07
microbiological description before we had a formal culture and identification
Speaker:
00:12:12
from our mycology reference laboratory.
Speaker:
00:12:14
The next step in his workup was the sterile tissue was sent to
Speaker:
00:12:18
a diagnostic mycology laboratory for specialized fungal cultures.
Speaker:
00:12:23
Uh, from here, Catriona will take us through exactly what happens
Speaker:
00:12:27
in the lab to get our diagnosis.
Speaker:
00:12:30
Thanks very much Morgan, and thank you Jon for that nice history and
Speaker:
00:12:34
my, I've now learned what phaeo means in the phaeohyphomyosis.
Speaker:
00:12:38
I've got a case at the moment, so that's good.
Speaker:
00:12:40
Um, okay.
Speaker:
00:12:41
So when the sample was sent to us for culture, we already knew that there were
Speaker:
00:12:47
fungal elements seen histologically
Speaker:
00:12:50
. When we receive samples in the fungal lab, it's really important that any
Speaker:
00:12:54
tissue samples aren't actually ground up.
Speaker:
00:12:57
We, we just make them into small pieces and put them onto the various agar and,
Speaker:
00:13:02
um, we don't grind them up because if this fungus was likely to be, or we
Speaker:
00:13:09
sometimes we don't even know if it will be, a mucormycete, this particular group
Speaker:
00:13:13
of fungi are really, really fragile.
Speaker:
00:13:15
Um, and grinding would destroy the hyphae and, and so the
Speaker:
00:13:18
organism would be non-viable.
Speaker:
00:13:21
So as a rule, no tissue samples are ground up in a mycology laboratory.
Speaker:
00:13:27
So these, sterile pieces of tissue were put onto a variety of different media.
Speaker:
00:13:31
We usually use a couple of different media, a very general purpose media
Speaker:
00:13:36
with no antibiotics such as Sabouroud dextrose agar, and then we use more
Speaker:
00:13:41
nutritious media such as a Sabouraud dextrose agar base, which might
Speaker:
00:13:46
have something like brain, heart infusion and some antibiotics like
Speaker:
00:13:50
chloramphenicol and gentamicin in them to suppress any bacterial growth.
Speaker:
00:13:56
So following inoculation, we then use plates, but some labs do use slopes.
Speaker:
00:14:02
The plates, we seal them with parafilm, and then we put them in an
Speaker:
00:14:05
incubator at 30 degrees, rather than 35 degrees, which is what would be
Speaker:
00:14:10
used for most of the bacterial growth.
Speaker:
00:14:13
And 30 degrees, I think most fungi are environmental organisms and
Speaker:
00:14:17
they just do better for growing at a slightly lower temperature.
Speaker:
00:14:21
We keep these plates for four weeks and look at them every couple of days.
Speaker:
00:14:26
And so the reason they're para filmed is, is both to, to keep the
Speaker:
00:14:30
lids closed, but also prevents dehydration when they're put in the
Speaker:
00:14:35
incubators for, for quite a long time.
Speaker:
00:14:38
So that's the reason we use that lower temperature.
Speaker:
00:14:40
And, in this particular case, after about 10 days, we noticed a small amount
Speaker:
00:14:45
of growth of a, of a dark gray fungus growing directly out of that tissue.
Speaker:
00:14:51
So as soon as we get positive culture, we would then always work
Speaker:
00:14:55
in a biological safety cabinet.
Speaker:
00:14:57
We would then put that organism and subculture it onto a general purpose
Speaker:
00:15:02
Saboroud agar with no antibiotics in it.
Speaker:
00:15:05
And we'll also prepare a slide culture by inoculating a potato dextrose agar plate.
Speaker:
00:15:12
In order to identify fungi in the conventional way, you, you really
Speaker:
00:15:18
need to see how those fungi are growing in their natural state.
Speaker:
00:15:22
And so for that, you, you can use macroscopic appearance, but
Speaker:
00:15:26
the macroscopic appearance can change depending on the media
Speaker:
00:15:29
that you might be using, how much light there might be exposed, you
Speaker:
00:15:33
know, to, and things like that.
Speaker:
00:15:34
The macroscopic appearance can be a bit of a guide, but that microscopic appearance
Speaker:
00:15:39
is what we need to identify something to the genus and ideally the species level.
Speaker:
00:15:46
So you need to use a media such as potato dextrose agar
Speaker:
00:15:49
to encourage that sporulation.
Speaker:
00:15:52
Other media that could be used for microscopy to prepare slide cultures
Speaker:
00:15:56
is cornmeal agar, which is probably a little bit less nutritious and
Speaker:
00:16:00
more encouraging of sporulation.
Speaker:
00:16:03
So in this particular case, again, we grew a very gray,
Speaker:
00:16:10
velvety fungus with radial grooves.
Speaker:
00:16:13
It changed and became a bit darker with age on the Sabourouds plate.
Speaker:
00:16:18
And there was a bit of a dark, exudate or, droplets forming
Speaker:
00:16:22
directly outta that colony.
Speaker:
00:16:25
The reverse of the colony was also dark, so the fact that it was dark
Speaker:
00:16:29
on the reverse as well as on the surface suggests that the organism
Speaker:
00:16:33
does contain melanin, which fits with what we've seen histologically.
Speaker:
00:16:38
Unfortunately the microscopic appearance of this fungus from the
Speaker:
00:16:42
slide culture was not very helpful.
Speaker:
00:16:44
We just got hyphae.
Speaker:
00:16:45
We didn't see any conidia forming, and so if you don't see conidia
Speaker:
00:16:49
forming out of that hyphae, we can't identify it using conventional methods.
Speaker:
00:16:55
Fortunately, we have the ability to overcome this problem and
Speaker:
00:16:59
perform DNA sequencing, which is, is actually now considered the gold
Speaker:
00:17:04
standard for identification of fungi.
Speaker:
00:17:07
There's a couple of different barcoding genes for fungal identification that
Speaker:
00:17:13
we rely upon, the internal transcribed space region, as well as some organisms
Speaker:
00:17:20
might identify better with something like the elongation factor gene.
Speaker:
00:17:25
But for this particular case, we used DNA sequencing of the internal
Speaker:
00:17:30
transcribed spacer region as well as the D1/D2 region of the 28S ribosomal DNA.
Speaker:
00:17:38
We did two different PCRs.
Speaker:
00:17:39
We sent that pCR product off the sequencing and ran the sequence
Speaker:
00:17:44
results against gen bank data databases using a, a BLASTn algorithm.
Speaker:
00:17:50
And I'd never had encountered the answer that we got.
Speaker:
00:17:55
But the answer we did get from both the ITS sequencing was 99.4%
Speaker:
00:18:02
identity to an organism called Falciformispora lignatalis.
Speaker:
00:18:07
And I might have butchered that pronunciation, but I'm happy
Speaker:
00:18:11
for someone else to correct it.
Speaker:
00:18:13
Um, and then the next closest match was another species within that
Speaker:
00:18:18
Falciformispora, uh, species, but it was further away at only 96% identity.
Speaker:
00:18:24
So we were pretty confident that the organism we'd come
Speaker:
00:18:26
across was this F.lignatalis.
Speaker:
00:18:32
We did try and do antifungal susceptibility testing for this patient,
Speaker:
00:18:36
but again, with antifungal susceptibility testing, you must have sporulation
Speaker:
00:18:41
and, uh, we didn't manage to induce sporulation and therefore we weren't
Speaker:
00:18:46
able to perform antifungal susceptibility testing in this particular case.
Speaker:
00:18:50
Was it far enough away to call it catrionelis or not quite?
Speaker:
00:18:57
It makes me feel better that you also doubt your pronunciation
Speaker:
00:19:02
like,
Speaker:
00:19:02
never come across this organism before and I'm yet, but I, and I haven't
Speaker:
00:19:06
even come across that genus before.
Speaker:
00:19:08
So,
Speaker:
00:19:08
Thank you.
Speaker:
00:19:09
Thank you so much.
Speaker:
00:19:10
Uh, I guess what do we make of this and the significance of this organism?
Speaker:
00:19:15
Would we call it a deep mycosis?
Speaker:
00:19:17
Yeah.
Speaker:
00:19:17
And is it how this syndrome typically manifests itself?
Speaker:
00:19:22
Um, well, as we've said already, uh, this is an unusual organism
Speaker:
00:19:25
and I think it's been implied as well that the world of mycology is
Speaker:
00:19:29
forever changing and it is difficult to keep up with this kaleidoscopic
Speaker:
00:19:33
landscape of fungal nomenclature.
Speaker:
00:19:35
But this syndrome is indeed, um, consistent with what we call mycetoma.
Speaker:
00:19:40
And whilst I am no budding mycologist, uh, I have done my research and we'll
Speaker:
00:19:45
talk a little bit about mycetoma now.
Speaker:
00:19:47
It is a chronic granulomatous subcutaneous infection caused
Speaker:
00:19:50
by several species of fungi as well as soil inhabiting bacteria.
Speaker:
00:19:54
Which is endemic within this so-called mycetoma belt, um, which spans
Speaker:
00:19:58
from 15 degrees south to 30 degrees north of the equator and really
Speaker:
00:20:02
within the tropics of the world.
Speaker:
00:20:03
Sporadic cases have been reported worldwide, including in temperate regions,
Speaker:
00:20:06
and it's really quite rare in Australia.
Speaker:
00:20:08
And when it does occur, it occurs in the northern states and territories,
Speaker:
00:20:11
which approach the tropics.
Speaker:
00:20:14
We make a distinction between actinomycetoma and eumycetoma,
Speaker:
00:20:18
the former being caused by soil inhabiting bacteria, and the latter
Speaker:
00:20:21
from fungis, such as in this instance.
Speaker:
00:20:23
And the typical presentation is usually with the triad of tumour, uh, sinus
Speaker:
00:20:27
tracts, uh, and macroscopic grains, which are essentially colonies or
Speaker:
00:20:31
aggregates of the infectious organism.
Speaker:
00:20:34
Uh, it can extend to adjacent structures including bone, muscle, lymphatics.
Speaker:
00:20:38
And the classic description from a long, long time ago was that of
Speaker:
00:20:41
Madura foot, named after a region in India called Madura, where people
Speaker:
00:20:45
would've stepped on this, these fungal organism, and it was quite disfiguring.
Speaker:
00:20:49
Risk factors as you might gather are typically environmental or related to
Speaker:
00:20:53
occupation, and thus it had previously been known or sometimes is known as
Speaker:
00:20:57
an implantation mycosis, uh, and risk factors also included, such as in this
Speaker:
00:21:01
instance, states of immunocompromised, whether they be inherited or acquired.
Speaker:
00:21:06
The main age for this sort of syndrome is in the thirties and typically occurs
Speaker:
00:21:10
in males with changing epidemiology based on an itinerant population
Speaker:
00:21:14
in other regions around the world.
Speaker:
00:21:16
It usually involves the, the feet, as an implantation mycosis where workers
Speaker:
00:21:20
might be not wearing shoes and exposed to thorns and other things
Speaker:
00:21:24
within the soil, and less likely to occur in parts of the torso, the
Speaker:
00:21:27
arms and other parts of the body.
Speaker:
00:21:29
Common organisms for mycetoma itself, or eumycetoma I should say.
Speaker:
00:21:33
Madurella mycetomatis, which is the, the classic one, but it's worthwhile
Speaker:
00:21:37
noting that eumycetoma itself is the minority of cases of mycetoma.
Speaker:
00:21:40
It's 35% of cases of mycetoma across the board and within eumycetoma,
Speaker:
00:21:45
Madurella mycetomatis, uh, accounts for 75% of eumycetoma.
Speaker:
00:21:50
Followed by Falciforma species such as the other ones that Katrina had
Speaker:
00:21:54
identified as being similar to the Falciforma lignatalis which
Speaker:
00:21:58
was identified in this case.
Speaker:
00:22:00
And they tend to differ by local epidemiology including
Speaker:
00:22:02
climate, vegetation, rainfall, and, and different soil types.
Speaker:
00:22:05
Little is known about the incubation period between inoculation and clinical
Speaker:
00:22:09
manifestations, given that many patients do don't recall a specific predisposing
Speaker:
00:22:12
injury, such as in this instance.
Speaker:
00:22:14
It's worth noting that there are atypical presentations that typically affect
Speaker:
00:22:17
immunocompromised hosts, whereby the classic triad might not be present.
Speaker:
00:22:21
There are numerous case reports, uh, out there that highlight a link with
Speaker:
00:22:25
the tropics in transplant recipients or those who are immunocompromised.
Speaker:
00:22:29
For instance, patients who have migrated from their country of origin to a place
Speaker:
00:22:33
that is not within the Mycetoma belt, and some 40 years later receiving a
Speaker:
00:22:37
transplant and then having this fungus identified from various parts of the body.
Speaker:
00:22:41
But there's yeah, um, really quite interesting cases out there.
Speaker:
00:22:44
So beyond clinical suspicion, if someone came in with a similar presentation, how
Speaker:
00:22:49
would you go about diagnosing mycetoma?
Speaker:
00:22:53
Uh, it's hard not to have a talk like this without saying that clinical impression
Speaker:
00:22:57
and an index of suspicion are paramount.
Speaker:
00:22:59
Uh, and they are.
Speaker:
00:23:00
Um, so the presence of that triad are certainly things that would give
Speaker:
00:23:03
you an indication, but beyond that, in terms of clinching the diagnosis,
Speaker:
00:23:07
it's a composite of growing the organism, and pursuing culture.
Speaker:
00:23:12
Whether that be with a fine needle aspirate of the growth, wherever
Speaker:
00:23:15
it may be on the body, uh, with subsequent inoculation under plates.
Speaker:
00:23:19
I might ask you at this instance, Catriona, I know you mentioned that you
Speaker:
00:23:22
would tend to culture these only at 30 degrees, but from my reading, sometimes
Speaker:
00:23:25
these get inoculated at both 30 degrees and uh, 37 degrees for a number of
Speaker:
00:23:29
weeks because different organisms within this eumycetoma syndrome tend to grow
Speaker:
00:23:34
predominantly different, uh, temperatures.
Speaker:
00:23:35
Is that fair to say?
Speaker:
00:23:36
Or something you don't always do?
Speaker:
00:23:38
Yeah, it is a fair enough question.
Speaker:
00:23:40
I guess we're guided by standards for recommending what
Speaker:
00:23:47
conditions we do grow fungi at.
Speaker:
00:23:49
And certainly the guideline we used is the CLSI guideline, which the people in
Speaker:
00:23:55
the states would be very well aware of and, and they make the suggestion that
Speaker:
00:23:58
whilst you can put things at two different temperatures and some, some labs do put
Speaker:
00:24:02
things at two different temperatures.
Speaker:
00:24:05
Every time you put more and more plates out, you dilute how much
Speaker:
00:24:09
sample you actually have to be able to try and, and grow things.
Speaker:
00:24:12
So for fungal work, the general recommendation is you
Speaker:
00:24:16
can just use 30 degrees.
Speaker:
00:24:18
Uh, but, you've gotta remember, there's also plates that get set up
Speaker:
00:24:21
for bacterial cultures, and there's no reason why many of these fungi
Speaker:
00:24:24
wouldn't actually grow on some of the bacterial plates as well, and that is
Speaker:
00:24:30
incubated at the higher temperature.
Speaker:
00:24:31
So we have in my own lab times when we, we get something growing, but it's also
Speaker:
00:24:36
growing on the bacterial plates as well.
Speaker:
00:24:39
Great, thanks for that.
Speaker:
00:24:40
So, beyond culture, the other things that are in establishing a diagnosis include
Speaker:
00:24:44
histopathology with evidence of chronic granulomatous reaction, and possibly
Speaker:
00:24:48
the presence of a grain, which given how rare it is, ought to be discussed directly
Speaker:
00:24:53
with histopathology at your own lab.
Speaker:
00:24:55
Um, given that this has not seen a great deal, and indeed when we returned
Speaker:
00:24:58
to the histopathologist and asked them was that bunch of fungi you saw in a
Speaker:
00:25:03
conglomerate consistent with a grain, and when they look through textbook,
Speaker:
00:25:05
they confirm that indeed was the case.
Speaker:
00:25:07
So, uh, good have good relationships with the various
Speaker:
00:25:10
disciplines around the hospital.
Speaker:
00:25:12
And imaging is used sometimes to determine extent of disease, whether
Speaker:
00:25:16
it's invading in surrounding tissues, uh, but also to suggest whether
Speaker:
00:25:20
or not, there may be improvements to help guide duration of therapy.
Speaker:
00:25:23
I might ask Catriona, just lastly, is there anything in particular,
Speaker:
00:25:27
you would say about sensitivities?
Speaker:
00:25:28
Um, I know we weren't unable to achieve sporulation in this instance,
Speaker:
00:25:31
but given this is , this was a rare fungus and something you hadn't quite
Speaker:
00:25:35
encountered before, clinically, um, or at a lab level, if you were even
Speaker:
00:25:39
able to achieve sporulation, would there be much to be gleaned from
Speaker:
00:25:43
undertaking sensitivity testing?
Speaker:
00:25:45
Yeah, so definitely.
Speaker:
00:25:47
We would, uh, try and do susceptibility testing on any fungus that grew from a,
Speaker:
00:25:52
um, and was deemed to be significant.
Speaker:
00:25:55
In this particular case, we, because we couldn't get s sporulation, we
Speaker:
00:25:59
couldn't do susceptibility testing.
Speaker:
00:26:01
If we had been able to do susceptibility testing, all we would be able to give
Speaker:
00:26:05
would be a value of, of what the, in minimal inhibitory concentration
Speaker:
00:26:09
was for that particular isolate.
Speaker:
00:26:12
Um, but that can often give clinicians some confidence that whatever drug
Speaker:
00:26:16
they've decided to treat with, you know, is likely to be effective or not.
Speaker:
00:26:21
There's certainly no break points available for any of these unusual fungi.
Speaker:
00:26:25
We, we really only have break points available for one organism and one
Speaker:
00:26:31
drug for Aspergillus fumigatus with voriconazole, but, and we don't really
Speaker:
00:26:36
have breakpoint for anything else, so we are really only gonna be able to
Speaker:
00:26:38
give you a number, which may give you confidence as to which drug can be used.
Speaker:
00:26:43
Uh.
Speaker:
00:26:44
From my experience with testing other dematiaceous fungi which grow
Speaker:
00:26:48
in, you know, from cases like this, quite often itraconazole is actually
Speaker:
00:26:52
really a, um, it suggests that it is quite an effective drug against
Speaker:
00:26:56
these dark, slow growing molds.
Speaker:
00:27:00
Uh, so.
Speaker:
00:27:01
I'm not a clinician, but that is kind of my experience in the lab side of things.
Speaker:
00:27:07
As you say, I think as clinicians we quite enjoy, uh, MICs that are low
Speaker:
00:27:11
numbers, but appreciate that these are just environmental cutoffs and
Speaker:
00:27:15
uh, it really comes down to trying to pick what you think is gonna
Speaker:
00:27:18
be the most, um, effective agent.
Speaker:
00:27:21
I think it'd be worth emphasizing that the biopsy is ideally an excisional
Speaker:
00:27:28
biopsy because it's unusual to get either histological diagnosis or an
Speaker:
00:27:33
effective culture on either an FNA.
Speaker:
00:27:36
Um, sometimes a core biopsy, but in this instance, we were fortunate enough to
Speaker:
00:27:40
have the surgical team perform a full excision, and I think that's really led
Speaker:
00:27:44
to a, an expedited diagnosis in this case.
Speaker:
00:27:47
I completely agree with that, Jon.
Speaker:
00:27:49
And it's the same as if we'd have to go down the path of using, if we
Speaker:
00:27:52
hadn't managed to grow it, if we'd gone down the path of having to
Speaker:
00:27:55
use PCR directly from the specimen.
Speaker:
00:27:58
Your, um, ability to get a, a positive meaningful result from a fine needle
Speaker:
00:28:03
aspirate is, is quite, quite a lot lower than it would be if you get
Speaker:
00:28:07
a nice, proper tissue specimen.
Speaker:
00:28:10
Jon, how did you go on to choose your antifungal therapy in this instance?
Speaker:
00:28:14
Yeah, so that was obviously a little bit complicated in the
Speaker:
00:28:18
sense that we didn't have the full susceptibility data to guide us.
Speaker:
00:28:23
And in these type of infections, there's no prospective randomized
Speaker:
00:28:28
clinical trials to determine the most effective drug therapy.
Speaker:
00:28:32
But we're used to dealing in these, let's call it gray zones, for the theme today.
Speaker:
00:28:38
Um, in ID where we have to treat based on what's being reported to work
Speaker:
00:28:44
and what we have familiarity with.
Speaker:
00:28:46
I think the surgical adjunctive therapy is really important in these cases.
Speaker:
00:28:51
If we can get local control with the surgical excision,
Speaker:
00:28:54
then that should be emphasized.
Speaker:
00:28:56
However, we still wanted to pursue some antimicrobial therapy in this case.
Speaker:
00:29:01
Just recalling the case that it is a transplant patient
Speaker:
00:29:04
on tacrolimus and everolimus.
Speaker:
00:29:07
There are a lot of drug, drug drug interactions to consider and reviewing,
Speaker:
00:29:12
you know, all of the literature in the past, a lot of the cases have been
Speaker:
00:29:15
treated perhaps in more resource limited settings with ketoconazole, which we would
Speaker:
00:29:19
rarely use in our setting currently.
Speaker:
00:29:22
Um, and then itraconazole has certainly been used as Catriona alluded to.
Speaker:
00:29:26
Many of the newer studies where there have been MICs reported, have reported
Speaker:
00:29:31
low values to the newer triazole, such as voriconazole or posaconazole.
Speaker:
00:29:36
We did have some experience with voriconazole in the past with this
Speaker:
00:29:39
patient, but perhaps given that that was not that long ago, in a time interval,
Speaker:
00:29:45
we considered a, a new agent perhaps being a better option to switch to.
Speaker:
00:29:50
So we decided to use posaconazole.
Speaker:
00:29:53
This certainly had some significant drug interactions and really reviewing this
Speaker:
00:29:58
carefully with our nephrology colleagues and looking at the drug interactions.
Speaker:
00:30:02
There's a significant interaction with the cytochrome P450 enzyme subset, 3A4.
Speaker:
00:30:08
And so we had to look at that and the posaconazole was expected to significantly
Speaker:
00:30:15
interact with tacrolimus so that the initial dose of the tacrolimus had
Speaker:
00:30:19
to be about a third of the baseline dosing, and the everolimus had to
Speaker:
00:30:23
be about 50% of the baseline dosing.
Speaker:
00:30:26
So the treatment was certainly initiated in close consultation
Speaker:
00:30:31
with the nephrology team.
Speaker:
00:30:33
We did that at a time when they were ready and able to do drug levels
Speaker:
00:30:37
quite frequently, and the tacrolimus actually had to come down further.
Speaker:
00:30:41
So this particular patient was on 0.5 milligrams bd, which eventually
Speaker:
00:30:49
went down to 0.05 milligrams BD in a step by sequential fashion,
Speaker:
00:30:54
as the levels stayed very high.
Speaker:
00:30:56
So whilst we look at reports of what is expected, it's a lesson that
Speaker:
00:31:01
you always have to individualize these drug drug interactions.
Speaker:
00:31:04
There was no ongoing imaging really for this particular site
Speaker:
00:31:08
'cause we could clinically feel it and palpate it very nicely.
Speaker:
00:31:11
I. Uh, we did review a cerebral image just for the completeness, uh, because
Speaker:
00:31:18
some of these organisms have been known to disseminate to the central
Speaker:
00:31:20
nervous system and that was normal.
Speaker:
00:31:22
Uh, and we did repeat his pulmonary scan, which had the stable pulmonary
Speaker:
00:31:26
nodules from his previous pulmonary aspergillosis with no change.
Speaker:
00:31:30
So we elected to treat for six months.
Speaker:
00:31:32
Uh, this was in the time where we had another worldwide epidemic going on
Speaker:
00:31:37
with, with Covid, and so it was quite challenging in terms of monitoring
Speaker:
00:31:40
and clinic visits, but we were able to get the patient in and ensure
Speaker:
00:31:45
that he remained symptom free after successfully completing the treatment.
Speaker:
00:31:53
Thanks to Morgan, John Max and Catriona for joining Febrile today.
Speaker:
00:31:58
Don't forget to check out the website febrilepodcast.com, where
Speaker:
00:32:01
you can find the Consult Notes, which are written supplements to the
Speaker:
00:32:04
episodes with links to references, our library of ID infographics,
Speaker:
00:32:08
and a link to our merch store.
Speaker:
00:32:10
Febrile is produced with support from the Infectious Diseases Society of America.
Speaker:
00:32:15
Please reach out if you have any suggestions for future shows or
Speaker:
00:32:18
wanna be more involved with Febrile.
Speaker:
00:32:19
Thanks for listening.
Speaker:
00:32:21
Stay safe and I'll see you next time.