132: Not Your Average Brodie

Sara Dong: 00:00:04

Hi everyone.

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Welcome to Febrile, a cultured podcast about all things infectious disease.

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We use consult questions to dive into ID clinical reasoning, diagnostics,

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and antimicrobial management.

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I'm Sara Dong, your host.

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I'll start by introducing our guests for this episode.

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First up is Dr. Veronica Santos.

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She completed medical school at the University of Puerto Rico and is currently

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a second year in pediatrics residency at University Texas or UT Health Houston.

Veronica Santos: 00:00:32

Hi, I am Veronica Santos.

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We have a returning guest, Dr. Misti Ellsworth.

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She's an Associate Professor of Pediatric Infectious Diseases at McGovern

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Medical School and UT Health Houston.

Misti Ellsworth: 00:00:43

Hi, Misti Ellsworth!

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And rounding out the team, we have Dr. Sebastian Shrager.

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He completed his pediatric residency at Broward Health in Fort Lauderdale,

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Florida before completing a fellowship in Infectious Diseases at the University of

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Texas Medical Center in Houston, Texas.

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He just started his job as an attending at Wolfson Children's

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Hospital in Jacksonville, Florida.

Sebastian Shrager: 00:01:04

Hi, I am Sebastian Shrager.

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As everyone's favorite cultured podcast, we like to kick

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off the show by asking our guests to talk about a little piece of culture.

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Really just something non-work, non-medical related

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that brings you happiness.

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So, Veronica, maybe I'll start with you.

Veronica Santos: 00:01:18

Sure.

Veronica Santos: 00:01:19

Um, I've been reading a book, We Are Liars, which is now a Hulu series.

Veronica Santos: 00:01:25

I've been really enjoying this book and plan on reading the pre sequel after this.

Sara Dong: 00:01:29

Very nice.

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Sebastian, how about you?

Sebastian Shrager: 00:01:34

Yeah, so, uh, I'm, I'm really excited for the World Cup.

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It's coming to the United States this summer, and I have, uh, tickets to

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Germany-Ecuador, and France-Norway.

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I'm super pumped.

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I'm a big soccer fan and I can't wait.

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It's so exciting.

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Yeah.

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It's gonna be, it's gonna be awesome.

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Um, and Misti, how about you?

Misti Ellsworth: 00:01:54

So I spend most of my free time attending and

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embarrassing my tweens and teenagers at sporting events and performances.

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When I'm not embarrassing my kids, I like to read and I'm also really

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enjoying the, uh, Shrinking series.

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All right, well, today's consult question I have heard is about

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ankle pain, so I will hand it over to Veronica to tell us about this patient.

Veronica Santos: 00:02:20

Yes.

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So to start with, we have a 14-year-old female.

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She came in with chronic, intermittent right ankle pain for the past three

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years, and she presented with acute worsening over the last 10 days.

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Her right ankle pain was intensified during soccer practice.

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Three days later, pain worsened and she was now unable to

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bear weight on her right foot.

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She had two separate visits to urgent care where x-rays were normal and her

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pain was attributed to tendonitis.

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On day nine, after orthopedics evaluation, MRI of the right foot and labs were done.

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On initial exam, her vitals were notable for temperature of 98.2, heart rate of 84,

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blood pressure of 115/60, respiratory rate of 15 and saturating at 97% in room air.

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On focused physical exam, she had swelling diffusely about the right

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heel with tenderness to palpation and a positive squeeze test.

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There was no erythema, warmth, or induration noticed and sensation

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and active movements were intact.

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Her initial labs were significant for a marked increase in inflammatory

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markers with no leukocytosis.

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Her CRP was 115 and her ESR was 39.

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She had slight decrease of hemoglobin to 11.8 with normal platelet count.

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Further workup included right ankle MRI, which was remarkable for a

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3.8 cm proteinaceous cyst in the calcaneal tuberosity with adjacent

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patchy marrow edema and enhancement suggestive of a Brodie's abscess.

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The MRI was also notable for edema and enhancement of the quadratus plantae

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muscle with a intramuscular fluid collection suggestive of myositis

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with possible early polymyositis.

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Sebastian, based on this initial presentation, what is your

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differential diagnosis so far and would you treat empirically?

Sebastian Shrager: 00:04:14

Yeah, so great history.

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So Staph aureus is king here.

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That's the most common organism by far.

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You can also see Group A Strep and Strep pneumo, which still show up.

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She's a little too old for Kingella.

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Um, so that's lower in the differential and she's not immunocompromised or using

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IV drugs, so Pseudomonas is less likely.

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And then without sickle cell disease, Salmonella drops way down the list.

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That said, Brodie abscesses can be absolutely polymicrobial.

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Management wise, this is where people sometimes jump too fast for antibiotics.

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If the kid looks stable and not septic, I'd actually hold antibiotics

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and call our friends in orthopedics.

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Incision and drainage gives you the best chance of finding a bug and holding off

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on antibiotics will increase that yield.

Veronica Santos: 00:05:02

What if they say no to an I&D (incision & drainage)?

Sebastian Shrager: 00:05:05

Yeah.

Sebastian Shrager: 00:05:05

Um, well, I'll try to persuade them first, but if they still say no, then

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cefazolin alone is totally reasonable.

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It covers MSSA well and makes oral step down easy to cephalexin, or

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cefadroxil, which are great PO options.

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If you're living in a MRSA heavy area, then vancomycin makes sense.

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And then if you want to also cover gram-negatives and MRSA, you could

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do ceftriaxone and vancomycin.

Veronica Santos: 00:05:32

Those are all great differentials.

Veronica Santos: 00:05:34

Now how about I give you more history to see if we can add anything else?

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She was born term with no complications.

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Her only medical history is tendinitis of her right ankle for the past three years.

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She has no pertinent surgical history or family history.

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Her vaccines are up to date.

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She does have pertinent travel history that include a trip to Galveston

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Beach in Texas where she stabbed her right ankle on a piece of wood.

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The piece of wood was spontaneously expelled from the

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puncture site two weeks later.

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About five months prior to presentation, she also went swimming in Pensacola

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Beach, Florida, and about two and a half months prior, she went

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swimming on Canvasback Lake, Texas.

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She refers exposure to multiple animals, including ticks, fleas,

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mosquitoes, horses, cattle, chickens, possums, iguanas, and even field mice.

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And she also has two vaccinated dogs.

Veronica Santos: 00:06:28

How does your differential change now with this additional history, Sebastian?

Sebastian Shrager: 00:06:32

So be careful when you go to Galveston Beach, it looks like,

Sebastian Shrager: 00:06:35

'cause you can get poked with a stick.

Sebastian Shrager: 00:06:37

Um, now this case gets more interesting because of the water and wood exposure.

Sebastian Shrager: 00:06:41

Uh, you have to think about Mycobacteria marinum, which loves salt and brackish

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waters, and fits a slow indolent course.

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The Vibrio species as well, especially vulnificus and alginolyticus,

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even though we usually think of them as more aggressive.

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She also swam in lakes, so Aeromonas hydrophilia comes into play plus

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rapid growing mycobacteria, since they're literally everywhere,

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everywhere in all water and soil.

Sebastian Shrager: 00:07:07

The wood exposure opens the door to fungi like Sporothrix schenckii, probably

Sebastian Shrager: 00:07:12

lower on the list, but not zero, which really drives home the key point.

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Send the bone.

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Get aerobic, anaerobic, AFB and fungal cultures because with Brodie's abscesses,

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especially with environmental exposure, the diagnosis lives in the microbiology.

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I'd also keep a sample on the side to send the PCR testing, just

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in case the cultures don't grow.

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We really do have a broad differential.

Veronica Santos: 00:07:38

I think at this point we're all ready to get some answers.

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So our patient underwent two I&Ds by orthopedics.

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To our surprise, the pathology and cultures sent from the operating room

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revealed Vibrio vulnificus causing acute osteomyelitis, Brodies abscesses,

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myositis and bursitis of the right ankle.

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The patient was then transitioned from IV vancomycin and piperacillin-tazobactam

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to ceftriaxone and doxycycline.

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Sebastian, can you talk more on Brodie's abscess, because this

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is one of those diagnoses that feel rare and it actually is.

Sebastian Shrager: 00:08:10

Yeah, exactly.

Sebastian Shrager: 00:08:11

Yeah.

Sebastian Shrager: 00:08:12

So first off, pediatric osteomyelitis overall isn't that common?

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It's only about 2 - 20 cases per a hundred thousand kids, and Brodie abscess

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makes up only around 2% of those cases.

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So you're already dealing with something pretty unusual, and what makes it

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tricky is that it's, it's not your classic toxic looking osteomyelitis.

Sebastian Shrager: 00:08:34

A Brodie abscess is really a subacute form of hematogenous osteomyelitis.

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Instead of widespread infection, you get this localized intraosseous abscess,

Sebastian Shrager: 00:08:44

basically a smoldering infection that the immune system has partially contained.

Veronica Santos: 00:08:49

Which makes sense in kids, right?

Sebastian Shrager: 00:08:51

Yeah, totally.

Sebastian Shrager: 00:08:52

So most pediatric osteomyelitis comes from the bloodstream, right?

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And the growth plates have this unique vascular anatomy with

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slow flow, looping vessels.

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Bacteria get in.

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The immune system walls it off, and instead of clearing it, you

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end up with the Brodie's abscess.

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Location wise, Brodie's abscesses love long bones.

Sebastian Shrager: 00:09:15

Tibia is the big one, about half of the cases, and then the femur.

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And interestingly, uh, Brodie abscesses tend to involve the diaphysis more

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than the metaphysis, which is a little different from what we usually think

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about with acute osteomyelitis in kids.

Veronica Santos: 00:09:31

We were all surprised by Vibrio vulnificus

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being the causative agent.

Veronica Santos: 00:09:35

Dr. Ellsworth, can you share more on why this was such an unusual case?

Misti Ellsworth: 00:09:40

So what made this case really interesting to us is

Misti Ellsworth: 00:09:43

how completely un-Vibrio it was.

Misti Ellsworth: 00:09:46

So when we think about Vibrio vulnificus, we usually think about

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very dramatic, very fast infections.

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So someone cuts their leg in seawater and within days they're septic.

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They've got hemorrhagic bullae, necrotizing fasciitis.

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Sometimes they end up even in the ICU.

Misti Ellsworth: 00:10:01

Osteomyelitis just isn't what comes to mind when we think of this bug.

Misti Ellsworth: 00:10:06

And in fact, when you look at the literature, Vibrio

Misti Ellsworth: 00:10:08

osteomyelitis is incredibly rare.

Misti Ellsworth: 00:10:11

Most of what's out there are single case reports.

Misti Ellsworth: 00:10:13

There aren't any case series and there aren't guidelines talking about it,

Misti Ellsworth: 00:10:17

and Vibrio doesn't even show up on the usual list of osteomyelitis pathogens.

Misti Ellsworth: 00:10:22

One of the few detailed reports is from the Journal of Infectious

Misti Ellsworth: 00:10:25

Diseases in 1990, and that case really mirrors what we saw.

Misti Ellsworth: 00:10:29

In that report, the patient had a fairly typical exposure, brackish water and a

Misti Ellsworth: 00:10:34

skin injury, but instead of progressing rapidly, the infection kind of smoldered.

Misti Ellsworth: 00:10:39

He initially improved with the antibiotics, but over the course

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of weeks to months, he developed worsening pain and swelling and

Misti Ellsworth: 00:10:46

eventually imaging showed osteomyelitis.

Misti Ellsworth: 00:10:48

The total time course was about 13 weeks, which is just not how

Misti Ellsworth: 00:10:52

we're taught that Vibrio behaves.

Misti Ellsworth: 00:10:54

That's what made our patients so challenging.

Misti Ellsworth: 00:10:56

There was no explosive presentation, no early sepsis, no

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necrotizing soft tissue infection.

Misti Ellsworth: 00:11:02

It said it almost looked like an orthopedic or an inflammatory

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condition at first with this chronic pain, local tenderness, no skin

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findings, and that really delayed the diagnosis in this patient.

Misti Ellsworth: 00:11:15

What's striking is that Vibrio infections are usually the opposite of indolent.

Misti Ellsworth: 00:11:19

Large surveillance studies showed that they present as gastroenteritis,

Misti Ellsworth: 00:11:23

wound infections, or primary septicemia, not chronic bone disease.

Misti Ellsworth: 00:11:27

Even during outbreaks, osteomyelitis is almost unheard of, and one Israeli

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outbreak with over 60 invasive cases, only one patient developed

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osteomyelitis, and there's not a whole lot of details in that case.

Misti Ellsworth: 00:11:41

So the big takeaway for us was this.

Misti Ellsworth: 00:11:42

Marine exposure plus persistent focal symptoms should keep

Misti Ellsworth: 00:11:46

Vibrio on the differential, even if the timeline feels wrong.

Misti Ellsworth: 00:11:50

Partial treatment, early antibiotics, or lack of source control may

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blunt that classic fulminant course and allow a deep infection like

Misti Ellsworth: 00:11:57

osteomyelitis to slowly declare itself.

Misti Ellsworth: 00:12:01

And finally, this case is a good reminder that when symptoms don't resolve,

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especially pain, repeating imaging and getting deep cultures really matter.

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Because even organisms we think of fast and furious can occasionally surprise

Misti Ellsworth: 00:12:13

us by being slow, quiet, and sneaky.

Veronica Santos: 00:12:16

Thankfully despite the chronicity of this

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infection and it being Vibrio, our patient had really good outcomes.

Veronica Santos: 00:12:22

On day 15, the second OR culture was positive for Vibrio vulnificus.

Veronica Santos: 00:12:26

On day 16, her inflammatory markers were down trending, and the patient

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was doing better clinically.

Veronica Santos: 00:12:32

After completing three days of IV antibiotics, she was sent home with

Veronica Santos: 00:12:36

one month supply of doxycycline.

Veronica Santos: 00:12:39

Patient was followed up in clinic one month after.

Veronica Santos: 00:12:42

At this point, inflammatory markers continue to downtrend with ESR

Veronica Santos: 00:12:46

at 41 and CRP less than three.

Veronica Santos: 00:12:48

The patient completed 12 more days of doxycycline for a total of 42 days.

Veronica Santos: 00:12:53

On day of completion, her ESR level was at 19 and CRP

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continued to be less than three.

Veronica Santos: 00:12:59

The patient was later cleared by orthopedics to return to soccer play.

Veronica Santos: 00:13:03

The takeaway from all of this is to think that Brodie's abscess can be subacute,

Veronica Santos: 00:13:08

smoldering, a form of osteomylitis that often lacks systemic toxicity.

Veronica Santos: 00:13:13

When able, as Sebastian said, always send the bone, deep OR culture

Veronica Santos: 00:13:18

should include aerobic, anaerobic, AFB, and fungal cultures, especially

Veronica Santos: 00:13:23

with environmental exposures.

Veronica Santos: 00:13:25

Plus marine exposures and persistent focal pain should always keep

Veronica Santos: 00:13:29

Vibrio on the differential, even when the timeline feels wrong.

Misti Ellsworth: 00:13:34

Thanks so much to Veronica, Sebastian, and

Misti Ellsworth: 00:13:36

Misti for joining Febrile today.

Misti Ellsworth: 00:13:38

Don't forget to check out the website febrilepodcast.com, where

Misti Ellsworth: 00:13:42

you'll find the Consult Notes, which are our written show notes for the

Misti Ellsworth: 00:13:46

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Misti Ellsworth: 00:13:50

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Misti Ellsworth: 00:13:52

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Misti Ellsworth: 00:13:56

Please reach out if you have any suggestions for future shows or

Misti Ellsworth: 00:13:59

wanna be more involved with Febrile.

Misti Ellsworth: 00:14:01

Thanks for listening.

Misti Ellsworth: 00:14:02

Stay safe and I'll see you next time.