Thread by @FilaMentor

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First of 2 tweets! #GalactoMagic

65F w/ history of heart transplant on tacrolimus, prednisone, & mycophenolate, presents w/ SOB and fatigue. Vitals are normal. Exam is notable for tender red bumps on the shins bilaterally. Labs are notable for absolute eosinophil count of 800

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CT chest shows scattered pulmonary nodules throughout. The team decides to order a serum beta-d-glucan (BDG)

Which of the following potential causes of her skin and pulmonary nodules is most likely to result in a positive serum BDG?

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Answer: Cocci!

Although no epi history was provided here, you can use several clues to get to the answer: eosinophilia, erythema nodosum, and +BDG

Although Crypto and Blasto can rarely cause +BDG, Cocci is much more likely to have a positive BDG

pubmed.ncbi.nlm.nih.gov/29125373/

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In this tweetorial, we will review the test characteristics of BDG for Cocci, and briefly touch on how to use the antibody tests to diagnose Cocci

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.@GRThompsonMD looked at performance characteristics of BDG for Cocci

Using a cut off of 80, they found a sens 44%/spec 91%

BDG can be useful for Cocci when epi factors suggest the disease, but other specific testing is not readily available

pubmed.ncbi.nlm.nih.gov/22692738/

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Using BDG for Cocci may depend on its life cycle. Cocci spherules (in hosts) have 60% BDG by dry weight, whereas arthroconidia (in environment) contain 20% BDG

pubmed.ncbi.nlm.nih.gov/15731053/

pubmed.ncbi.nlm.nih.gov/32000283/

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Before diving into which Cocci antibody tests to send, we need to be able to recognize coccidioidomycosis. As with all fungal infections, Cocci diagnosis relies on host, clinical, radiographic, and laboratory features

pubmed.ncbi.nlm.nih.gov/24575994/

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The most common things you will find in the exposure history is travel to or residing in an endemic area (like the Southwest US), and being in areas where there is a lot of dust in the air (sandstorms, construction sites, etc.)

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With clinical findings, patients can present as:
🎾community acquired PNA
🥎systemic symptoms with fever, fatigue, rash, arthralgias, erythema nodosum
⚾️eosinophilia (25-30% of cases have this finding!)

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Radiographic changes include
🐶acute findings (infiltrates, cavities, effusions, adenopathy, military infiltrates)
🐱chronic findings (nodules, thin-walled cavities)
➡️These nodules do not calcify! (unlike in Histo)

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The presence of Cocci Ab depend upon the host to mount an Ab response & exposure time

The response may be dampened in the immunocompromised

Repeat testing may not help in the immunosuppressed, but it may help if you are unclear about exposure time

pubmed.ncbi.nlm.nih.gov/28797486/

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For non-Cocci, IgM becomes + early, then converts to durable IgG response w/ lifelong immunity. But this doesn’t occur w/ Cocci

After the infection, many will lose IgM & IgG. Even though IgG is not detectable, there is durable immunity, as reinfection w/ Cocci is unlikely

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There are 3 main Ab tests for Cocci:

🌕enzyme immunoassay (EIA)
🌗immunodiffusion (ID)
🌓complement fixation (CF)

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First, we send the EIA: a qualitative test for Cocci IgM & IgG

+IgG test is confirmed by immunodiffusion-complement fixation (IDCF) (some labs do IDCF first)

If EIA or IDCF is +, then CF test is done to provide a titer (>1:16 suggests dissemination)

pubmed.ncbi.nlm.nih.gov/28797486/

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Negative EIA doesn't require confirmation, but serial testing may be needed because testing may have occurred prior to seroconversion (as we said before)

There’s controversy about isolated EIA IgM being a false + or a marker of early disease that needs confirmation

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To review, we need to send the serologies in the context of a compatible clinical presentation. The figure here can help you interpret the positive and negative EIA IgM and IgG and when to send confirmatory tests!

pubmed.ncbi.nlm.nih.gov/28797486/

For some more fun, here is another tweeotorial about Cocci

Enjoy!