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FilaMentor

16 Mar, 10 tweets, 5 min read

1/
First of 2 tweets! #GalactoMagic

45F w/ chronic lung disease and bronchiectasis presents to clinic w/ a chronic cough for the past 3 months.

She works as a construction worker in California. Exam is notable for poor dentition

2/
CT chest shows several nodules bilaterally in lung parenchyma with some cavitations

A bronch w/ BAL is performed & shows gram-positive bacilli, & a serum beta-d-glucan (BDG) is positive at 110 (positive > 80)

What is the likely cause of the BDG elevation?

1/8
Answer: Nocardia

All of these bacteria are gram + bacilli, but only nocardia causes BDG elevation

Other bacteria that cause +BDG include pseudomonas & mycobacteria

For a review of “false positives” & test characteristics of both BDG/GM, this figure is really helpful

2/
Nocardia can cause disease in both immunocompromised and immunocompetent hosts in the appropriate setting

In older studies, over 1/3 of patients were immunocompetent

pubmed.ncbi.nlm.nih.gov/8055469/

3/
Pulm nocardia is the most common presentation

The CNS is the most common extrapulm site

Some RF include:
⭐️depressed cellular immunity (lymphoma, HIV)
⭐️solid organ & stem cell transplant
⭐️steroids
⭐️alcoholism
⭐️diabetes
⭐️structural lung disease

pubmed.ncbi.nlm.nih.gov/22469352/

4/
Nocardia has been described to cause a positive serum BDG test due to its cell wall having polysaccharides that have beta glucan in it (see Tweet 1)

Hence, this would be considered a true positive

pubmed.ncbi.nlm.nih.gov/28407752/

pubmed.ncbi.nlm.nih.gov/32699055/

5/
The difficulty lies in the ability to say that BDG is from Nocardia, since both Aspergillus & Mycobacterial infections can have the same RF as Nocardia & present similarly (both can cause a + serum BDG)

@NEB_Skinner

6/
Nocardia can also be accompanied by these pathogens & lead to mixed infections, either at same site (Pulm Nocardia & Aspergillus) or different (CNS Nocardia & Pulm aspergillosis)

This is an uncommon occurrence

Here is a slide made by @NEB_Skinner

pubmed.ncbi.nlm.nih.gov/24378740/

7/
Another interesting point is that both Nocardia and PJP can cause elevated BDG, and both are treated with trimethoprim-sulfamethoxazole (Bactrim)!

8/
BDG can help in diagnosing invasive fungal infections (IFI) while considering host factors, clinical presentation, & prevalence of the fungal infection in your pt population

If +BDG doesn't fit w/ an IFI, ask these Qs to evaluate other causes of +BDG

pubmed.ncbi.nlm.nih.gov/33383818/

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More from @FilaMentor

FilaMentor

@FilaMentor

25 Mar

1/
First of 2 tweets! #GalactoMagic

80F nursing home resident presents w/ 3 days of fever, cough, & SOB

Vitals: T 38.6C, HR 110, BP 120/80, O2 94% on 3L. Exam notable for left basilar rhonchi & crackles

CXR shows LLL opacity. She is started on ceftriaxone & doxy

2/
2 days later, she is still having intermittent fevers with Tmax 38.1C, O2 94% on 3L, RR 30

A CT chest reveals a dense LLL consolidation

In addition to sputum cultures, which of the following tests should be ordered?

1/12
Answer: Blood cultures

The patient is a nursing home resident w/ ongoing fevers, hypoxia, high RR, with a LLL consolidation

In addition to sputum cx, the patient should also have blood cx (fits pneumonia severity index IV)

There is no dysuria to prompt an UA

Read 15 tweets

FilaMentor

@FilaMentor

23 Mar

1/
First of 2 tweets! #GalactoMagic

65F presents w/ 8 days of SOB. T 38C, HR 115, BP 100/60, RR 22, O2 92% on 100% non-rebreather & then intubated

Exam notable for crackles. CT chest shows GGO bilaterally

She has a +SARSCoV2 NAT resp swab; sputum & blood cultures are negative

2/
After remdesivir, dexamethasone, ceftriaxone & doxy, she defervesces. 3 weeks later, she has worsening SOB

Repeat CT chest shows worsening GGO & new pulm nodules

Which of the following is the most sensitive diagnostic modality for COVID-19 associated pulmonary aspergillosis?

1/11
Answer: BAL fluid culture

Although the most feasible test would be a tracheal aspirate culture, the highest yield test for Aspergillus is the BAL fluid culture

🌞Serum GM and BDG lack sensitivity compared to BAL testing

Read 14 tweets

FilaMentor

@FilaMentor

18 Mar

1/
First of 2 tweets! #GalactoMagic

50F w/ EtOH cirrhosis & DM presents to ED w/ AMS & decreased UOP. She is febrile & hypotensive

She is started on vasopressors & CVVHD via central lines in the ICU

Due to concern for SBP, she is started on ceftriaxone

2/
Initial blood & ascites cultures show no growth. She remains critically ill for 7 days and still having fevers

In addition to blood cultures, which of the following is the next best test to order?

1/13
Answer: Serum BDG

You have suspicion for invasive candidiasis given the RF of cirrhosis, critical illness in ICU w/ central lines, dialysis, & broad-spectrum antibiotics (see other RF in table)

Read 15 tweets

FilaMentor

@FilaMentor

11 Mar

A one tweet question! #GalactoMagic

60M w/ asthma from China presents w/ SOB secondary to an asthma exacerbation. He has never smoked cigarettes. A CT chest shows a 7mm right upper lobe nodule

Which of the following tests should be ordered for further evaluation of the nodule?

1/14
Answer: AFB sputum culture

Without knowing much about the patient, other than age, geographic risk, smoking status, & normal immune status, most common infectious cause of a solitary pulmonary nodule (SPN) is TB.

2/
It’s possible that the SPN may be latent TB, but we need to rule out active TB first (AFB sputum cultures x3) before considering latent TB

Fungal causes are less likely. If we want to work it up, it would be pathogen specific (e.g., Cocci Ab) & not broad antigen testing (BDG)

Read 15 tweets

FilaMentor

@FilaMentor

9 Mar

1/
First of 2 tweets! #GalactoMagic

75F w/ lupus, HTN, recent diagnosis of HIV (viral load 30,000, CD4- 57), presents to ED in winter w/ 4 weeks of shortness of breath & cough. T 38.5C, HR 105, BP 105/80, RR 20, O2 94% on 3L. Exam is notable for crackles & rhonchi in both lungs

2/
Labs: WBC 2,600, Hb 7.5 g/dL, platelet 70,000. CXR shows diffuse opacities. You have suspicion for Pneumocystis jirovecii pneumonia

Which of the following is the best non-invasive test to order to help confirm the diagnosis?

1/11
Answer: Serum BDG

⭐️LDH elevation is nonspecific and can be elevated in many diffuse pulm processes

Serum GM is not helpful in diagnosing PJP since its cell wall does not contain GM

BDG is a cell wall polysaccharide present in many pathogenic fungi including P. jirovecii

Read 13 tweets

FilaMentor

@FilaMentor

4 Mar

1/
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

2/
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?

1/14
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/

Read 17 tweets

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