, 14 tweets, 6 min read
Today I'm going to do a #Tweetorial on non-resolving pneumonia (NRP)! These are a series of pearls on a prior #MorningReport case that I gave earlier this year. We are going to cover definitions, differential diagnosis/schema & workup of NRP #IDTwitter #PulmTwitter
So first off, what is non-resolving pneumonia (NRP)?

It is a bit vague, but it's a lack of resolution of symptoms or radiographic findings over an expected time period despite appropriate antibiotic treatment.
Let's separate this term from "recurrent PNA", which consists of multiple episodes with symptom free intervals & radiologic clearance (e.g. aspiration PNA).

We will avoid the topic of "what is a pneumonia anyway?"
Well, what is an expected time course of improvement then?
Roughly, subjective improvement within 3-5 days.
Other findings can take much longer (Fig).
But these time frames are altered greatly by co-morbidities, age, severity, and infectious agent!

For my schema/DDx on non-resolving pneumonia, I will build around a schema by @foamid on reasons for antibiotic failure:
- Wrong Bug
- Wrong Drug
- Wrong Diagnosis (not a bug!)
- Wrong Host
- Lack of source control

1) Wrong Bug
- The etiologic agent may not be amenable to CAP (or even HAP) antibiotic coverage!
- Drug resistant organisms (e.g., MRSA, Pseudo, ESBL)
- Fungi (histo, blasto, crypto, cocci, aspergillus)
- Mycobacterium (TB & NTBM)
- Nocardia & Actinomyces!
2) Wrong Drug
- Not covering atypical organisms (e.g. treated with amox as outpatient)
- Not covering anaerobic organisms (e.g. empyemas/abscess)
- Wrong drug dosing (ask your pharmacist!)
- Poor drug penetration (don't use dapto for PNA!)
3) Wrong Diagnosis
- Up to 20% of "CAP" is non-infectious in etiology. Much of "CAP" is not CAP, especially if it isn't acting like CAP!
- Think inflammatory, vascular, neoplastic, iatrogenic/drug-induced (h/t to @UpToDate for help with DDx)

Non-Infectious Causes of NRP:

- Vasculitis: GPA, diffuse alveolar hemorrhage
- ILD: COP, eosinophilic PNA, AIP, PAP, sarcoidosis

- PE

- Lung cancer: can be infiltrate or post-obstructive PNA
- Lymphoma (can cause an alveolar infiltrate!)
- Amiodarone
- Nitrofurantoin
- Bleomycin
- Methotrexate
- Checkpoint Inhibitors (PD-1, PD-L1, etc)
- Heroin or Crack Use
- Radiation Pneumonitis

4) Wrong Host
- Underlying immunodeficiency (e.g. HIV/AIDS with PJP, organ transplant, malignancy, undiagnosed primary immunodeficiency)
- Co-morbidities and age can cause PNA to take longer to resolve
5) Lack of source control
- Ensure there is not an empyema or lung abscess present!
- Are the lungs seeded with an infection from elsewhere? (e.g. endocarditis)
- Does aspiration play a role? (recurrent PNA more than NRP)
So what is the workup if given a case of NRP?
- Review history/risk factors
- Get better imaging: CT chest, consider high-res for workup of ILD
- Ensure proper cultures, serologic tests
- Next, consider bronchoscopy to identify infectious pathogens
- Lung biopsy as last option
Thanks to all of those who read this post! I hope to post pearls from morning reports that I do throughout the year, which I hope you learn from (I certainly do!).

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