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.
We will avoid the topic of "what is a pneumonia anyway?"
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!
- 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!
- 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!)
- Vasculitis: GPA, diffuse alveolar hemorrhage
- ILD: COP, eosinophilic PNA, AIP, PAP, sarcoidosis
- Lung cancer: can be infiltrate or post-obstructive PNA
- Lymphoma (can cause an alveolar infiltrate!)
- Checkpoint Inhibitors (PD-1, PD-L1, etc)
- Heroin or Crack Use
- Radiation Pneumonitis
- 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
- 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)
Is there interest in these posts continuing?!