Bacterial Pneumonia Differential Diagnoses

Updated: Sep 30, 2020
  • Author: Justina Gamache, MD; Chief Editor: Guy W Soo Hoo, MD, MPH  more...
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Diagnostic Considerations

Remember that the most prevalent causative organism in bacterial pneumonia is pneumococcus regardless of the host. Empiric therapy must be selected with this organism in mind.

Because the episode of aspiration is usually not witnessed, the diagnosis is inferred when a patient at risk of aspiration develops evidence of a radiographic infiltrate in characteristic anatomic pulmonary locations or bronchopulmonary segments.

Always consider the possibility of Legionella infection, because delayed treatment significantly increases mortality.

Despite the frequency of pneumonia and the large body of research and literature surrounding it, controversy remains regarding certain aspects of the evaluation and management of pneumonia. Much emphasis has been placed on the utility of diagnostic testing versus the role of empiric treatment. The following three aspects of disease are important in the management of pneumonia, in which diagnostic testing can play a pivotal role:

  • Determining the presence of pneumonia

  • Assessing disease severity at the time of presentation

  • Identifying the causative agent

Distinguishing pneumonia from other pulmonary pathologies, such as acute COPD or asthma exacerbation, can often present a significant challenge, particularly in patients with these underlying lung diseases. C-reactive protein (CRP) and procalcitonin values may help in distinguishing infectious pneumonia from noninfectious underlying disease exacerbations. [52]

Differentiation between CAP, healthcare-associated pneumonia (HCAP), hospital-acquired pneumonia (HAP), and other pulmonary pathology at presentation is important for several reasons, but primarily because the varying pathogens implicated in each category dictate the empiric therapy likely to be most useful. [3]

In children, the following conditions should also be taken into consideration:

Differential Diagnoses