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Pneumonia Diagnostic Evaluation

CXR and baseline bloods should be taken in all patients.

Bloods tests should include:
  • FBC, EUC, LFTs (particularly for atypical pneumonia) and glucose.

  • VBG – degree of respiratory failure +/- lactataemia in sepsis.

  • Recent evidence suggests that blood cultures are particularly poor at influencing patient management in mild CAP and should be reserved for high risk groups, including those with severe sepsis. ALIEM have produced a good resource on blood cultures in pneumonia.

Pneumonia specific tests:

These should be considered in admitted patients and chosen in consultation based on clinical presentation and seriousness of illness

  • Sputum culture

  • Pneumococcal urinary antigen assay

    • Can be performed rapidly in most laboratories on routine urine specimens and is reasonably sensitive and specific (especially in bacteraemic adults)
  • Legionella urinary antigen for Legionella pneumophila

  • Nose and throat swabs for respiratory viruses (PCR)

    • Use the green viral swab rather than the blue bacterial culture swab
  • Mycoplasma, Legionella, Chlamydia and influenza serology

    • Frequently requested, but in practice very unlikely to help diagnosis acutely or change management. Acute serology needs to be analysed in the context of convalescent titres which are frequently never sent.

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