Clinical features of CAP in adults

Adults with community-acquired pneumonia (CAP) often present with acute, nonspecific symptoms, such as cough (with or without purulent or coloured sputum) and fever (temperature more than 37.8°C). The presence of these symptoms does not indicate a need for antibiotic therapyMarchello, 2019; among patients presenting to primary care with respiratory tract symptoms, the incidence of pneumonia is low (0.4 to 5%Moore, 2017van Vugt, 2013). For advice on the initial assessment of cough in adults, including alarm symptoms and findings, see the Respiratory guidelines.

Acute bronchitis is a common differential diagnosis of pneumonia. Acute bronchitis is not associated with life-threatening complications (eg severe hypoxaemia) and usually resolves without antibiotic therapy; see Acute bronchitis.

Assess patients for the following signs and symptoms that indicate a greater likelihood of CAP¹Moore, 2017:

• temperature more than 37.8°C
• cough (with or without purulent or coloured sputum)
• dyspnoea
• tachypnoea (respiratory rate 18 breaths per minute or more at rest)
• oxygen saturation less than 95% on room air
• rigors
• pleuritic chest pain
• heart rate more than 100 beats per minute
• on chest examination:
  • dullness to percussion
  • poor air entry
  • bronchial breath sounds
  • crepitations (crackles) on auscultation that do not clear with coughing.

In some patients with CAP (eg older patients), nonrespiratory symptoms may be prominent (eg diarrhoea, headache, confusion).

To aid in diagnosing CAP in adults, perform a thorough history and examination to identify signs and symptoms (as above) and consider:

• assessment of severity
• clinical and microbiological investigations, including diagnostic imaging.

The clinical features of exacerbations of chronic obstructive pulmonary disease (COPD) and bronchiectasis can be similar to CAP; however, their management differs. For patients with COPD or bronchiectasis, consider a diagnosis of CAP if the patient is more unwell than with previous exacerbations, and consider a chest X-ray to exclude CAP if clinically indicated (see Diagnostic imaging for CAP in adults). For antibiotic management of adults with an exacerbation of COPD or bronchiectasis, see Antibiotic management of COPD exacerbations or Antibiotic management of bronchiectasis exacerbations.