Urgent Investigations in Suspected Community Acquired Pneumonia
| Test | Comment |
|---|---|
| Chest X-ray | See Table 62.3. |
| Full blood count | Leucocytosis or leucopenia are markers of sepsis and severe infection. |
| Electrolytes, urea and creatinine | To assess renal function and disease severity (urea >7.0). |
| C-reactive protein | As biomarker of treatment response. |
| Liver function tests | The identification of underlying or associated hepatic disease. |
| Arterial blood gases (ABG) | If oxygen saturations <92% on air, or in patients with COPD to assess for type 2 respiratory failure. |
| Urine for Legionella antigen | In those with severe CAP or during an outbreak. |
| Blood culture | Identification of pathogens and antibiotic sensitivity patterns allows selection of optimal antibiotic regimens. Blood for culture must be taken prior to starting antibiotics. |
| ‘Atypical’ serology | For patients with severe CAP or unresponsive to beta lactam antibiotics. ‘Atypical’ pathogens that cause pneumonia are Mycoplasma pneumoniae, Chlamydia pneumoniae, Chlamydia psittaci and Coxiella burnetii. |
| Sputum culture | For patients with CAP who are able to expectorate sputum. Sputum samples should be sent for Gram stain, culture and sensitivity tests. |
| HIV test | HIV testing should be offered to all adult patients with community-acquired pneumonia. |