Investigations for CAP in adults

The initial assessment of adults with community-acquired pneumonia (CAP) should include:

For adults with CAP and immune compromise, consider investigating for a broader range of pathogens; see Considerations in managing CAP in adults with immune compromise.

Table 1. Clinical and microbiological investigations for community-acquired pneumonia (CAP) in adults[NB1] [NB2] [NB3]Australasian College for Emergency Medicine (ACEM) and the Royal College of Pathologists of Australasia (RCPA), 2013, revised 2018
Low-severity CAP Moderate-severity CAP High-severity CAP
Low-severity CAP
oxygen saturation on room air
consider: chest X-ray; see Diagnostic imaging NAAT
Moderate-severity CAP
oxygen saturation on room air
chest X-ray; see Diagnostic imaging
blood culture
consider: NAAT sputum Gram stain and culture
High-severity CAP
oxygen saturation on room air
chest X-ray; see Diagnostic imaging
blood culture
NAAT
sputum Gram stain and culture
arterial blood gas analysis
consider: pneumococcal urinary antigen assay Legionella urinary antigen assay storing serum for serology
Note: NAAT = nucleic acid amplification testing NB1: This list of investigations is not comprehensive. The categorisations according to CAP severity in this table are based on the consensus of the Antibiotic Expert Group because evidence is conflicting. NB2: For adults with CAP and immune compromise, consider investigating for a broader range of pathogens; see Considerations in managing CAP in adults with immune compromise. NB3: For definitions of CAP severity, see Approach to severity assessment of CAP in adults.