Aetiology of CAP in residents of an aged-care facility

Community-acquired pneumonia (CAP) mortality is higher in aged-care facility residents than in the general communityLiapikou, 2014. This is largely due to comorbidities and advanced age rather than infection with resistant pathogensFaverio, 2014 Kang, 2017.

Note: Streptococcus pneumoniae is the most common pathogen in aged-care facility residents with CAP.

The spectrum of pathogens identified in aged-care facility residents with CAP does not vary greatly from the general community. Streptococcus pneumoniae is the most common pathogenKang, 2017 Liapikou, 2014. For a summary of pathogens that cause CAP in adults, see Aetiology of community-acquired pneumonia (CAP) in adults.

Atypical pathogens¹ (eg Mycoplasma pneumoniae, Chlamydophila [Chlamydia] pneumoniae, Legionella species) are uncommon. Therefore, empirical antibiotic therapy to treat these pathogens is not routinely required, but may be considered if these pathogens (especially Legionella species) are suspected based on epidemiology, clinical history or risk exposuresFukuyama, 2013 Kang, 2017 Ma, 2013.

Although residents of aged-care facilities are at higher risk of being colonised with multidrug-resistant gram-negative bacteria, such as extended-spectrum beta-lactamase (ESBL)-producing bacteria, these organisms rarely cause CAP – see Risk factors for infection with a multidrug-resistant gram-negative bacterium Teramoto, 2015.

Only collect sputum samples for Gram stain and culture if the resident can produce sputum. Ideally, collect sputum samples before or soon after starting antibiotic therapy; interpret the results with care². The identification of enteric gram-negative bacilli (eg Klebsiella pneumoniae) in sputum usually reflects colonisation or prior antibiotic use, especially in residents with low- or moderate-severity CAP.

Empirical antibiotic therapy for CAP in residents of an aged-care facility is largely the same as for treatment of CAP in the general community. For additional considerations in the management CAP in residents of an aged-care facility, see Approach to managing community-acquired pneumonia (CAP) in residents of an aged-care facility.

¹ There is no universally accepted definition of atypical pathogens. The term is used to describe bacteria that are intrinsically resistant to beta lactams and not identifiable by standard blood or sputum culturesGarin, 2022.Return

² Gram stain of poor-quality sputum samples can give misleading results. Use a good-quality sample (presence of polymorphs but few or no squamous epithelial cells on microscopy), collected before starting antibiotics, to adjust antibiotic therapy – the pathogen should be predominant in the Gram stain as well as the culture.Return