Community-acquired pneumonia (CAP) typically presents with symptoms and signs consistent with a lower respiratory tract infection (i.e., cough, dyspnoea, pleuritic chest pain, mucopurulent sputum, myalgia, fever) and no other explanation for the illness. Older people present more frequently with confusion or worsening of pre-existing conditions, and without chest signs or fever.
Confirm diagnosis in all patients presenting to hospital with evidence of consolidation (new shadowing that is not due to any other cause) on chest x-ray. A chest x-ray should not be requested routinely for patients managed in the community.
Use the CURB-65 mortality risk score (hospital setting) or CRB-65 severity score (community setting), together with your clinical judgement, to decide whether to manage the patient in hospital or at home and to determine appropriate therapy.
Initial treatment is with empirical antibiotics, following national/international guidelines and local epidemiology. In hospital, administer antibiotics within 4 hours of presentation.
Send sputum and blood samples for culture in people with moderate- or high-severity CAP, ideally before antibiotics are started, and consider legionella and pneumococcal urine antigen testing.
Give supplemental oxygen to patients with oxygen saturation <94% (or <88% in patients at risk of CO2 retention).
Consider sepsis whenever an acutely unwell person presents with likely infection, even if their temperature is normal. Follow your local protocol for prompt management of all patients with suspected sepsis, or those at risk.
Community-acquired pneumonia (CAP) is defined as pneumonia acquired outside hospital or healthcare facilities. Clinical diagnosis is based on a group of signs and symptoms related to lower respiratory tract infection with presence of fever >38ºC (>100ºF), cough, mucopurulent sputum, pleuritic chest pain, dyspnoea, and new focal chest signs on examination such as crackles or bronchial breathing. Older patients present more frequently with confusion or worsening of pre-existing conditions, and without chest signs or fever.
This topic focuses on the diagnosis and management of non-COVID-19 CAP in adults. For patients with suspected or confirmed COVID-19 pneumonia, see our topic Coronavirus disease 2019 (COVID-19) Opens in new window. Consider all patients with cough, fever, or other suggestive symptoms to have COVID-19 until proven otherwise. Pneumonia due to COVID-19 is not covered in this topic.
History and exam
- blood culture
- sputum culture (± Gram stain)
- urinary antigen testing for legionella and pneumococcus
- polymerase chain reaction (PCR) and/or serological tests
- CT scan of chest
- chest ultrasound
- thoracocentesis and pleural fluid culture
- computer tomographic pulmonary angiography (CTPA)
- serum procalcitonin
- point-of-care CRP
Jonathan Bennett, MD
Honorary Professor of Respiratory Sciences
University of Leicester
JB is deputy medical director RCP Invited service Reviews, and speaker at National Society (e.g., BTS), Primary Care respiratory Society, and Society Cardiothoracic Surgeons meetings.
JB declares that he has no competing interests.
BMJ Best Practice would like to gratefully acknowledge the previous team of expert contributors, whose work has been retained in parts of the content:
Catia Cilloniz MSc, PhD
Hospital Clinic of Barcelona
Antoni Torres MD, PhD
Professor of Medicine
Pulmonary Intensive Care Unit
Hospital Clinic of Barcelona
CC and AT are each authors of a number of references cited in this topic.
Wei Shen Lim
Consultant Respiratory Physician and Honorary Professor of Medicine
Nottingham University Hospitals NHS Trust
WSL was chairman of the British Thoracic Society community-acquired pneumonia guidelines committee and a member of the guideline development group for the National Institute for Health and Care Excellence pneumonia guidelines. His institution has received unrestricted investigator-initiated research funding from Pfizer for a multicentre study of pneumococcal pneumonia in which he was the chief investigator, and research funding from the National Institute for Health Research for studies in pneumonia in which he was the principal investigator. He is also an author of at least one reference cited in the topic.
Section Editor, BMJ Best Practice
HDC declares that she has no competing interests.
Lead Section Editor, BMJ Best Practice
RW declares that she has no competing interests.
Comorbidities Editor, BMJ Best Practice
JC declares that she has no competing interests.
Drug Editor, BMJ Best Practice
AM declares that he has no competing interests.
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