Summary
Definition
History and exam
Key diagnostic factors
- age <50 years
- persistent cough
- dry cough
- long duration of symptoms
Other diagnostic factors
- recent community exposure
- throat involvement
- fever
- headache
- diarrhea
- bullous myringitis
- lung rales/crepitations
- rash
Risk factors
- close community settings
- immunosuppression
- cigarette smoking
- chronic lung disease
- travel
- male sex
- immunomodulating drugs
Diagnostic investigations
1st investigations to order
- chest x-ray
- WBC count
- hemoglobin
- LFTs
- oxygen saturation in air
- BUN level
- real-time reverse transcription polymerase chain reaction (RT-PCR) for SARS-CoV-2
Investigations to consider
- urinary Legionella antigen
- sputum culture for Legionella
- molecular diagnosis of Mycoplasma pneumoniae or Chlamydophila pneumoniae
- serology for atypical pathogens
- nasopharyngeal viral cultures
Treatment algorithm
presumed atypical bacterial pneumonia: nonpregnant adult
presumed atypical bacterial pneumonia: pregnant or child
Contributors
Authors
Ran Nir-Paz, MD

Associate Professor in Medicine
Department of Clinical Microbiology and Infectious Diseases
Hadassah Hebrew University Medical Center
Jerusalem
Israel
Disclosures
RNP declares that they have no competing interests.
Peer reviewers
Mark Woodhead, BSc, DM, FRCP
Honorary Senior Lecturer (University of Manchester)
Consultant in General & Respiratory Medicine
Department of Respiratory Medicine
Manchester Royal Infirmary
Manchester
UK
Disclosures
MW is an author of a reference cited in this topic.
Ethan Rubinstein, MD
H.E. Sellers Research Chair in Infectious Diseases
Head
Section of Adult Infectious Diseases
Department of Internal Medicine
Department of Medical Microbiology
University of Manitoba
Winnipeg
Canada
Disclosures
At the time of the peer review, Professor Rubinstein declared no competing interests. We were made aware that Professor Rubinstein is now deceased.
Differentials
- Coronavirus disease 2019 (COVID-19)
- Typical bacterial pneumonia
- Viral pneumonia
More DifferentialsGuidelines
- Diagnosis and treatment of adults with community-acquired pneumonia
- The management of community-acquired pneumonia in infants and children older than 3 months of age
More GuidelinesPatient leaflets
Pneumonia
More Patient leafletsCalculators
Community-acquired pneumonia severity index (PSI) for adults
CURB-65 pneumonia severity score
More CalculatorsVideos
Tracheal intubation: animated demonstration
Bag-valve-mask ventilation: animated demonstration
More videosLog in or subscribe to access all of BMJ Best Practice
Use of this content is subject to our disclaimer