Atypical pneumonia (non-COVID-19)

Last reviewed: 2 Sep 2023
Last updated: 03 Nov 2021



History and exam

Key diagnostic factors

  • age <50 years
  • persistent cough
  • dry cough
  • long duration of symptoms
More key diagnostic factors

Other diagnostic factors

  • recent community exposure
  • throat involvement
  • fever
  • headache
  • diarrhea
  • bullous myringitis
  • lung rales/crepitations
  • rash
Other diagnostic factors

Risk factors

  • close community settings
  • immunosuppression
  • cigarette smoking
  • chronic lung disease
  • travel
  • male sex
  • immunomodulating drugs
More risk factors

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
More 1st investigations to order

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
More investigations to consider

Treatment algorithm


presumed atypical bacterial pneumonia: nonpregnant adult

presumed atypical bacterial pneumonia: pregnant or child



Ran Nir-Paz, MD
Ran Nir-Paz

Associate Professor in Medicine

Department of Clinical Microbiology and Infectious Diseases

Hadassah Hebrew University Medical Center




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




MW is an author of a reference cited in this topic.

Ethan Rubinstein, MD

H.E. Sellers Research Chair in Infectious Diseases


Section of Adult Infectious Diseases

Department of Internal Medicine

Department of Medical Microbiology

University of Manitoba




At the time of the peer review, Professor Rubinstein declared no competing interests. We were made aware that Professor Rubinstein is now deceased.

  • Differentials

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