Last reviewed: 20 Sep 2021
Last updated: 11 Aug 2020



History and exam

Key diagnostic factors

  • presence of risk factors
  • age <50 years
  • persistent cough
  • dry cough
  • long duration of symptoms

Other diagnostic factors

  • recent community exposure
  • throat involvement
  • fever
  • headache
  • diarrhoea
  • 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
  • haemoglobin
  • LFTs
  • oxygen saturation in air
  • serum urea 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 Chlamdophila pneumoniae
  • serology for atypical pathogens
  • nasopharyngeal viral cultures

Treatment algorithm



Ran Nir-Paz, MD
Ran Nir-Paz

Associate Professor in Medicine

Department of Clinical Microbiology and Infectious Diseases

Hadassah Hebrew University Medical Center




RNP has received research grants from US-Israel Binational Science Foundation, Hebrew University, Rosetrees Trust, and SpeeDx. He is chair of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for Mycoplasma and Chlamydia Infections (ESGMAC). RNP is a consultant for and has stocks in eDAS Healthcare.

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.

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