Mycoplasma pneumoniae

Last author update: 1 September 2011
Last staff update: 9 August 2020

Copyright: 2003-2023,, Inc.

PubMed search: mycoplasma pneumoniae [title] pneumonia pulmonary

Elliot Weisenberg, M.D.
Page views in 2022: 939
Page views in 2023 to date: 837
Cite this page: Weisenberg E. Mycoplasma pneumoniae. website. Accessed October 4th, 2023.
Definition / general
  • Strict aerobe that lacks a true cell wall, 0.2 - 0.8 μm and among the smallest free living bacterias
  • Formerly called atypical pneumonia (atypical due to moderate sputum production and consolidation and only minimal leukocytosis)
Clinical features
  • Common in children and young adults, but may occur in older age groups
  • Causes community acquired pneumonia (eMedicine), either interstitial (usually) or bronchopneumonia (rare)
  • Often asymptomatic
  • Superimposed bacterial infection may occur
  • Diagnosis: rarely biopsied, diagnose with complement fixation antigen assays; cold agglutinins present in 50% of cases
Gross description
  • Reddish blue, congested, patchy lungs; usually no pleuritis
Microscopic (histologic) description
  • Bronchiolitis, interstitial and minimal intra-alveolar involvement with widened alveolar septa due to lymphoplasmacytic inflammatory cells
  • Intra-alveolar proteinaceous material
  • Neutrophilic infiltrate in bronchioles acutely, bronchiolar metaplasia, lymphoplasmacytic infiltrate in bronchial wall and pneumocyte hyperplasia

Gliding phase
Differential diagnosis
Back to top
Image 01 Image 02