Common organisms in community-acquired pneumonia

Outpatient care
Streptococcus pneumoniae
Mycoplasma pneumoniae
Haemophilus influenzae
Chlamydophila pneumoniae
Respiratory virus (influenza A and B, adenovirus, respiratory syncytial virus, parainfluenza)
Inpatient (non-intensive care)
S pneumoniae
M pneumoniae
C pneumoniae
H influenzae
Legionella species
Aspiration-related oral flora
Respiratory viruses
Inpatient (intensive care)
S pneumoniae
Staphylococcus aureus
Legionella species
Gram-negative bacilli
H influenzae
  • From Mandell LA, Wunderink RG, Anzueto A, et al; Infectious Diseases Society of America; American Thoracic Society. Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults. Clin Infect Dis 2007; 44(suppl 2):S27–S72, by permission of Oxford University Press.