HOST FACTORS ASSOCIATED WITH SPECIFIC PATHOGENIC CAUSES OF PNEUMONIA
Underlying Condition Associated Microorganism
Active smoking/chronic obstructive
lung disease
Streptococcus pneumoniae, Haemophilus influenzae, Legionella pneumophila
Nursing home residents S. pneumoniae, gram-negative bacilli, H. influenzae, Staphylococcus aureus, Chlamydia
pneumoniae, anaerobes, tuberculosis
Alcoholism S. pneumoniae (including drug-resistant strains), gram-negative bacilli, anaerobes, tuberculosis
Gross aspiration/poor dentitionAnaerobes
Travel to southwestern United
States
Coccidioides immitis
Exposure to bats Histoplasma capsulatum
Exposure to birds Cryptococcus neoformans, Chlamydia psittaci, H. capsulatum
Exposure to rabbits Francisella tularensis
Exposure to farm animals Coxiella burnetii (Q fever)
Viral influenza Influenza, S. aureus, S. pneumoniae, H. influenzae
Bronchiectasis, cystic fibrosisPseudomonas aeruginosa, Pseudomonas cepacia, S. aureus, Aspergillus species,
Mycobacterium avium complex
Intravenous drug use S. aureus, anaerobes, tuberculosis, Pneumocystis jiroveci
Endobronchial obstruction Anaerobes
Recent antibiotic therapy Drug-resistant S. pneumoniae, P. aeruginosa
Adapted from American Thoracic Society: Guidelines for management of adults with community-acquired pneumonia: Diagnosis,
assessment of severity, initial antimicrobial therapy, and prevention. Am J Respir Crit Care Med 2001:163:1730–1754.